JP5032943B2 - 3D shape measuring apparatus and 3D shape measuring method - Google Patents

3D shape measuring apparatus and 3D shape measuring method Download PDF

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JP5032943B2
JP5032943B2 JP2007288849A JP2007288849A JP5032943B2 JP 5032943 B2 JP5032943 B2 JP 5032943B2 JP 2007288849 A JP2007288849 A JP 2007288849A JP 2007288849 A JP2007288849 A JP 2007288849A JP 5032943 B2 JP5032943 B2 JP 5032943B2
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秀和 荒木
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本発明は、被計測物の3次元形状を計測する3次元形状計測装置及び3次元形状計測方法に関する。   The present invention relates to a three-dimensional shape measuring apparatus and a three-dimensional shape measuring method for measuring a three-dimensional shape of an object to be measured.

従来、物体の3次元形状を計測する方法として位相シフト法が広く用いられている。位相シフト法は光切断法の一種であって、投影装置により被計測物に特定のパターンを投影し、被計測物の表面で乱反射された投影像を投影装置の投影光軸と異なる方向から撮像装置で撮像し、この撮像装置で撮像した濃淡画像(以下、単に「画像」と呼ぶ)を画像処理することで被計測物の3次元形状を計測するものである。以下、位相シフト法の原理について更に詳しく説明する。   Conventionally, the phase shift method has been widely used as a method for measuring the three-dimensional shape of an object. The phase shift method is a kind of light cutting method, in which a projection device projects a specific pattern onto the object to be measured, and the projection image irregularly reflected on the surface of the object to be measured is taken from a direction different from the projection optical axis of the projection device. The three-dimensional shape of the object to be measured is measured by image processing with an apparatus and image processing of a grayscale image (hereinafter simply referred to as “image”) captured by the imaging apparatus. Hereinafter, the principle of the phase shift method will be described in more detail.

先ず、投影装置から正弦波状に輝度が変化する縞パターンを被計測物に投影し、この縞パターンの位相を、例えばπ/2ずつずらして撮像装置で撮像するという手順を、縞パターンの位相が1周期分移動するまで複数回(最低3回、通常は4回以上)繰り返す。ここで、撮像装置で撮像された4枚の画像上の同じ位置での輝度(濃度)は、絶対的な明るさはその位置での被計測物の表面性状や色等により変化しても、相対的な輝度差は必ず投影パターンの位相差分だけの変化を示すから、その位置での投影されたパターンの相対位相値が求められる。   First, the projection device projects a fringe pattern whose luminance changes in a sine wave shape onto the object to be measured, and the phase of the fringe pattern is shifted by, for example, π / 2 and imaged by the imaging device. Repeat several times (minimum 3 times, usually 4 times or more) until moving for one cycle. Here, the luminance (density) at the same position on the four images captured by the imaging device is the absolute brightness, even if the absolute brightness changes depending on the surface property or color of the measurement object at that position, Since the relative luminance difference always shows a change of only the phase difference of the projected pattern, the relative phase value of the projected pattern at that position is obtained.

相対位相φは投影縞パターンの1周期毎の値、即ち−π〜πの間の値となるから、複数周期分投影された縞の絶対位相Φを求めるには、縞次数n(一端から他端に向かって数えてn周期目の縞であることを表す値)の縞が、撮像された各画像上でどの位置にあるかを推定する処理が必要である。   Since the relative phase φ is a value for each period of the projected fringe pattern, that is, a value between −π and π, in order to obtain the absolute phase φ of the fringes projected for a plurality of periods, the fringe order n (from one end to the other) It is necessary to perform processing for estimating where the fringes (values representing the fringes in the nth cycle counted toward the end) are located on each captured image.

そして、撮像された4枚の画像の各点において、相対位相値と縞次数とを用いて、上記絶対位相Φ(=φ+2nπ)を求める。この処理を以下では「位相接続処理」と呼ぶ。位相接続処理によって求められた絶対位相Φが等しい点を連結して得られる線(等位相線)が、光切断法における切断線と同じく被計測物をある平面で切断した断面の形状を表すから、この絶対位相Φをもとに三角測量の原理により被計測物の3次元形状(画像各点での高さ情報)が計測できる。   Then, the absolute phase Φ (= φ + 2nπ) is obtained using the relative phase value and the fringe order at each point of the four captured images. This process is hereinafter referred to as “phase connection process”. A line (equal phase line) obtained by connecting points having the same absolute phase Φ obtained by the phase connection processing represents the shape of a cross section obtained by cutting the object to be measured along a certain plane in the same manner as the cutting line in the optical cutting method. Based on this absolute phase Φ, the three-dimensional shape of the object to be measured (height information at each point in the image) can be measured by the principle of triangulation.

而して、正弦波縞の絶対位相値、即ち縞パターンの投影に用いた実体格子上の位置と撮像装置の撮像素子上の結像点位置(画像上の座標)が特定できるので、投影装置と撮像装置の光学的な配置に基づいて三角測量の原理から、画像上の点に対応する被計測物上の投影点の3次元空間での絶対的な座標値(X,Y,Z)を求めれば、被計測物の3次元形状を得ることができる。   Thus, since the absolute phase value of the sine wave fringe, that is, the position on the actual lattice used for the projection of the fringe pattern and the imaging point position (coordinates on the image) on the image pickup device of the image pickup apparatus can be specified. Based on the principle of triangulation based on the optical arrangement of the imaging device, the absolute coordinate value (X, Y, Z) in the three-dimensional space of the projection point on the object to be measured corresponding to the point on the image is obtained. If it calculates | requires, the three-dimensional shape of a to-be-measured object can be obtained.

このように位相シフト法では、得られた画像の各点に対応する3次元座標が簡単な計算処理により求められるとともに高密度の3次元形状の計測データが最低3回の撮像により得られるため、1点あたりの計測時間で評価すると他の計測方法に比べて数倍から数万倍の速度での計測が可能になるという特徴がある。   As described above, in the phase shift method, three-dimensional coordinates corresponding to each point of the obtained image are obtained by a simple calculation process, and measurement data of a high-density three-dimensional shape is obtained by imaging at least three times. When evaluated by the measurement time per point, the measurement can be performed at a speed several to several tens of thousands times faster than other measurement methods.

しかしながら、被計測物の表面に段差や穴があって縞と縞との境界(位相境界)が特定できない場合などには、縞次数nが正しく求められないために位相接続処理が困難になり、正しい距離が得られなくなるという問題(位相飛び問題)が発生するという欠点がある。また、位相シフト法は、なるべく多数の縞を投影し、撮影された画像上において投影縞のコントラストがなるべく高くなるように撮像することで高精度の計測が可能となるが、縞次数が多いと上記位相飛び問題が発生しやすく、高さ計測に必要な絶対位相値を得るのが困難になるという問題がある。   However, when there is a step or a hole on the surface of the object to be measured and the boundary (phase boundary) between the stripes cannot be specified, the phase connection processing becomes difficult because the stripe order n cannot be obtained correctly, There is a disadvantage that a problem that a correct distance cannot be obtained (phase jump problem) occurs. In addition, the phase shift method projects as many fringes as possible and takes an image so that the contrast of the projected fringes is as high as possible on the captured image. There is a problem that the phase jump problem is likely to occur and it is difficult to obtain an absolute phase value necessary for height measurement.

そこで従来より、位相飛び問題を解決する3次元形状計測装置や3次元形状計測方法が種々提案されている(特許文献1,2参照)。特許文献1に記載された方法では、基準正弦波とその整数倍の波長をもつ正弦波を重畳させて投影し、各々の波長で求められた相対位相の情報を統合することで位相境界位置を一意に得ている。また、特許文献2に記載された方法では、所謂空間コード法と位相シフト法を組み合わせ、縞次数nを確定するための空間コードパターンを、縞パターンを投影する光の波長と異なる波長の光で縞パターンと同時に投影し、縞パターンと空間コードパターンとが同時に投影された撮影画像を、光の波長に基づいて縞パターンが投影された画像と空間コードパターンが投影された画像とに分離し、空間コードパターンが投影された複数枚の画像から縞次数nを確定している。尚、空間コードパターンとは空間をコード化するためのものであって、例えば、T周期目の縞パターンに対しては、Tの2進数表現に対応して、ビット値が0なら暗パターン、ビット値が1なら明パターンとして構成された明暗パターンであり、最下位ビットに対する明暗パターンから順番に投影される。
特許3199041号公報 特開2006−177781号公報
Therefore, various three-dimensional shape measuring apparatuses and three-dimensional shape measuring methods for solving the phase skip problem have been proposed (see Patent Documents 1 and 2). In the method described in Patent Document 1, a reference sine wave and a sine wave having an integral multiple of the reference sine wave are superimposed and projected, and information on the relative phase obtained at each wavelength is integrated to determine the phase boundary position. Get uniquely. Further, in the method described in Patent Document 2, a so-called spatial code method and a phase shift method are combined, and a spatial code pattern for determining the fringe order n is obtained by light having a wavelength different from the wavelength of the light that projects the fringe pattern. Projecting simultaneously with the fringe pattern, and separating the captured image in which the fringe pattern and the spatial code pattern are simultaneously projected into an image on which the fringe pattern is projected based on the wavelength of light and an image on which the spatial code pattern is projected, The stripe order n is determined from a plurality of images onto which the spatial code pattern is projected. The space code pattern is for coding a space. For example, for a stripe pattern in the T period, a dark pattern if the bit value is 0, corresponding to the binary representation of T, If the bit value is 1, it is a light / dark pattern configured as a light pattern, and is projected in order from the light / dark pattern for the least significant bit.
Japanese Patent No. 399041 JP 2006-177771 A

しかしながら、特許文献1に記載されている従来例では、1回の計測において必要な画像の枚数(撮像装置による撮像回数)が増加してしまうために計測に要する時間が長くなってしまう(例えば、特許文献1では8回の撮像が必要である)。一方、特許文献2に記載されている従来例では、特許文献1に記載されている従来例と比較して少ない枚数(撮像回数)の画像で計測可能ではあるが、縞パターンを投影する光の波長と異なる波長の光で空間コードパターンを同時に投影するためにカラーパターンが投影可能な投影装置と、カラー画像が撮像可能な撮像装置が必要であり、モノクロ画像によって計測する場合に比べてコストが上昇してしまうという問題がある。   However, in the conventional example described in Patent Document 1, the number of images required for one measurement (the number of times of image pickup by the image pickup apparatus) increases, so that the time required for measurement becomes long (for example, In Patent Document 1, eight times of imaging are required). On the other hand, in the conventional example described in Patent Document 2, it is possible to measure with a smaller number of images (number of times of imaging) than in the conventional example described in Patent Document 1, but the light that projects the fringe pattern is used. In order to simultaneously project a spatial code pattern with light of a wavelength different from the wavelength, a projection device capable of projecting a color pattern and an imaging device capable of capturing a color image are required, and costs are lower than when measuring with a monochrome image. There is a problem of rising.

本発明は、上記の点に鑑みて為されたもので、コスト上昇を抑えながら比較的に短時間で被計測物の3次元形状を計測できる3次元形状計測装置及び3次元形状計測方法を提供することを目的とする。   The present invention has been made in view of the above points, and provides a three-dimensional shape measuring apparatus and a three-dimensional shape measuring method capable of measuring a three-dimensional shape of an object to be measured in a relatively short time while suppressing an increase in cost. The purpose is to do.

請求項1の発明は、上記目的を達成するために、被計測物に任意パターンの光を投影する投影手段と、投影手段を制御して所定の光パターンから成る投影パターンを被計測物に投影させる投影パターン制御手段と、被計測物を撮像する撮像手段と、撮像手段の撮像画像から投影パターンが投影された被計測物の濃淡画像を取得する画像取得手段と、画像取得手段で取得した濃淡画像内の任意の位置における投影パターンの相対位相を演算する相対位相演算手段と、任意位置の相対位相を位相接続して投影パターンの絶対位相を演算する絶対位相演算手段と、絶対位相から被計測物の3次元座標を演算する3次元座標演算手段とを備え、投影パターン制御手段は、光の強度を正弦波状且つ既知量位相をシフトして変化させた複数種類の縞パターンにおいて各々の振幅を1周期毎に変化させた投影パターンを生成して投影手段より被計測物に投影させ、相対位相演算手段は、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて相対位相を演算し、絶対位相演算手段は、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて投影パターンの振幅を演算するとともに、当該振幅から周期を推定し、相対位相を位相接続して絶対位相を演算することを特徴とする。   In order to achieve the above object, the invention of claim 1 projects a projection pattern that projects an arbitrary pattern of light onto the object to be measured and a projection pattern comprising a predetermined light pattern by controlling the projection means on the object to be measured. A projection pattern control means for imaging, an imaging means for imaging the measurement object, an image acquisition means for acquiring a grayscale image of the measurement object on which the projection pattern is projected from a captured image of the imaging means, and the density acquired by the image acquisition means Relative phase calculation means for calculating the relative phase of the projection pattern at an arbitrary position in the image, absolute phase calculation means for calculating the absolute phase of the projection pattern by connecting the relative phases of the arbitrary positions, and measurement from the absolute phase A three-dimensional coordinate calculation means for calculating the three-dimensional coordinates of the object, and the projection pattern control means includes a plurality of types of fringe patterns in which the intensity of light is changed by shifting the intensity of the sine wave and the known phase. In FIG. 5, a projection pattern in which each amplitude is changed for each period is generated and projected onto the measurement object by the projection means, and the relative phase calculation means projects the projection pattern on the grayscale image of the measurement object imaged. The relative phase is calculated based on the density value, and the absolute phase calculation means calculates the amplitude of the projection pattern based on the density value in the grayscale image of the measured object projected by projecting the projection pattern, and from the amplitude It is characterized in that the period is estimated and the relative phase is connected in phase to calculate the absolute phase.

請求項2の発明は、上記目的を達成するために、被計測物に任意パターンの光を投影する投影手段と、投影手段を制御して所定の光パターンから成る投影パターンを被計測物に投影させる投影パターン制御手段と、被計測物を撮像する撮像手段と、撮像手段の撮像画像から投影パターンが投影された被計測物の濃淡画像を取得する画像取得手段と、画像取得手段で取得した濃淡画像内の任意の位置における投影パターンの相対位相を演算する相対位相演算手段と、任意位置の相対位相を位相接続して投影パターンの絶対位相を演算する絶対位相演算手段と、絶対位相から被計測物の3次元座標を演算する3次元座標演算手段とを備え、投影パターン制御手段は、光の強度を正弦波状且つ既知量位相をシフトして変化させた複数種類の縞パターンのうち、少なくとも1種類以上の縞パターンにおいて振幅を周期に応じて変化させた投影パターンと、残りの縞パターンにおいて振幅を周期に応じて前記投影パターンとは異なる態様で変化させた投影パターンと、縞パターンの振幅中心値から成る均一な投影パターンとを生成して投影手段より被計測物に投影させ、相対位相演算手段は、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて相対位相を演算し、絶対位相演算手段は、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて投影パターンの振幅を演算するとともに、当該振幅から周期を推定し、相対位相を位相接続して絶対位相を演算することを特徴とする。   According to a second aspect of the present invention, in order to achieve the above object, a projection unit that projects an arbitrary pattern of light onto the object to be measured, and a projection pattern composed of a predetermined light pattern is projected onto the object to be measured by controlling the projection unit. A projection pattern control means for imaging, an imaging means for imaging the measurement object, an image acquisition means for acquiring a grayscale image of the measurement object on which the projection pattern is projected from a captured image of the imaging means, and the density acquired by the image acquisition means Relative phase calculation means for calculating the relative phase of the projection pattern at an arbitrary position in the image, absolute phase calculation means for calculating the absolute phase of the projection pattern by connecting the relative phases of the arbitrary positions, and measurement from the absolute phase A three-dimensional coordinate calculation means for calculating the three-dimensional coordinates of the object, and the projection pattern control means includes a plurality of types of fringe patterns in which the intensity of light is changed by shifting the intensity of the sine wave and the known phase. Among them, a projection pattern in which the amplitude is changed according to the period in at least one type of stripe pattern, and a projection pattern in which the amplitude is changed in a manner different from the projection pattern according to the period in the remaining stripe pattern, A uniform projection pattern consisting of the center value of the amplitude of the fringe pattern is generated and projected onto the object to be measured by the projecting means, and the relative phase calculating means projects the projection pattern onto the grayscale image of the object to be imaged. The relative phase is calculated based on the value, and the absolute phase calculating means calculates the amplitude of the projection pattern based on the density value in the grayscale image of the object to be measured that is projected by projecting the projection pattern, and the period from the amplitude. And calculating the absolute phase by connecting the relative phases in phase.

請求項3の発明は、請求項1又は2の発明において、画像取得手段は、撮像手段の撮像画像から投影パターンが投影されていない状態の被計測物の濃淡画像を取得する無パターン画像取得手段を備えたことを特徴とする。   According to a third aspect of the present invention, in the first or second aspect of the invention, the image acquisition means acquires a grayscale image of the object to be measured in a state where the projection pattern is not projected from the captured image of the imaging means. It is provided with.

請求項4の発明は、請求項1乃至3の何れか1項の発明において、前記投影パターン制御手段は、光の強度を正弦波状且つ等間隔に位相をシフトして変化させた複数種類の縞パターンから投影パターンを生成することを特徴とする。   According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the projection pattern control means is a plurality of types of stripes in which the intensity of light is changed by shifting the phase in a sine wave shape and at equal intervals. A projection pattern is generated from the pattern.

請求項5の発明は、上記目的を達成するために、所定の光パターンから成る投影パターンを被計測物に投影し、投影パターンを投影した被計測物の濃淡画像を取得し、投影パターンを投影したときの濃淡画像内の任意の位置における投影パターンの相対位相を演算し、任意位置の相対位相を位相接続して投影パターンの絶対位相を演算し、絶対位相から被計測物の3次元座標を演算することで被計測物の3次元形状を計測する3次元形状計測方法であって、光の強度を正弦波状且つ既知量位相をシフトして変化させた複数種類の縞パターンにおいて各々の振幅を1周期毎に変化させた投影パターンを生成して被計測物に投影する過程と、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて相対位相を演算する過程と、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて投影パターンの振幅を演算するとともに、当該振幅から周期を推定し、相対位相を位相接続して絶対位相を演算する過程とを有することを特徴とする。   In order to achieve the above object, the invention according to claim 5 projects a projection pattern composed of a predetermined light pattern onto the measurement object, obtains a grayscale image of the measurement object on which the projection pattern is projected, and projects the projection pattern. The relative phase of the projection pattern at an arbitrary position in the grayscale image is calculated, the absolute phase of the projection pattern is calculated by connecting the relative phases of the arbitrary positions in phase, and the three-dimensional coordinates of the object to be measured are calculated from the absolute phase. A three-dimensional shape measuring method for measuring a three-dimensional shape of an object to be measured by calculating, wherein each amplitude is measured in a plurality of types of fringe patterns in which the intensity of light is changed by shifting the phase of a sine wave and a known amount of phase. A process of generating a projection pattern changed every cycle and projecting it onto the measurement object, and an excessive calculation of the relative phase based on the density value in the grayscale image of the measurement object imaged by projecting the projection pattern. And calculating the amplitude of the projection pattern based on the density value in the grayscale image of the object measured by projecting the projection pattern, estimating the period from the amplitude, and connecting the relative phase in phase to obtain the absolute phase. And a process of calculating.

請求項6の発明は、上記目的を達成するために、所定の光パターンから成る投影パターンを被計測物に投影し、投影パターンを投影した被計測物の濃淡画像を取得し、投影パターンを投影したときの濃淡画像内の任意の位置における投影パターンの相対位相を演算し、任意位置の相対位相を位相接続して投影パターンの絶対位相を演算し、絶対位相から被計測物の3次元座標を演算することで被計測物の3次元形状を計測する3次元形状計測方法であって、光の強度を正弦波状且つ既知量位相をシフトして変化させた複数種類の縞パターンのうち、少なくとも1種類以上の縞パターンにおいて振幅を周期に応じて変化させた投影パターンと、残りの縞パターンにおいて振幅を周期に応じて前記投影パターンとは異なる態様で変化させた投影パターンと、縞パターンの振幅中心値から成る均一な投影パターンとを生成して被計測物に投影する過程と、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて相対位相を演算する過程と、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて投影パターンの振幅を演算するとともに、当該振幅から周期を推定し、相対位相を位相接続して絶対位相を演算する過程とを有することを特徴とする。   In order to achieve the above object, the invention of claim 6 projects a projection pattern composed of a predetermined light pattern onto the measurement object, obtains a grayscale image of the measurement object on which the projection pattern is projected, and projects the projection pattern. The relative phase of the projection pattern at an arbitrary position in the grayscale image is calculated, the absolute phase of the projection pattern is calculated by connecting the relative phases of the arbitrary positions in phase, and the three-dimensional coordinates of the object to be measured are calculated from the absolute phase. A three-dimensional shape measurement method for measuring a three-dimensional shape of an object to be measured by calculating, wherein at least one of a plurality of types of fringe patterns in which the intensity of light is changed by shifting the intensity of a sine wave and a known amount phase. A projection pattern in which the amplitude is changed according to the period in the stripe pattern of more than one type, and a projection pattern in which the amplitude is changed in a different manner from the projection pattern in accordance with the period in the remaining stripe pattern. Based on the density value in the grayscale image of the object measured by projecting the projection pattern and generating a uniform projection pattern consisting of the center of amplitude of the fringe pattern and projecting it onto the object. Calculating the relative phase, and calculating the amplitude of the projection pattern based on the density value in the grayscale image of the measured object projected by projecting the projection pattern, estimating the period from the amplitude, and calculating the relative phase. And a step of calculating an absolute phase by connecting the phases.

請求項7の発明は、請求項5又は6の発明において、投影パターンを投影した被計測物の濃淡画像を取得する過程において、投影パターンを投影していない状態の被計測物の濃淡画像を取得する過程を有することを特徴とする。   The invention according to claim 7 is the invention according to claim 5 or 6, wherein in the process of obtaining the gray image of the measurement object on which the projection pattern is projected, the gray image of the measurement object in a state where the projection pattern is not projected is obtained. It has the process to perform.

請求項8の発明は、請求項5乃至7の何れか1項の発明において、前記投影パターン制御手段は、光の強度を正弦波状且つ等間隔に位相をシフトして変化させた複数種類の縞パターンから投影パターンを生成することを特徴とする。   The invention according to claim 8 is the invention according to any one of claims 5 to 7, wherein the projection pattern control means is a plurality of types of stripes in which the intensity of light is changed by shifting the phase in a sine wave shape and at equal intervals. A projection pattern is generated from the pattern.

請求項1,5の発明によれば、位相シフト法を利用した3次元形状計測において必須となる正弦波状の縞パターンの各々において、1周期毎に振幅を変化させた投影パターンを生成して被計測物に投影しているため、周期毎の振幅の違いから周期を推定して相対位相を位相接続できるから、従来例のように高価な投影装置や撮像装置を用いる必要が無く、その結果、表面に段差や孔がある物体の3次元形状をコスト上昇を抑えながら少ない撮像回数で計測することができる。   According to the first and fifth aspects of the present invention, in each of the sinusoidal fringe patterns essential in the three-dimensional shape measurement using the phase shift method, a projection pattern with the amplitude changed for each period is generated to be covered. Since it is projected onto the measurement object, the period can be estimated from the difference in amplitude for each period and the relative phase can be connected in phase, so there is no need to use an expensive projection device or imaging device as in the conventional example, and as a result, The three-dimensional shape of an object having a step or a hole on the surface can be measured with a small number of imaging operations while suppressing an increase in cost.

請求項2,6の発明によれば、位相シフト法を利用した3次元形状計測において必須となる正弦波状の縞パターンの各々において、少なくとも1種類以上の縞パターンにおいて振幅を周期に応じて変化させた投影パターンと、残りの縞パターンにおいて振幅を周期に応じて前記投影パターンとは異なる態様で変化させた投影パターンと、縞パターンの振幅中心値から成る均一な投影パターンとを生成して投影手段より被計測物に投影させるため、周期毎の振幅の違いから周期を推定して相対位相を位相接続できるから、従来例のように高価な投影装置や撮像装置を用いる必要が無く、その結果、表面に段差や孔のある物体の3次元形状をコスト上昇を抑えながら少ない撮像回数で計測することができる。また、振幅が互いに異なる投影パターンを組み合わせて周期を推定するので、振幅の種類が少なくても多くの周期を推定することができ、したがって小さい振幅での位相検出を回避することができ、位相の検出精度が低下するのを防ぐことができる。   According to the second and sixth aspects of the present invention, in each of the sinusoidal fringe patterns essential for the three-dimensional shape measurement using the phase shift method, the amplitude is changed in accordance with the period in at least one kind of fringe pattern. Projecting means for generating a projected pattern, a projected pattern in which the amplitude of the remaining fringe pattern is changed in a manner different from that of the projected pattern according to the period, and a uniform projected pattern composed of the amplitude center value of the fringe pattern Since the relative phase can be phase-connected by estimating the period from the difference in amplitude for each period in order to project onto the object to be measured more, there is no need to use an expensive projection apparatus or imaging apparatus as in the conventional example, and as a result, The three-dimensional shape of an object having a step or a hole on the surface can be measured with a small number of imaging operations while suppressing an increase in cost. In addition, since the period is estimated by combining projection patterns having different amplitudes, it is possible to estimate many periods even if the number of types of amplitude is small, thus avoiding phase detection with a small amplitude, It can prevent that detection accuracy falls.

請求項3,7の発明によれば、被計測物に照射されている投影装置から投影パターンとして照射される光以外の光を考慮して3次元形状を計測することができるので、暗室等の周囲の光を遮断した場所を用意せずに計測することができる。   According to the third and seventh aspects of the present invention, it is possible to measure a three-dimensional shape in consideration of light other than light irradiated as a projection pattern from the projection device irradiated to the object to be measured. Measurements can be made without preparing a place that blocks ambient light.

請求項4,8の発明によれば、等間隔に位相をシフトさせた複数種類の縞パターンから投影パターンを生成するので、周期を推定するために必要な演算を既知量位相をシフトさせた場合と比べて容易に行うことができる。   According to the fourth and eighth aspects of the invention, since the projection pattern is generated from a plurality of types of fringe patterns whose phases are shifted at equal intervals, the calculation necessary for estimating the period is shifted by a known amount phase. This can be done more easily than

以下、図面を参照して本発明を実施形態により詳細に説明する。   Hereinafter, the present invention will be described in detail with reference to the drawings.

(実施形態1)
本実施形態の3次元形状計測装置は、図1に示すように、被計測物Mに任意パターンの光を投影する投影装置1と、被計測物Mを撮像する撮像装置2と、投影装置1及び撮像装置2を制御するとともに撮像装置2で撮像した撮像画像に対して画像処理を行う画像処理装置3とで構成される。
(Embodiment 1)
As shown in FIG. 1, the three-dimensional shape measurement apparatus of the present embodiment includes a projection apparatus 1 that projects light of an arbitrary pattern onto the measurement object M, an imaging apparatus 2 that images the measurement object M, and the projection apparatus 1. And an image processing device 3 that controls the imaging device 2 and performs image processing on a captured image captured by the imaging device 2.

投影装置1は、光源10と、光源10の前方に配置された透過型の液晶パネル11と、液晶パネル11を通過した光を被計測物Mの表面に集光するレンズ12とを有した所謂液晶プロジェクタから成る。また、撮像装置2は、CCDやCMOS等の固体撮像素子、被写体の像を固体撮像素子の撮像面に結像させる光学系、固体撮像素子の出力を信号処理して画素毎の輝度(濃度値)を得る信号処理回路等で構成された、所謂モノクロ型のスチルカメラである。画像処理装置3は、CPU、メモリ、ディスプレイ、ハードディスク等の記憶装置、入出力用の各種インタフェース等を具備する汎用のコンピュータ(ハードウェア)と、本発明に係る3次元形状計測方法をコンピュータに実行させる3次元形状計測用プログラム(ソフトウェア)で構成され、当該3次元形状計測用プログラムをCPUで実行することにより、投影パターン制御手段30、画像取得手段31、無パターン画像取得手段32、相対位相演算手段33、絶対位相演算手段34、3次元座標演算手段35の各手段を実現している。   The projection device 1 includes a light source 10, a transmissive liquid crystal panel 11 disposed in front of the light source 10, and a so-called lens 12 that condenses the light that has passed through the liquid crystal panel 11 on the surface of the measurement object M. It consists of a liquid crystal projector. In addition, the imaging device 2 is a solid-state imaging device such as a CCD or CMOS, an optical system that forms an image of a subject on the imaging surface of the solid-state imaging device, and performs signal processing on the output of the solid-state imaging device to obtain a luminance (density value) ) Is a so-called monochrome type still camera. The image processing apparatus 3 executes a general-purpose computer (hardware) including a CPU, a memory, a display, a storage device such as a hard disk, various input / output interfaces, and the three-dimensional shape measurement method according to the present invention. 3D shape measurement program (software) to be executed, and by executing the 3D shape measurement program on the CPU, the projection pattern control means 30, the image acquisition means 31, the non-pattern image acquisition means 32, the relative phase calculation Means 33, absolute phase calculation means 34, and three-dimensional coordinate calculation means 35 are realized.

投影パターン制御手段30は、後述する投影パターンを生成して記憶装置に予め記憶するとともに必要に応じて記憶した投影パターンのデータを読み出し、例えば、DVI(Digital Visual Interface)のような汎用のディスプレイ用インタフェースを介して投影パターンのデータを投影装置1に伝送するとともに、RS232CやIEEE488等の汎用の通信インタフェースを介して投影装置1の動作(光源10の点灯・消灯や光量調整等)を制御する機能を有している。尚、投影装置1では投影パターンデータに基づいて液晶パネル11に投影パターンを表示させる。   The projection pattern control means 30 generates a projection pattern, which will be described later, and stores it in a storage device in advance and reads out the stored projection pattern data as necessary, for example, for a general-purpose display such as DVI (Digital Visual Interface). A function of transmitting projection pattern data to the projection apparatus 1 via the interface and controlling the operation of the projection apparatus 1 (turning on / off the light source 10, adjusting the light amount, etc.) via a general-purpose communication interface such as RS232C or IEEE488. have. The projection apparatus 1 displays a projection pattern on the liquid crystal panel 11 based on the projection pattern data.

また、画像取得手段31は、撮像装置2で標本化並びに量子化されたディジタルの画像信号を取り込むとともに、取り込んだ画像信号から各画素の輝度(濃度値)で表される画像データを取得してメモリに記憶する機能を有している。尚、画像取得手段31は、RS232CやIEEE488等の汎用の通信インタフェースを介して撮像装置2の動作(撮像のタイミング等)を制御する機能や、投影パターン制御手段30に対して投影装置1に投影パターンを投影させるように指示する機能も有している。   The image acquisition means 31 acquires a digital image signal sampled and quantized by the imaging device 2 and acquires image data represented by luminance (density value) of each pixel from the acquired image signal. It has a function of storing in a memory. Note that the image acquisition unit 31 functions to control the operation of the imaging device 2 (imaging timing, etc.) via a general-purpose communication interface such as RS232C or IEEE488, and projects the projection pattern control unit 30 onto the projection device 1. It also has a function of instructing to project a pattern.

無パターン画像取得手段32は、投影装置1から投影パターンが投影されていない状態において撮像装置2で撮像された画像信号を取り込んで画像データを取得するとともにメモリに記憶する機能を有している。つまり、被計測物Mには投影装置1から投影パターンとして照射される光以外の光(以下、このような光を「環境光」と呼ぶ)も照射されており、無パターン画像取得手段32では、環境光のみが照射されているときの被計測物Mの画像データを取得している。   The non-pattern image acquisition means 32 has a function of acquiring an image data by acquiring an image signal captured by the imaging device 2 in a state where a projection pattern is not projected from the projection device 1 and storing the image data in a memory. That is, the measurement object M is also irradiated with light other than the light irradiated as a projection pattern from the projection apparatus 1 (hereinafter, such light is referred to as “environment light”). The image data of the measurement object M when only ambient light is irradiated is acquired.

相対位相演算手段33は、従来技術で説明した相対位相φを演算により求める機能を有する。また、絶対位相演算手段34は、後述するように縞次数nを確定するとともに確定した縞次数nと相対位相φとを用いて絶対位相Φ(=φ+2nπ)を演算により求める機能を有している。更に、3次元座標演算手段35は、画像上の点p(u,v)に対応する被計測物M上の投影点P(X,Y,Z)の3次元座標を演算により求める機能を有しており、3次元座標演算手段35で求めた3次元座標から被計測物Mの3次元形状を得る(計測する)ことができる。   The relative phase calculation means 33 has a function of calculating the relative phase φ described in the prior art by calculation. The absolute phase calculation means 34 has a function of determining the fringe order n and calculating the absolute phase Φ (= φ + 2nπ) by using the determined fringe order n and the relative phase φ as will be described later. . Further, the three-dimensional coordinate calculation means 35 has a function of calculating the three-dimensional coordinates of the projection point P (X, Y, Z) on the measurement object M corresponding to the point p (u, v) on the image by calculation. Thus, the three-dimensional shape of the measurement object M can be obtained (measured) from the three-dimensional coordinates obtained by the three-dimensional coordinate calculation means 35.

ここで本実施形態では、光の強度を正弦波状且つπ/2ずつ位相をシフトして変化させた4種類(0,π/2,π,3π/2)の各々の縞パターンにおいて、以下の表1に示すように1周期毎に正弦波の振幅Aを変化させた4種類の投影パターンを投影パターン制御手段30により生成し、当該投影パターンを投影装置1から被計測物Mに投影させる。 Here, in the present embodiment, in each of four types of stripe patterns (0, π / 2, π, 3π / 2) in which the intensity of light is changed sinusoidally and the phase is shifted by π / 2, the following four types of projection patterns obtained by changing the amplitude a n of the sinusoidal wave in each cycle as shown in Table 1 were produced by a projection pattern control unit 30, to project the projection pattern from the projection apparatus 1 to the measured object M .

Figure 0005032943
Figure 0005032943

4種類の投影パターンP(k=0,1,2,3)並びに縞次数nは次式で表される。但し、Aは正弦波の振幅、Φは絶対位相、Cは正弦波の中心値、[m]はmを超えない最大の整数を示している。 The four types of projection patterns P k (k = 0, 1, 2, 3) and the stripe order n are expressed by the following equations. Where An is the amplitude of the sine wave, Φ is the absolute phase, C is the center value of the sine wave, and [m] is the maximum integer not exceeding m.

Figure 0005032943
Figure 0005032943

ここで、投影装置1において投影可能なパターンが8ビットの画像データで構成されるとしたとき、正弦波の中心値C=125,正弦波の振幅Aの最大値=125とすると、投影パターンPの濃度値を0〜250の範囲で表現できるので、8ビットの画像データとして構成可能である。このときの投影パターンP,P,P,Pの波形を図2(a)〜(d)にそれぞれ示す。 Here, when the projection-pattern in the projection apparatus 1 is to consist of 8-bit image data, the center value C = 125 sine wave, when the maximum value = 125 of the amplitude A n of the sinusoidal, projection pattern since the density value of P k can be expressed in a range of 0 to 250, it can be configured as an 8-bit image data. The waveforms of the projection patterns P 0 , P 1 , P 2 , and P 3 at this time are shown in FIGS.

次に、本実施形態の3次元形状計測装置の動作、即ち、本発明に係る3次元形状計測方法について説明する。先ず、画像処理装置3のCPUで3次元形状計測用プログラムを実行することで3次元形状計測装置が動作を開始すると、画像取得手段31が投影パターン制御手段30に指示を与え、当該指示に従って投影パターン制御手段30が記憶装置に格納されている最初の投影パターンPの画像データをメモリの作業領域に読み出し、更にディスプレイ用インタフェースを介して投影装置1に伝送し、投影装置1を制御して投影パターンPを被計測物Mに投影させる。画像データが投影装置1に伝送された後、画像取得手段31は撮像装置2を制御して投影パターンPが投影された被計測物Mを撮像させ、撮像装置2から出力された画像信号を取り込んで投影パターンPが投影された被計測物Mの画像データを取得してメモリに記憶する。また、画像取得手段31では残り3種類の投影パターンP,P,Pについても順番に投影装置1に投影させ、それぞれの投影パターンP,P,Pが投影された被計測物Mの画像データを取得してメモリに記憶する。 Next, the operation of the three-dimensional shape measurement apparatus of this embodiment, that is, the three-dimensional shape measurement method according to the present invention will be described. First, when the three-dimensional shape measurement apparatus starts operating by executing a three-dimensional shape measurement program on the CPU of the image processing apparatus 3, the image acquisition means 31 gives an instruction to the projection pattern control means 30, and projection is performed according to the instruction. The pattern control means 30 reads the image data of the first projection pattern P 0 stored in the storage device into the work area of the memory, and further transmits it to the projection device 1 via the display interface to control the projection device 1. The projection pattern P 0 is projected onto the measurement object M. After the image data is transmitted to the projection apparatus 1, the image acquisition unit 31 controls the imaging apparatus 2 to image the measurement object M on which the projection pattern P 0 is projected, and outputs the image signal output from the imaging apparatus 2. The image data of the measurement object M on which the projection pattern P 0 is captured and projected is acquired and stored in the memory. In addition, the image acquisition means 31 projects the remaining three types of projection patterns P 1 , P 2 , and P 3 onto the projection device 1 in order, and the projection target P 1 , P 2 , and P 3 are projected to be measured. Image data of the object M is acquired and stored in the memory.

一方、無パターン画像取得手段32は、投影装置1を停止させた状態、つまり、被計測物Mに環境光のみが照射されている状態で撮像装置2に被計測物Mを撮像させて投影パターンPが投影されていない状態の被計測物Mの画像データを取得してメモリに記憶する。 On the other hand, the non-pattern image acquisition unit 32 causes the imaging device 2 to image the measurement object M in a state where the projection apparatus 1 is stopped, that is, in a state where only the environmental light is irradiated to the measurement object M. Image data of the measurement object M in a state where Pk is not projected is acquired and stored in the memory.

投影パターンPが投影された状態で撮像装置2で撮像された画像上の任意の画素(u,v)における輝度(濃度値)I〜Iは、環境光の影響も含めて次式で表される。但し、Eは環境光による輝度、ρは被計測物Mの表面反射率、βは撮像装置2における光電変換係数である。尚、Iは投影パターンPが投影されない状態で撮像装置2で撮像された画像上の任意の画素(u,v)における輝度(濃度値)を表している。 The luminances (density values) I 0 to I 3 at arbitrary pixels (u, v) on the image captured by the imaging device 2 in a state in which the projection pattern P k is projected are expressed by the following formulas including the influence of ambient light. It is represented by However, E is the brightness | luminance by environmental light, (rho) is the surface reflectance of the to-be-measured object M, (beta) is a photoelectric conversion coefficient in the imaging device 2. FIG. I 4 represents the luminance (density value) at an arbitrary pixel (u, v) on the image captured by the imaging device 2 in a state where the projection pattern P k is not projected.

Figure 0005032943
Figure 0005032943

ここで、a=βρA,c=βρC,e=βρEとおくと、各輝度I(k=0,1,2,3,4)は次式で表される。 Here, when a n = βρA n , c = βρC, and e = βρE, each luminance I k (k = 0, 1, 2, 3, 4) is expressed by the following equation.

Figure 0005032943
Figure 0005032943

相対位相演算手段33では、IとI及びIとIのそれぞれの差分値を用いて、次式によって相対位相φの推定値<φ>と正弦波の振幅a(=βρA)の推定値<a>を求める。 Relative phase calculating means 33, using the respective difference values of I 0 and I 2 and I 1 and I 3, the estimated value of the relative phase phi by the following equation <phi> sine wave amplitude a n (= βρA n the estimated value of) obtaining the <a n>.

Figure 0005032943
Figure 0005032943

そして、絶対位相演算手段34では、I〜Iの加算値を用いて、正弦波の中心値c(=βρC)の推定値<c>を次式によって求める。 Then, the absolute phase calculation means 34 obtains an estimated value <c> of the center value c (= βρC) of the sine wave using the addition value of I 0 to I 4 by the following equation.

Figure 0005032943
Figure 0005032943

ここで、絶対位相演算手段34では、正弦波の中心値C、及びその推定値<c>、正弦波の振幅aの推定値<a>を用いて、正弦波の振幅Aの推定値<A>を次式によって求め、表1を参照して正弦波の振幅Aの推定値<A>と対応する縞次数nの推定値<n>を求める。 Here, the absolute phase calculating means 34, the sine wave center value C, and the estimated value <c>, estimate of the amplitude a n sine wave using <a n>, the estimation of the amplitude A n of the sinusoidal obtains the value <A n> by the following equation, the estimated value of the fringe order n corresponding to the estimated value <A n> of the amplitude a n of the sine wave with reference to Table 1 Request <n>.

Figure 0005032943
Figure 0005032943

更に、絶対位相演算手段34は、相対位相φの推定値<φ>と縞次数nの推定値<n>とから絶対位相Φの推定値<Φ>を次式によって求める。   Further, the absolute phase calculation means 34 obtains the estimated value <Φ> of the absolute phase Φ from the estimated value <φ> of the relative phase φ and the estimated value <n> of the fringe order n by the following equation.

Figure 0005032943
Figure 0005032943

そして、3次元座標演算手段35において絶対位相の推定値<Φ>から三角測量の原理により各画素(u,v)での高さ情報(3次元空間における各画素の座標値)を求めるとともに、各画素(u,v)に対応する被計測物M上の投影点の3次元空間での絶対的な座標値を求めれば、被計測物Mの3次元形状を得ることができる。   Then, the three-dimensional coordinate calculation means 35 obtains height information (coordinate values of each pixel in the three-dimensional space) at each pixel (u, v) from the absolute phase estimated value <Φ> by the principle of triangulation. If the absolute coordinate value in the three-dimensional space of the projection point on the measurement object M corresponding to each pixel (u, v) is obtained, the three-dimensional shape of the measurement object M can be obtained.

上述のように、本実施形態によれば、位相シフト法を利用した3次元形状計測において必須となる正弦波状の縞パターンの各々において、1周期毎に正弦波の振幅Aを変化させた投影パターンを生成して被計測物Mに投影しているため、周期毎の正弦波の振幅Aの違いから周期を推定して相対位相を位相接続できるから、特許文献2に記載されている従来例のように高価な投影装置や撮像装置を用いる必要が無く、その結果、表面に段差や孔のある物体の3次元形状をコスト上昇を抑えながら少ない撮像回数(本実施形態では5回)で計測することができる。 As described above, according to this embodiment, the projection at each of the sinusoidal fringe pattern is essential in the three-dimensional shape measurement using the phase shift method, which changes the amplitude A n of the sine wave in each cycle since the generated pattern is projected on the measured object M, since the relative phase can be phase connection by estimating the period from the difference of the amplitude a n of the sine wave of each cycle, conventionally as described in Patent Document 2 There is no need to use an expensive projection device or imaging device as in the example, and as a result, the three-dimensional shape of an object having a step or a hole on the surface is reduced in the number of times of imaging (5 times in this embodiment) while suppressing an increase in cost. It can be measured.

ところで、上記では4種類の投影パターンを用いて3次元形状の計測を行ったが、光の強度を正弦波状且つ2π/3ずつ位相をシフトして変化させた3種類(0,2π/3,4π/3)の縞パターンを用いて計測を行ってもよい。この場合、4種類の投影パターンを用いる場合と比較して撮像回数を1回減らすことができる。以下、3種類の縞パターンを用いた場合について説明する。3種類の投影パターンP(k=0,1,2)は次式で表される。 By the way, although the three-dimensional shape was measured using four types of projection patterns in the above, the three types (0, 2π / 3, 3) in which the intensity of light is changed in a sine wave shape and the phase is shifted by 2π / 3. Measurement may be performed using a 4π / 3) stripe pattern. In this case, the number of times of imaging can be reduced by one compared to the case of using four types of projection patterns. Hereinafter, a case where three types of stripe patterns are used will be described. Three types of projection patterns P k (k = 0, 1, 2) are expressed by the following equations.

Figure 0005032943
Figure 0005032943

投影パターンPが投影された状態で撮像装置2で撮像された画像上の任意の画素(u,v)における輝度(濃度値)I〜Iは、環境光の影響も含めて次式で表される。尚、Iは投影パターンPが投影されない状態で撮像装置2で撮像された画像上の任意の画素(u,v)における輝度(濃度値)を表している。 Luminances (density values) I 0 to I 2 at arbitrary pixels (u, v) on the image captured by the imaging device 2 in a state in which the projection pattern P k is projected are expressed by the following equation including the influence of ambient light. It is represented by Note that I 3 represents the luminance (density value) at an arbitrary pixel (u, v) on the image captured by the imaging device 2 in a state where the projection pattern P k is not projected.

Figure 0005032943
Figure 0005032943

ここで、a=βρA,c=βρC,e=βρEとおくと、各輝度I(k=0,1,2,3)は次式で表される。 Here, when a n = βρA n , c = βρC, and e = βρE, each luminance I k (k = 0, 1, 2, 3) is expressed by the following equation.

Figure 0005032943
Figure 0005032943

相対位相演算手段33では、I〜Iを用いて、次式によって相対位相φの推定値<φ>と正弦波の振幅aの推定値<a>を求める。 Relative phase calculating means 33, using I 0 ~I 2, the estimated value of the relative phase phi by the following equation: <phi> an estimate of the amplitude a n of the sinusoidal seek <a n>.

Figure 0005032943
Figure 0005032943

そして、絶対位相演算手段34では、I〜Iの加算値を用いて、正弦波の中心値cの推定値<c>を次式によって求める。 Then, the absolute phase calculation means 34 obtains an estimated value <c> of the center value c of the sine wave by the following formula using the added value of I 0 to I 3 .

Figure 0005032943
Figure 0005032943

ここで、絶対位相演算手段34では、正弦波の中心値C、及びその推定値<c>、正弦波の振幅aの推定値<a>を用いて、正弦波の振幅Aの推定値<A>を上記(2)式によって求め、表1を参照して正弦波の振幅Aの推定値<A>と対応する縞次数nの推定値<n>を求める。更に、絶対位相演算手段34は、相対位相φの推定値<φ>と縞次数nの推定値<n>とから絶対位相Φの推定値<Φ>を上記(3)式によって求める。そして、3次元座標演算手段35において絶対位相の推定値<Φ>から三角測量の原理により各画素(u,v)での高さ情報を求めるとともに、各画素(u,v)に対応する被計測物M上の投影点の3次元空間での絶対的な座標値を求めれば、被計測物Mの3次元形状を得ることができる。 Here, the absolute phase calculating means 34, the sine wave center value C, and the estimated value <c>, estimate of the amplitude a n sine wave using <a n>, the estimation of the amplitude A n of the sinusoidal value <A n> determined by the above equation (2), the estimated value of the fringe order n corresponding to the estimated value <A n> of the amplitude a n of the sine wave with reference to Table 1 Request <n>. Further, the absolute phase calculation means 34 obtains the estimated value <Φ> of the absolute phase Φ from the estimated value <φ> of the relative phase φ and the estimated value <n> of the fringe order n by the above equation (3). Then, the three-dimensional coordinate calculation means 35 obtains height information at each pixel (u, v) from the absolute phase estimated value <Φ> by the principle of triangulation, and the object corresponding to each pixel (u, v). If the absolute coordinate value in the three-dimensional space of the projection point on the measurement object M is obtained, the three-dimensional shape of the measurement object M can be obtained.

尚、暗室での計測等のように、環境光が無い、即ちE=0と近似できる場合には、無パターン画像取得手段32を必要とせず、上記の4種類の投影パターンを用いる場合及び3種類の投影パターンを用いる場合の何れにおいても撮像回数を1回減らすことができる。環境光が無い場合には、上記4種類の投影パターンを用いる計測においては、E=0,e=0,I=0として各計算を行い、上記3種類の投影パターンを用いる計測においては、E=0,e=0,I=0として各計算を行えばよい。 When there is no ambient light, that is, it can be approximated to E = 0, as in measurement in a dark room, the patternless image acquisition unit 32 is not required and the above four types of projection patterns are used. In any case of using different types of projection patterns, the number of times of imaging can be reduced by one. When there is no ambient light, in the measurement using the four types of projection patterns, each calculation is performed with E = 0, e = 0, and I 4 = 0. In the measurement using the three types of projection patterns, Each calculation may be performed with E = 0, e = 0, and I 3 = 0.

また、被計測物Mの表面反射率ρ、撮像装置2における光電変換係数βが既知であれば、正弦波の振幅aの推定値<a>が求まれば(1)式から正弦波の振幅Aの推定値<A>を求めることができるので、上記の4種類の投影パターンを用いる場合及び3種類の投影パターンを用いる場合の何れにおいても、正弦波の中心値cの推定値<c>を求める過程を必要とせず、したがって無パターン画像取得手段32を必要としないために、環境光が有る場合において撮像回数を1回減らすことができる。 The surface reflectance of the object to be measured M [rho, sine wave from long photoelectric conversion coefficient β is known in the imaging apparatus 2, if the estimated value of the amplitude a n sine wave <a n> Motomare (1) it is possible to the obtain an amplitude a n estimate <A n of>, in any case of using a case and three projection pattern using four types of projection patterns of the well, the estimation of the center value c of the sine wave Since the process for obtaining the value <c> is not required, and thus the non-pattern image acquisition means 32 is not required, the number of times of imaging can be reduced by one in the presence of ambient light.

ところで、上記では正弦波の振幅Aと縞次数nとの関係を表1のように定義したが、正弦波の振幅Aの1周期毎の変化を縞次数n、振幅変化係数αを用いて次式のように定義してもよい。 Incidentally, in the above, but the relationship between the amplitude A n and fringe order n sine wave was defined as shown in Table 1, line order n changes in every period of the amplitude A n of the sine wave, the amplitude change coefficient α using May be defined as:

Figure 0005032943
Figure 0005032943

この場合、上記の式と(2)式から縞次数nの推定値<n>は次式で表される。尚、‖m‖はmに最も近い整数を示している。   In this case, the estimated value <n> of the stripe order n is expressed by the following equation from the above equation and the equation (2). In addition, を m を indicates an integer closest to m.

Figure 0005032943
Figure 0005032943

而して、振幅変化係数αを適宜変更することで、正弦波の振幅Aの1周期毎に種々変化させた投影パターンを用いて計測することができる。 And Thus, by changing the amplitude change coefficient α appropriately, can be measured using the projection pattern was varied for each cycle of the amplitude A n of the sine wave.

(実施形態2)
本実施形態の3次元形状計測装置は、投影パターン制御手段30が実施形態1とは異なる投影パターンを生成する点で相違しているが、装置の構成は実施形態1と共通であるので、実施形態1と共通する構成要素には同一の符号を付して説明を省略する。また、3次元形状計測方法に関しても実施形態1と共通であるので、実施形態1と共通する点については説明を省略する。
(Embodiment 2)
The three-dimensional shape measurement apparatus of the present embodiment is different in that the projection pattern control unit 30 generates a projection pattern different from that of the first embodiment, but the configuration of the apparatus is the same as that of the first embodiment. Constituent elements common to the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Further, the three-dimensional shape measurement method is also common to the first embodiment, and thus the description of the points common to the first embodiment is omitted.

本実施形態においては、光の強度を正弦波状且つπ/2ずつ位相をシフトして変化させた4種類(0,π/2,π,3π/2)の各々の縞パターンにおいて、周期に応じて正弦波の振幅Aを変化させた2種類(0,π/2)の投影パターン、及び周期に応じて正弦波の振幅Bを変化させた残りの2種類(π,3π/2)の投影パターン、並びに正弦波の中心値Cから成る均一な投影パターンを投影パターン制御手段30により生成し、当該投影パターンを投影装置1から被計測物Mに投影させる。尚、以下の表2に示すように、正弦波の振幅A,Bは、周期に応じて互いに異なる変化をするように定義している。 In the present embodiment, each of four types of stripe patterns (0, π / 2, π, 3π / 2) in which the intensity of light is changed sinusoidally and shifted in phase by π / 2, according to the period. two of changing the amplitude a n of the sinusoidal Te (0, π / 2) projection pattern, and the remaining two of changing the amplitude B n of the sine wave in accordance with the period of the (π, 3π / 2) The projection pattern control means 30 generates a uniform projection pattern composed of the projection pattern 1 and the center value C of the sine wave, and projects the projection pattern from the projection apparatus 1 onto the measurement object M. As shown in Table 2 below, the amplitudes A n and B n of the sine wave are defined to change differently according to the period.

Figure 0005032943
Figure 0005032943

4種類の投影パターンP(k=0,1,2,3)並びに縞次数nは次式で表される。但し、A,Bは正弦波の振幅、Φは絶対位相、Cは正弦波の中心値、[m]はmを超えない最大の整数を示している。 The four types of projection patterns P k (k = 0, 1, 2, 3) and the stripe order n are expressed by the following equations. Where A n and B n are amplitudes of the sine wave, Φ is an absolute phase, C is a center value of the sine wave, and [m] is a maximum integer not exceeding m.

Figure 0005032943
Figure 0005032943

ここで、投影装置1において投影可能なパターンが8ビットの画像データで構成されるとしたとき、正弦波の中心値C=125,正弦波の振幅A,Bの最大値=125とすると、投影パターンPの濃度値を0〜250の範囲で表現できるので、8ビットの画像データとして構成可能である。このときの投影パターンP,P,P,P,Pの波形を図3(a)〜(e)にそれぞれ示す。 Here, assuming that the pattern that can be projected by the projection apparatus 1 is composed of 8-bit image data, assuming that the sine wave center value C = 125 and the maximum values of the sine wave amplitudes A n and B n = 125. Since the density value of the projection pattern Pk can be expressed in the range of 0 to 250, it can be configured as 8-bit image data. The waveforms of the projection patterns P 0 , P 1 , P 2 , P 3 and P 4 at this time are shown in FIGS. 3 (a) to 3 (e), respectively.

投影パターンPが投影された状態で撮像装置2で撮像された画像上の任意の画素(u,v)における輝度(濃度値)I〜Iは、環境光の影響も含めて次式で表される。但し、Eは環境光による輝度、ρは被計測物Mの表面反射率、βは撮像装置2における光電変換係数である。尚、Iは投影パターンPが投影されない状態で撮像装置2で撮像された画像上の任意の画素(u,v)における輝度(濃度値)を表している。 The luminances (density values) I 0 to I 4 at arbitrary pixels (u, v) on the image captured by the imaging device 2 in the state in which the projection pattern P k is projected are expressed by the following equations including the influence of ambient light. It is represented by However, E is the brightness | luminance by environmental light, (rho) is the surface reflectance of the to-be-measured object M, (beta) is a photoelectric conversion coefficient in the imaging device 2. FIG. Note that I 5 represents the luminance (density value) at an arbitrary pixel (u, v) on the image captured by the imaging device 2 in a state where the projection pattern P k is not projected.

Figure 0005032943
Figure 0005032943

ここで、a=βρA,b=βρB,c=βρC,e=βρEとおくと、各輝度I(k=0,1,2,3,4,5)は次式で表される。 Here, if a n = βρA n , b n = βρB n , c = βρC, e = βρE, each luminance I k (k = 0, 1, 2, 3, 4, 5) is expressed by the following equation. Is done.

Figure 0005032943
Figure 0005032943

相対位相演算手段33では、IとI及びIとIのそれぞれの差分値を用いて、次式によって相対位相φの推定値<φ>を求める。 The relative phase calculation means 33 obtains an estimated value <φ> of the relative phase φ by the following equation using the difference values of I 0 and I 2 and I 1 and I 3 .

Figure 0005032943
Figure 0005032943

そして、絶対位相演算手段34では、IとI及びIとIの加算値、並びにI,Iを用いて、正弦波の振幅a,bの推定値<a>,<b>、正弦波の中心値cの推定値<c>を次式によって求める。 Then, the absolute phase calculating means 34, the sum of I 0 and I 2 and I 1 and I 3, and I 4, with I 5, the sine wave amplitude a n, the estimated value of b n <a n> , <B n >, an estimated value <c> of the center value c of the sine wave is obtained by the following equation.

Figure 0005032943
Figure 0005032943

ここで、絶対位相演算手段34では、正弦波の中心値C、及びその推定値<c>、正弦波の振幅a,bの推定値<a>,<b>を用いて、正弦波の振幅A,Bの推定値<A>,<B>を次式によって求め、表2を参照して正弦波の振幅A,Bの推定値<A>,<B>と対応する縞次数nの推定値<n>を求める。 Here, the absolute phase calculating means 34, the center value C of the sine wave, and its estimate <c>, the amplitude a n of the sine wave, the estimate of b n <a n>, using <b n>, amplitude a n of the sine wave, the estimate <A n of B n>, <the B n> calculated by the following equation, the sine wave with reference to Table 2 the amplitude a n, the estimated value of B n <A n>, An estimated value <n> of the fringe order n corresponding to <B n > is obtained.

Figure 0005032943
Figure 0005032943

更に、絶対位相演算手段34は、相対位相φの推定値<φ>と縞次数nの推定値<n>とから絶対位相Φの推定値<Φ>を上記(3)式によって求める。そして、3次元座標演算手段35において絶対位相の推定値<Φ>から三角測量の原理により各画素(u,v)での高さ情報を求めるとともに、各画素(u,v)に対応する被計測物M上の投影点の3次元空間での絶対的な座標値を求めれば、被計測物Mの3次元形状を得ることができる。   Further, the absolute phase calculation means 34 obtains the estimated value <Φ> of the absolute phase Φ from the estimated value <φ> of the relative phase φ and the estimated value <n> of the fringe order n by the above equation (3). Then, the three-dimensional coordinate calculation means 35 obtains height information at each pixel (u, v) from the absolute phase estimated value <Φ> by the principle of triangulation, and the object corresponding to each pixel (u, v). If the absolute coordinate value in the three-dimensional space of the projection point on the measurement object M is obtained, the three-dimensional shape of the measurement object M can be obtained.

上述のように、本実施形態によれば、位相シフト法を利用した3次元形状計測において必須となる正弦波状の縞パターンの各々において、周期に応じて正弦波の振幅Aを変化させた2種類(0,π/2)の投影パターン、及び周期に応じて前記2種類の投影パターンの振幅の変化とは異なる態様で正弦波の振幅Bを変化させた残りの2種類(π,3π/2)の投影パターン、並びに正弦波の中心値Cから成る均一な投影パターンを生成して被計測物Mに投影させるため、周期毎の振幅A,Bの違いから周期を推定して相対位相を位相接続できるから、特許文献2に記載されている従来例のように高価な投影装置や撮像装置を用いる必要が無く、その結果、表面に段差や孔のある物体の3次元形状をコスト上昇を抑えながら少ない撮像回数(本実施形態では5回)で計測することができる。また、振幅が互いに異なる投影パターンを組み合わせて周期を推定するので、振幅の種類が少なくても多くの周期を推定することができ、したがって小さい振幅での位相検出を回避することができ、位相の検出精度が低下するのを防ぐことができる。 As described above, according to the present embodiment, the sine wave amplitude An is changed in accordance with the period in each of the sine wave-like fringe patterns essential in the three-dimensional shape measurement using the phase shift method. The remaining two types (π, 3π) in which the amplitude B n of the sine wave is changed in a manner different from the change in amplitude of the two types of projection patterns according to the type (0, π / 2) projection pattern and the period. / 2) and a uniform projection pattern composed of the center value C of the sine wave are generated and projected onto the object M, the period is estimated from the difference between the amplitudes A n and B n for each period. Since the relative phases can be phase-connected, there is no need to use an expensive projection device or imaging device as in the conventional example described in Patent Document 2, and as a result, a three-dimensional shape of an object having a step or a hole on the surface can be obtained. Less photography while suppressing cost increase Number (in this embodiment 5 times) can be measured by. In addition, since the period is estimated by combining projection patterns having different amplitudes, it is possible to estimate many periods even if the number of types of amplitude is small, thus avoiding phase detection with a small amplitude, It can prevent that detection accuracy falls.

ところで、上記では4種類の投影パターンを用いて3次元形状の計測を行ったが、光の強度を正弦波状且つ2π/3ずつ位相をシフトして変化させた3種類(0,2π/3,4π/3)の縞パターンを用いて計測を行ってもよい。この場合、4種類の投影パターンを用いる場合と比較して撮像回数を1回減らすことができる。以下、3種類の縞パターンを用いた場合について説明する。3種類の投影パターンP(k=0,1,2)は次式で表される。 By the way, although the three-dimensional shape was measured using four types of projection patterns in the above, the three types (0, 2π / 3, 3) in which the intensity of light is changed in a sine wave shape and the phase is shifted by 2π / 3. Measurement may be performed using a 4π / 3) stripe pattern. In this case, the number of times of imaging can be reduced by one compared to the case of using four types of projection patterns. Hereinafter, a case where three types of stripe patterns are used will be described. Three types of projection patterns P k (k = 0, 1, 2) are expressed by the following equations.

Figure 0005032943
Figure 0005032943

投影パターンPが投影された状態で撮像装置2で撮像された画像上の任意の画素(u,v)における輝度(濃度値)I〜Iは、環境光の影響も含めて次式で表される。尚、Iは投影パターンPが投影されない状態で撮像装置2で撮像された画像上の任意の画素(u,v)における輝度(濃度値)を表している。 The luminances (density values) I 0 to I 3 at arbitrary pixels (u, v) on the image captured by the imaging device 2 in a state in which the projection pattern P k is projected are expressed by the following formulas including the influence of ambient light. It is represented by I 4 represents the luminance (density value) at an arbitrary pixel (u, v) on the image captured by the imaging device 2 in a state where the projection pattern P k is not projected.

Figure 0005032943
Figure 0005032943

ここで、a=βρA,b=βρB,c=βρC,e=βρEとおくと、各輝度I(k=0,1,2,3,4)は次式で表される。 Here, when a n = βρA n , b n = βρB n , c = βρC, e = βρE, each luminance I k (k = 0, 1, 2, 3, 4) is expressed by the following equation. .

Figure 0005032943
Figure 0005032943

相対位相演算手段33では、I〜Iを用いて、次式によって相対位相φの推定値<φ>と正弦波の振幅a,bの推定値<a>,<b>を求める。 Relative phase calculating means 33, using I 0 ~I 3, estimates of relative phase phi by the following equation: <phi> an estimate of the amplitude a n, b n of the sinusoidal <a n>, <b n> Ask for.

Figure 0005032943
Figure 0005032943

そして、絶対位相演算手段34では、I,Iを用いて、正弦波の中心値cの推定値<c>を次式によって求める。 Then, the absolute phase calculation means 34 uses I 3 and I 4 to obtain an estimated value <c> of the center value c of the sine wave by the following equation.

Figure 0005032943
Figure 0005032943

ここで、絶対位相演算手段34では、正弦波の中心値C、及びその推定値<c>、正弦波の振幅a,bの推定値<a>,<b>を用いて、正弦波の振幅A,Bの推定値<A>,<B>を上記(5)式、(6)式によって求め、表2を参照して正弦波の振幅A,Bの推定値<A>,<B>と対応する縞次数nの推定値<n>を求める。更に、絶対位相演算手段34は、相対位相φの推定値<φ>と縞次数nの推定値<n>とから絶対位相Φの推定値<Φ>を上記(3)式によって求める。そして、3次元座標演算手段35において絶対位相の推定値<Φ>から三角測量の原理により各画素(u,v)での高さ情報を求めるとともに、各画素(u,v)に対応する被計測物M上の投影点の3次元空間での絶対的な座標値を求めれば、被計測物Mの3次元形状を得ることができる。 Here, the absolute phase calculating means 34, the center value C of the sine wave, and its estimate <c>, the amplitude a n of the sine wave, the estimate of b n <a n>, using <b n>, amplitude a n of the sine wave, the estimate of B n <A n>, <B n> the equation (5), (6) determined by the equation, the amplitude a n of the sine wave with reference to Table 2, B n estimates <A n>, obtaining an estimate of the fringe order n corresponding to <B n><n>. Further, the absolute phase calculation means 34 obtains the estimated value <Φ> of the absolute phase Φ from the estimated value <φ> of the relative phase φ and the estimated value <n> of the fringe order n by the above equation (3). Then, the three-dimensional coordinate calculation means 35 obtains height information at each pixel (u, v) from the absolute phase estimated value <Φ> by the principle of triangulation, and the object corresponding to each pixel (u, v). If the absolute coordinate value in the three-dimensional space of the projection point on the measurement object M is obtained, the three-dimensional shape of the measurement object M can be obtained.

尚、暗室での計測等のように、環境光が無い、即ちE=0と近似できる場合には、無パターン画像取得手段32を必要とせず、上記の4種類の投影パターンを用いる場合及び3種類の投影パターンを用いる場合の何れにおいても撮像回数を1回減らすことができる。環境光が無い場合には、上記4種類の投影パターンを用いる計測においては、E=0,e=0,I=0として各計算を行い、上記3種類の投影パターンを用いる計測においては、E=0,e=0,I=0として各計算を行えばよい。 When there is no ambient light, that is, it can be approximated to E = 0, as in measurement in a dark room, the patternless image acquisition unit 32 is not required and the above four types of projection patterns are used. In any case of using different types of projection patterns, the number of times of imaging can be reduced by one. When there is no ambient light, in the measurement using the four types of projection patterns, each calculation is performed with E = 0, e = 0, and I 5 = 0. In the measurement using the three types of projection patterns, Each calculation may be performed with E = 0, e = 0, and I 4 = 0.

また、被計測物Mの表面反射率ρ、撮像装置2における光電変換係数βが既知であれば、正弦波の振幅a,bの推定値<a>,<b>が求まれば(4)式から正弦波の振幅A,Bの推定値<A>,<B>を求めることができるので、上記の4種類の投影パターンを用いる場合及び3種類の投影パターンを用いる場合の何れにおいても、正弦波の中心値cの推定値<c>を求める過程を必要とせず、したがって無パターン画像取得手段32を必要としないために、環境光が有る場合において撮像回数を1回減らすことができる。 The surface reflectance of the object to be measured M [rho, if the photoelectric conversion coefficient β is known in the image pickup apparatus 2, the amplitude a n of the sine wave, the estimate of b n <a n>, which Motomema the <b n> If (4) estimates <A n of the amplitude a n, B n of the sinusoidal from expression>, <since B n> can be obtained, if and three using four types of projection pattern of the projection pattern In any case, the process of obtaining the estimated value <c> of the center value c of the sine wave is not required, and therefore the non-pattern image acquisition means 32 is not required. Can be reduced once.

(実施形態3)
本実施形態の3次元形状計測装置は、投影パターン制御手段30が実施形態1とは異なる投影パターンを生成する点で相違しているが、装置の構成は実施形態1と共通であるので、実施形態1と共通する構成要素には同一の符号を付して説明を省略する。また、3次元形状計測方法に関しても実施形態1と共通であるので、実施形態1と共通する点については説明を省略する。
(Embodiment 3)
The three-dimensional shape measurement apparatus of the present embodiment is different in that the projection pattern control unit 30 generates a projection pattern different from that of the first embodiment, but the configuration of the apparatus is the same as that of the first embodiment. Constituent elements common to the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Further, the three-dimensional shape measurement method is also common to the first embodiment, and thus the description of the points common to the first embodiment is omitted.

本実施形態においては、光の強度を正弦波状且つ既知量であるS,Sずつ位相をシフトして変化させた3種類(0,S,S)の各々の縞パターンにおいて、前記表1に示すように1周期毎に正弦波の振幅Aを変化させた3種類の投影パターンを投影パターン制御手段30により生成し、当該投影パターンを投影装置1から被計測物Mに投影させる。 In the present embodiment, in each of the three kinds of fringe patterns (0, S 1 , S 2 ) in which the light intensity is changed by shifting the phase by a sine wave and a known amount of S 1 , S 2 , three of the projected pattern obtained by changing the amplitude a n of the sine wave in each cycle as shown in Table 1 were produced by a projection pattern control unit 30, to project the projection pattern from the projection apparatus 1 to the measured object M .

3種類の投影パターンP(k=0,1,2)並びに縞次数nは次式で表される。 Three types of projection patterns P k (k = 0, 1, 2) and fringe order n are expressed by the following equations.

Figure 0005032943
Figure 0005032943

投影パターンPが投影された状態で撮像装置2で撮像された画像上の任意の画素(u,v)における輝度(濃度値)I〜Iは、環境光の影響も含めて次式で表される。尚、Iは投影パターンPが投影されない状態で撮像装置2で撮像された画像上の任意の画素(u,v)における輝度(濃度値)を表している。 Luminances (density values) I 0 to I 2 at arbitrary pixels (u, v) on the image captured by the imaging device 2 in a state in which the projection pattern P k is projected are expressed by the following equation including the influence of ambient light. It is represented by Note that I 3 represents the luminance (density value) at an arbitrary pixel (u, v) on the image captured by the imaging device 2 in a state where the projection pattern P k is not projected.

Figure 0005032943
Figure 0005032943

ここで、a=βρA,c=βρC,e=βρEとおくと、各輝度I(k=0,1,2,3)は次式で表される。 Here, when a n = βρA n , c = βρC, and e = βρE, each luminance I k (k = 0, 1, 2, 3) is expressed by the following equation.

Figure 0005032943
Figure 0005032943

相対位相演算手段33では、I〜Iを用いて下記のように相対位相φの推定値<φ>及び正弦波の振幅aの推定値<a>を求める。先ず、次式のように上式におけるsin(Φ),cos(Φ)の各係数を揃える。 Relative phase calculating means 33 calculates an estimate of the relative phase phi as follows <phi>, and estimates <a n of the amplitude a n of the sinusoidal> using I 0 ~I 2. First, the coefficients of sin (Φ) and cos (Φ) in the above expression are aligned as in the following expression.

Figure 0005032943
Figure 0005032943

次に、上式を用いて相対位相φの推定値<φ>及び正弦波の振幅aの推定値<a>を求める。 Then, the estimated value of the relative phase phi with the above equation obtains the <phi>, and estimates <a n of the amplitude a n sinusoidal>.

Figure 0005032943
Figure 0005032943

尚、上式におけるF,G,Hは次式で表される。   Note that F, G, and H in the above equation are expressed by the following equations.

Figure 0005032943
Figure 0005032943

そして、絶対位相演算手段34では、I及びI、並びに相対位相φの推定値<φ>及び正弦波の振幅aの推定値<a>を用いて正弦波の中心値cの推定値<c>を次式によって求める。 Then, the absolute phase calculating means 34, I 0 and I 3, and estimation of the center value c of the sine wave using an estimate of the relative phase phi <phi>, and estimates <a n of the amplitude a n sinusoidal> The value <c> is obtained by the following equation.

Figure 0005032943
Figure 0005032943

ここで、絶対位相演算手段34では、正弦波の中心値C、及びその推定値<c>、正弦波の振幅aの推定値<a>を用いて、正弦波の振幅Aの推定値<A>を上記(2)式によって求め、表1を参照して正弦波の振幅Aの推定値<A>と対応する縞次数nの推定値<n>を求める。更に、絶対位相演算手段34は、相対位相φの推定値<φ>と縞次数nの推定値<n>とから絶対位相Φの推定値<Φ>を上記(3)式によって求める。そして、3次元座標演算手段35において絶対位相の推定値<Φ>から三角測量の原理により各画素(u,v)での高さ情報を求めるとともに、各画素(u,v)に対応する被計測物M上の投影点の3次元空間での絶対的な座標値を求めれば、被計測物Mの3次元形状を得ることができる。 Here, the absolute phase calculating means 34, the sine wave center value C, and the estimated value <c>, estimate of the amplitude a n sine wave using <a n>, the estimation of the amplitude A n of the sinusoidal value <A n> determined by the above equation (2), the estimated value of the fringe order n corresponding to the estimated value <A n> of the amplitude a n of the sine wave with reference to Table 1 Request <n>. Further, the absolute phase calculation means 34 obtains the estimated value <Φ> of the absolute phase Φ from the estimated value <φ> of the relative phase φ and the estimated value <n> of the fringe order n by the above equation (3). Then, the three-dimensional coordinate calculation means 35 obtains height information at each pixel (u, v) from the absolute phase estimated value <Φ> by the principle of triangulation, and the object corresponding to each pixel (u, v). If the absolute coordinate value in the three-dimensional space of the projection point on the measurement object M is obtained, the three-dimensional shape of the measurement object M can be obtained.

上述のように、本実施形態によれば、等間隔ではなく既知量S,Sずつ位相をシフトさせた複数種類の縞パターンから投影パターンを生成した場合においても、実施形態1と同様に周期毎の正弦波の振幅Aの違いから周期を推定して相対位相を位相接続できるから、特許文献2に記載されている従来例のように高価な投影装置や撮像装置を用いる必要が無く、その結果、表面に段差や孔のある物体の3次元形状をコスト上昇を抑えながら少ない撮像回数(本実施形態では4回)で計測することができる。 As described above, according to the present embodiment, even when a projection pattern is generated from a plurality of types of fringe patterns whose phases are shifted by known amounts S 1 and S 2 instead of at equal intervals, similarly to the first embodiment. because the relative phase can be phase connection by estimating the period from the difference of the amplitude a n of the sine wave of each cycle, there is no need to use an expensive projection device or an imaging device as in the conventional example described in Patent Document 2 As a result, the three-dimensional shape of an object having a step or a hole on the surface can be measured with a small number of imaging operations (four times in this embodiment) while suppressing an increase in cost.

尚、暗室での計測等のように、環境光が無い、即ちE=0と近似できる場合には、無パターン画像取得手段32を必要とせず、撮像回数を1回減らすことができる。環境光が無い場合には、E=0,e=0,I=0として各計算を行えばよい。 When there is no ambient light, such as measurement in a dark room, that is, it can be approximated to E = 0, the non-pattern image acquisition means 32 is not required, and the number of imaging can be reduced by one. When there is no ambient light, each calculation may be performed with E = 0, e = 0, and I 3 = 0.

また、被計測物Mの表面反射率ρ、撮像装置2における光電変換係数βが既知であれば、正弦波の振幅aの推定値<a>が求まれば(1)式から正弦波の振幅Aの推定値<A>を求めることができるので、正弦波の中心値cの推定値<c>を求める過程を必要とせず、したがって無パターン画像取得手段32を必要としないために、環境光が有る場合において撮像回数を1回減らすことができる。 The surface reflectance of the object to be measured M [rho, sine wave from long photoelectric conversion coefficient β is known in the imaging apparatus 2, if the estimated value of the amplitude a n sine wave <a n> Motomare (1) it is possible to in seeking amplitude a estimated value of n <A n>, without the need of a process of obtaining an estimate of the central value c of the sine wave <c>, therefore does not require a no-pattern image acquiring means 32 In addition, when there is ambient light, the number of imaging can be reduced by one.

本発明に係る3次元形状計測装置の実施形態を示すブロック図である。It is a block diagram which shows embodiment of the three-dimensional shape measuring apparatus which concerns on this invention. (a)〜(d)は実施形態1における投影パターンの波形図である。(A)-(d) is a wave form diagram of the projection pattern in Embodiment 1. FIG. (a)〜(e)は実施形態2における投影パターンの波形図である。(A)-(e) is a wave form diagram of the projection pattern in Embodiment 2. FIG.

符号の説明Explanation of symbols

1 投影装置
2 撮像装置
3 画像処理装置
30 投影パターン制御手段
31 画像取得手段
32 無パターン画像取得手段
33 相対位相演算手段
34 絶対位相演算手段
35 3次元座標演算手段
M 被計測物
DESCRIPTION OF SYMBOLS 1 Projection apparatus 2 Imaging apparatus 3 Image processing apparatus 30 Projection pattern control means 31 Image acquisition means 32 Unpatterned image acquisition means 33 Relative phase calculation means 34 Absolute phase calculation means 35 Three-dimensional coordinate calculation means M Measurement object

Claims (8)

被計測物に任意パターンの光を投影する投影手段と、投影手段を制御して所定の光パターンから成る投影パターンを被計測物に投影させる投影パターン制御手段と、被計測物を撮像する撮像手段と、撮像手段の撮像画像から投影パターンが投影された被計測物の濃淡画像を取得する画像取得手段と、画像取得手段で取得した濃淡画像内の任意の位置における投影パターンの相対位相を演算する相対位相演算手段と、任意位置の相対位相を位相接続して投影パターンの絶対位相を演算する絶対位相演算手段と、絶対位相から被計測物の3次元座標を演算する3次元座標演算手段とを備え、投影パターン制御手段は、光の強度を正弦波状且つ既知量位相をシフトして変化させた複数種類の縞パターンにおいて各々の振幅を1周期毎に変化させた投影パターンを生成して投影手段より被計測物に投影させ、相対位相演算手段は、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて相対位相を演算し、絶対位相演算手段は、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて投影パターンの振幅を演算するとともに、当該振幅から周期を推定し、相対位相を位相接続して絶対位相を演算することを特徴とする3次元形状計測装置。   Projection means for projecting an arbitrary pattern of light onto the measurement object, projection pattern control means for controlling the projection means to project a projection pattern composed of a predetermined light pattern onto the measurement object, and imaging means for imaging the measurement object And an image acquisition unit that acquires a grayscale image of a measurement object on which a projection pattern is projected from a captured image of the imaging unit, and a relative phase of the projection pattern at an arbitrary position in the grayscale image acquired by the image acquisition unit Relative phase calculation means, absolute phase calculation means for calculating the absolute phase of the projection pattern by connecting the relative phases at arbitrary positions, and three-dimensional coordinate calculation means for calculating the three-dimensional coordinates of the measurement object from the absolute phase The projection pattern control means includes a plurality of types of fringe patterns in which the light intensity is changed by changing the phase of a sine wave and a known amount of phase, and the amplitude is changed for each cycle. A pattern is generated and projected from the projection means onto the measurement object, and the relative phase calculation means calculates the relative phase based on the density value in the grayscale image of the measurement object projected by projecting the projection pattern, and the absolute phase The computing means computes the amplitude of the projection pattern based on the density value in the grayscale image of the object measured by projecting the projection pattern, estimates the period from the amplitude, and connects the relative phases in phase A three-dimensional shape measuring apparatus characterized by calculating a phase. 被計測物に任意パターンの光を投影する投影手段と、投影手段を制御して所定の光パターンから成る投影パターンを被計測物に投影させる投影パターン制御手段と、被計測物を撮像する撮像手段と、撮像手段の撮像画像から投影パターンが投影された被計測物の濃淡画像を取得する画像取得手段と、画像取得手段で取得した濃淡画像内の任意の位置における投影パターンの相対位相を演算する相対位相演算手段と、任意位置の相対位相を位相接続して投影パターンの絶対位相を演算する絶対位相演算手段と、絶対位相から被計測物の3次元座標を演算する3次元座標演算手段とを備え、投影パターン制御手段は、光の強度を正弦波状且つ既知量位相をシフトして変化させた複数種類の縞パターンのうち、少なくとも1種類以上の縞パターンにおいて振幅を周期に応じて変化させた投影パターンと、残りの縞パターンにおいて振幅を周期に応じて前記投影パターンとは異なる態様で変化させた投影パターンと、縞パターンの振幅中心値から成る均一な投影パターンとを生成して投影手段より被計測物に投影させ、相対位相演算手段は、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて相対位相を演算し、絶対位相演算手段は、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて投影パターンの振幅を演算するとともに、当該振幅から周期を推定し、相対位相を位相接続して絶対位相を演算することを特徴とする3次元形状計測装置。   Projection means for projecting an arbitrary pattern of light onto the measurement object, projection pattern control means for controlling the projection means to project a projection pattern composed of a predetermined light pattern onto the measurement object, and imaging means for imaging the measurement object And an image acquisition unit that acquires a grayscale image of a measurement object on which a projection pattern is projected from a captured image of the imaging unit, and a relative phase of the projection pattern at an arbitrary position in the grayscale image acquired by the image acquisition unit Relative phase calculation means, absolute phase calculation means for calculating the absolute phase of the projection pattern by connecting the relative phases at arbitrary positions, and three-dimensional coordinate calculation means for calculating the three-dimensional coordinates of the measurement object from the absolute phase Provided, and the projection pattern control means applies at least one kind of fringe pattern among the plural kinds of fringe patterns in which the intensity of light is changed by shifting the phase of the sine wave and the known amount. The projection pattern in which the amplitude is changed according to the period, the projection pattern in which the amplitude is changed in the aspect different from the projection pattern according to the period in the remaining stripe pattern, and the uniform center value of the stripe pattern A projection pattern is generated and projected onto the measurement object from the projection means, and the relative phase calculation means calculates the relative phase based on the density value in the grayscale image of the measurement object that is imaged by projecting the projection pattern, The absolute phase calculation means calculates the amplitude of the projection pattern based on the density value in the grayscale image of the object to be measured that is imaged by projecting the projection pattern, estimates the period from the amplitude, and phase-connects the relative phases. A three-dimensional shape measuring apparatus characterized by calculating an absolute phase. 前記画像取得手段は、撮像手段の撮像画像から投影パターンが投影されていない状態の被計測物の濃淡画像を取得する無パターン画像取得手段を備えたことを特徴とする請求項1又は2記載の3次元形状計測装置。   The said image acquisition means is equipped with the non-pattern image acquisition means which acquires the grayscale image of the to-be-measured object in the state in which the projection pattern is not projected from the captured image of an imaging means. 3D shape measuring device. 前記投影パターン制御手段は、光の強度を正弦波状且つ等間隔に位相をシフトして変化させた複数種類の縞パターンから投影パターンを生成することを特徴とする請求項1乃至3の何れか1項に記載の3次元形状計測装置。   4. The projection pattern control unit according to claim 1, wherein the projection pattern control unit generates a projection pattern from a plurality of types of fringe patterns in which the intensity of light is changed by shifting the phase in a sine wave shape and at equal intervals. The three-dimensional shape measuring apparatus according to item. 所定の光パターンから成る投影パターンを被計測物に投影し、投影パターンを投影した被計測物の濃淡画像を取得し、投影パターンを投影したときの濃淡画像内の任意の位置における投影パターンの相対位相を演算し、任意位置の相対位相を位相接続して投影パターンの絶対位相を演算し、絶対位相から被計測物の3次元座標を演算することで被計測物の3次元形状を計測する3次元形状計測方法であって、光の強度を正弦波状且つ既知量位相をシフトして変化させた複数種類の縞パターンにおいて各々の振幅を1周期毎に変化させた投影パターンを生成して被計測物に投影する過程と、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて相対位相を演算する過程と、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて投影パターンの振幅を演算するとともに、当該振幅から周期を推定し、相対位相を位相接続して絶対位相を演算する過程とを有することを特徴とする3次元形状計測方法。   Projecting a projection pattern consisting of a predetermined light pattern onto an object to be measured, obtaining a grayscale image of the object to be measured on which the projection pattern is projected, and relative to the projection pattern at an arbitrary position in the grayscale image when the projection pattern is projected The phase is calculated, the relative phase of the arbitrary position is connected in phase, the absolute phase of the projection pattern is calculated, and the three-dimensional coordinates of the measurement object are calculated from the absolute phase 3 Dimensional shape measurement method that generates a projection pattern in which each amplitude is changed for each period in a plurality of types of fringe patterns in which the intensity of light is changed sinusoidally and the phase is shifted by a known amount. The process of projecting onto the object, the process of calculating the relative phase based on the density value in the grayscale image of the object to be measured that is projected by projecting the projection pattern, and the object to be measured that is imaged by projecting the projection pattern A three-dimensional shape comprising: calculating an amplitude of a projection pattern based on a density value in a grayscale image, estimating a period from the amplitude, and calculating an absolute phase by phase-connecting relative phases. Measurement method. 所定の光パターンから成る投影パターンを被計測物に投影し、投影パターンを投影した被計測物の濃淡画像を取得し、投影パターンを投影したときの濃淡画像内の任意の位置における投影パターンの相対位相を演算し、任意位置の相対位相を位相接続して投影パターンの絶対位相を演算し、絶対位相から被計測物の3次元座標を演算することで被計測物の3次元形状を計測する3次元形状計測方法であって、光の強度を正弦波状且つ既知量位相をシフトして変化させた複数種類の縞パターンのうち、少なくとも1種類以上の縞パターンにおいて振幅を周期に応じて変化させた投影パターンと、残りの縞パターンにおいて振幅を周期に応じて前記投影パターンとは異なる態様で変化させた投影パターンと、縞パターンの振幅中心値から成る均一な投影パターンとを生成して被計測物に投影する過程と、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて相対位相を演算する過程と、投影パターンを投影して撮像された被計測物の濃淡画像における濃度値に基づいて投影パターンの振幅を演算するとともに、当該振幅から周期を推定し、相対位相を位相接続して絶対位相を演算する過程とを有することを特徴とする3次元形状計測方法。   Projecting a projection pattern consisting of a predetermined light pattern onto an object to be measured, obtaining a grayscale image of the object to be measured on which the projection pattern is projected, and relative to the projection pattern at an arbitrary position in the grayscale image when the projection pattern is projected The phase is calculated, the relative phase of the arbitrary position is connected in phase, the absolute phase of the projection pattern is calculated, and the three-dimensional coordinates of the measurement object are calculated from the absolute phase 3 This is a three-dimensional shape measurement method, and the amplitude is changed in accordance with the period in at least one or more stripe patterns among a plurality of types of stripe patterns in which the intensity of light is changed sinusoidally and the phase is shifted by a known amount. Uniform comprising the projection pattern, the projection pattern in which the amplitude of the remaining stripe pattern is changed in a manner different from the projection pattern according to the period, and the amplitude center value of the stripe pattern The process of generating a projection pattern and projecting it onto the object to be measured, the process of calculating the relative phase based on the density value in the grayscale image of the object measured by projecting the projection pattern, and projecting the projection pattern And calculating the amplitude of the projection pattern based on the density value in the grayscale image of the object to be measured, estimating the period from the amplitude, and calculating the absolute phase by connecting the relative phases in phase. A three-dimensional shape measuring method characterized by 前記投影パターンを投影した被計測物の濃淡画像を取得する過程において、投影パターンを投影していない状態の被計測物の濃淡画像を取得する過程を有することを特徴とする請求項5又は6記載の3次元形状計測方法。   7. The process of acquiring a grayscale image of a measurement object on which the projection pattern is projected, and acquiring a grayscale image of the measurement object in a state where no projection pattern is projected. 3D shape measurement method. 前記投影パターン制御手段は、光の強度を正弦波状且つ等間隔に位相をシフトして変化させた複数種類の縞パターンから投影パターンを生成することを特徴とする請求項5乃至7の何れか1項に記載の3次元形状計測方法。   The projection pattern control means generates a projection pattern from a plurality of types of fringe patterns in which the intensity of light is changed by shifting the phase in a sine wave shape and at equal intervals. The three-dimensional shape measuring method according to item.
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