JP2006023083A - Infrared laser measurement/image-display method, and device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an infrared measurement/image-display method capable of measuring an Indian-ink painting or calligraphy not observable by the naked eyes because of a stain or the like on a surface, without heating a measured object, and allowing observation as a distortion-free image, and a device therefor. <P>SOLUTION: This infrared measurement/image-display device has a semiconductor laser 1 for oscillating a fixed wavelength of infrared pulse laser, a projection mirror 2 for emitting the infrared pulse laser toward the measured object 110, a motor-driven mirror scanning mechanism 3 and a motor-driven head scanning mechanism 4 for scanning the projection mirror 2 at a fixed pitch, a photoreception lens 5 for receiving reflected beam from the measured object 110, a CCD line sensor 6 for converting the beam from the photoreception lens 5 into an electric signal, an A/D converter 7 for converting the signal from the CCD line sensor 6, a signal processing electronic circuit 8 for calculating three-dimensional coordinates and intensity of the reflected beam in a point where a laser beam is reflected, and an image display 9 for displaying a signal from the signal processing electronic circuit 8 as a three-dimensional image. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a novel infrared laser measurement / image display method and apparatus for observing a blackboard or blackboard that cannot be seen with the naked eye due to surface dirt as a three-dimensional image.

  In general, an infrared camera is used for observing ink brush paintings and ink paintings that are difficult to see because the surface is dirty. Infrared rays having a long wavelength have a greater transmission power than visible light, and therefore penetrate through a dirty surface layer to reach the inside. Also, the ink has a lower light reflectance than the base wood or paper, and the intensity of the reflected light differs between the ink and other parts. Based on this principle, if an infrared camera is used, it is possible to see pictures and characters that cannot be observed with the naked eye due to surface dirt.

  However, when an infrared camera is used, a large amount of infrared rays are irradiated using a projector, so that there is a concern that the material deteriorates due to heating. In general, the maximum size that can be shot at one time is about 300 mm x 300 mm. If the size is larger, it is necessary to take several images. Image unevenness due to non-uniformity becomes a problem.

  In response to the above problems, the “infrared image scanner” disclosed in Non-Patent Document 1 uses a flatbed image scanner, and irradiates the material with the minimum necessary infrared rays during observation, and the object to be measured A system that receives the reflected light from a CCD linear image sensor is shown.

  There is a three-dimensional laser scanner as a system that measures a large size or a shape of a non-flat plate without distortion. This is a method of scanning a laser to measure the three-dimensional shape of an object to be measured. As disclosed in Non-Patent Document 2, it is used to measure an indefinite shape such as a copper spear. The measurement distance varies depending on the model, and there are various types ranging from about 10 cm to several hundred meters. Lasers used in this system range from visible light to near infrared rays, and have a wavelength in the range of 0.5 to 0.9 μm.

Kenji Miyahara, et al., Japan Society for Cultural Property Science, 17th Annual Meeting Abstract, p.204 (2000) Toshio Tsukamoto, et al., Japan Society for Cultural Properties Science, 17th Annual Meeting Abstract, p.208 (2000)

It would be extremely useful in the field of research and preservation of cultural properties if it was possible to see inscriptions and sumi-e that could not be observed with the naked eye due to dirt on the surface, but the conventional techniques have the following problems.
(1) When observing an irregularly shaped earthenware or a thing drawn on a large ceiling, the resulting image is distorted and image unevenness is caused by unevenness of the light projection conditions, making it difficult to obtain a clear image. .
(2) Infrared irradiation by a projector having a width in wavelength requires long-time irradiation, and there is a concern of deterioration of materials due to long-time irradiation.

  A problem with the prior art is that the infrared wavelength used to illuminate the material using the projector has a wide range. Its width is approximately 0.8 to 2.0 μm. On the other hand, the infrared camera for detecting reflected light has a width of 0.8 to 1 μm for an infrared film and 0.8 to 2 μm for an infrared vidicon camera. In general, the longer the wavelength, the thicker the surface layer that can be transmitted. Therefore, when the surface layer is thick, only the long-wavelength infrared rays detect the ground, and the short-wavelength infrared rays are useless. As a result, unnecessary information is superimposed on the obtained image and lacks clarity. Further, in order to obtain more background information, it is necessary to irradiate a large amount of infrared rays including unnecessary wavelengths, which results in further heating the material.

  Furthermore, the system of Non-Patent Document 1 avoids a large amount of infrared irradiation and can obtain an image with little distortion, but can handle only a flat plate or paper-like one, and is curved such as earthenware. It is difficult to observe the surface. Also, objects drawn on fixed objects such as ceilings and walls cannot be measured.

  In the system of Non-Patent Document 2, the shape can be recorded without distortion. However, since the wavelength is short, when the thickness of the surface layer is 0.1 mm or more, the light does not transmit to the ground, It is difficult to observe sumi-e.

  An object of the present invention is an infrared laser measurement / image display that can measure a black-and-white painting or ink-print that cannot be observed with the naked eye due to surface dirt, etc. without heating the object to be measured, and can be viewed as an image without distortion. It is to provide a method and apparatus thereof.

  The present invention includes a step of irradiating an object to be measured with a pulsed spot infrared laser at a constant pitch, a step of detecting the intensity of reflected light at each position of the irradiation section, and a plurality of locations for the low intensity portion. A step of selecting and obtaining a maximum value among them, a step of replacing all points where the intensity greater than the maximum value is measured with the maximum intensity, and a step of displaying as an image based on the maximum intensity and other intensities And an infrared laser measurement / image display method.

  Displaying the maximum intensity and the other intensity as images of different colors, outputting the detected intensity corresponding to the three-dimensional coordinates of the object to be measured, and the low intensity part The black portion of the object to be measured is preferably used.

  That is, in the infrared laser measurement / image display method of the present invention, a spot-like infrared laser with a constant wavelength is pulsed onto a measurement object at a constant pitch, and the reflected light is received, so that each position where the laser hits is received. The three-dimensional coordinates and the intensity of the reflected light are detected, the intensity is converted into a color, and then output as an intensity image arranged at each coordinate position.

  The wavelength of the infrared laser is preferably a semiconductor laser that oscillates an infrared pulse laser with a constant wavelength selected from the range of 1.0 to 2.0 μm, and the thickness of the surface layer that can be transmitted due to the short wavelength is drastically reduced. The lower limit is preferably 1.0 μm or more, and the upper limit of 2.0 μm or less, which is the upper limit for reducing the thickness of the surface layer that can be transmitted due to a decrease in light energy. In addition, the range of 1.5-2.0 micrometers whose transmission capability is high is especially preferable.

Furthermore, in order to obtain an image without distortion and unevenness, it is preferable to satisfy the following requirements.
(1) Do not use an infrared projector.
(2) The absolute dimensions (three-dimensional coordinates) can be measured.
A method that satisfies these two requirements is a three-dimensional laser scanner using an infrared semiconductor laser. By scanning a pulse laser with a constant wavelength, heating of the material can be avoided and the infrared irradiation conditions can be kept constant. As a result, the requirement (1) is satisfied, the absolute coordinates can be measured by using the measurement principle of the three-dimensional laser scanner, and the requirement (2) can be satisfied. The three-dimensional coordinate measurement principle includes the time-of-flight method and the triangulation method. Considering that the size of the object to be measured is approximately 2m x 2m or less, the measurement accuracy is improved by the triangulation method. It is done. In order to improve detection capability and accuracy, it is desirable that the laser output is 10 to 50 mW, the spot diameter is 2 mm or less, and the measurement pitch is 2 mm or less.

  Infrared rays pass through the surface layer such as dirt and reach the ground, but the reflectance is small at the black portion. Therefore, the intensity of the reflected light is smaller at the black portion than at the others. However, looking at this phenomenon in more detail, the reflection of light depends on the thickness of the ink and the surface layer. Usually, since the thickness of the surface layer is not uniform, the strength varies depending on the location. When the black portion is recognized by an image and this intensity difference is converted into a color as it is and displayed, it causes image unevenness. Therefore, based on the point group (three-dimensional coordinates and a set of points having intensity) obtained by measurement, the intensity is converted into color and then output as an intensity image corresponding to each coordinate position for each color. To do. Next, the measured object and the intensity image are compared to select a plurality of black points, and the intensity is read. Next, the maximum value of the read intensity is obtained, and the intensity greater than this value is replaced with the maximum intensity of all points measured. By this process, the black portion can be clearly indicated. The black portion has different intensities depending on the thickness of the black, but this is important for recognizing the thickness and is left as it is. By displaying an image of the point group that has been subjected to this processing, it is possible to observe a sumi-e or a sumi-e.

  Further, the present invention relates to a semiconductor laser that irradiates an object to be measured with a spot-like infrared laser, a scanning device for the semiconductor laser, a light receiving device that detects the intensity of reflected light after irradiation, and the low-intensity portion. A signal processing device that selects a plurality of locations and replaces all points with an intensity greater than the maximum value of the intensity with the maximum intensity, and an image display device that displays the screen based on the maximum intensity and the other intensity. It is in the characteristic infrared laser measurement / image display device.

  The scanning device includes a light projecting mirror for irradiating the object to be measured with the laser, a mirror scanning mechanism for scanning the light projecting mirror left and right, and a motor-driven head scanning mechanism for scanning up and down, and the light receiving device includes the light receiving device. A light receiving lens that receives reflected light from the object to be measured, a CCD line sensor that converts light from the light receiving lens into an electrical signal, and an A / D converter that converts an analog signal from the sensor into a digital signal, The signal processing apparatus includes a circuit unit that outputs and calculates the intensity of the reflected light in correspondence with the three-dimensional coordinates measured based on the triangulation principle, and the image display apparatus that displays the image using the three-dimensional coordinates. Moreover, it has a power supply part and a connection cable.

  According to the present invention, an infrared laser measurement / image display that can measure a black-and-white painting or a blackboard that cannot be observed with the naked eye due to surface dirt or the like without heating the object to be measured and can be viewed as an undistorted image. A method and apparatus thereof can be provided.

  FIG. 1 is an overall configuration diagram of an infrared laser measurement / image display apparatus according to the present invention, and FIG. 2 is a detailed configuration diagram thereof. As shown in FIG. 1, the infrared laser measurement / image display apparatus according to the present embodiment includes an infrared pulse laser beam irradiation unit 22 that irradiates a measurement object 110 with an infrared pulse laser beam and a light receiving unit 21 that detects the reflected light. It is composed of an infrared laser head 101, a controller 102, and an image display device 9, and can measure without being heated, such as a black-and-white drawing or ink-print that cannot be observed with the naked eye, which will be described later, due to surface dirt, etc. It can be seen as an image without any.

  As shown in FIG. 2, the infrared laser measurement / image display device of the present invention includes a semiconductor laser 1 that oscillates an infrared pulse laser having a constant wavelength selected from a wavelength range of 1.0 to 2.0 μm, and a semiconductor laser 1. A projection mirror 2 that irradiates the object 110 with an infrared pulse laser oscillated from the motor, a motor-driven mirror scanning mechanism 3 that scans the projection mirror 2 at a constant pitch, a motor-driven head scanning mechanism 4, and The light receiving lens 5 that receives the reflected light from the measurement object 110, the CCD line sensor 6 that is a charged coupled device that converts the light from the light receiving lens 5 into an electrical signal, and the analog from the CCD line sensor 6. A / D converter 7 that converts the signal into a digital signal and the three-dimensional coordinates of the point where the laser beam is reflected based on the triangulation principle A signal processing electronic circuit unit 8 for calculating the intensity of reflected light, an image display device 9 for displaying a signal from the signal processing electronic circuit unit 8 in a three-dimensional image, a power supply unit and a connection cable (not shown). Have.

  First, the infrared laser head 101 oscillates an infrared pulse laser 18 from the infrared semiconductor laser 1 via an APC (Automatic Power Control) circuit (light output stabilization circuit) 14 in accordance with a signal from the CPU 17. The oscillated infrared pulse laser 18 irradiates the measurement object 110 via the projection mirror 2. The infrared pulse laser 18 is measured at a constant pitch by the projection mirror motor drive 15 and the projection mirror 2 rotated by the motor 12, and the infrared laser head 101 driven by the head motor drive 16 and the motor 13. Is scanned from side to side and up and down and irradiated to the whole. The projection mirror motor drive 15 and the head motor drive 16 are controlled by the CPU 17. The reflected light from the object to be measured 110 is received by the light receiving lens 5 provided in the light receiving unit 21, and the optical signal enters the signal processing electronic circuit unit 8 through the CCD line sensor 6 and the A / D converter 7. In the signal processing electronic circuit unit 8, along with the intensity of the reflected light, the three-dimensional coordinates of the points constituting the object to be measured 110 are triangular based on the projection angle, the reception angle, and the distance between the projection mirror 2 and the reception lens 5. Calculation is performed based on the surveying principle, image processing is performed based on the point cloud obtained by the measurement, and the processed image signal is sent to the image display device 9. The distance between the projection mirror 2 and the light receiving lens 5 is 100 to 150 mm, and the effective measurement range is 3 m or less. The viewing angle is ± 45 ° or more in the vertical direction and ± 45 ° or more in the horizontal direction.

  FIG. 3 is a flowchart showing a procedure for performing image processing by the signal processing electronic circuit unit on a blackboard or black book that cannot be observed with the naked eye due to dirt on the surface of the object to be measured. First, in step S100, the magnitude of intensity is converted into a color based on a point group (a set of points having three-dimensional coordinates and intensity) obtained by measurement. In step S101, the intensity image arranged at each three-dimensional coordinate is output to the image display device 9. In step S102, the measurement object 110 and the intensity image are compared to select a plurality of low-intensity portions of the black portion, and the intensity is read. In step S103, the maximum value of the read intensity is obtained. In step S104, the maximum intensity is replaced with respect to all points where the intensity greater than this value is measured. Finally, the intensity image is output to the image display device 9 in step S105.

  The black portion can be clearly indicated by the above processing. The black portion has different intensities depending on the thickness of the black, but this is important for recognizing the thickness and is left as it is. By displaying an image of the point group that has been subjected to this processing, it is possible to observe a sumi-e or a sumi-e. It is desirable that the intensity is converted to a gray scale of 256 gradations and displayed as an image.

  FIG. 4 is a diagram showing a sumi-e or ink book where the surface of the object to be measured is dirty and the background is difficult to see, and FIG. 5 is an image displayed using the infrared laser measurement / image display system of the present invention. In FIG. 4, a sumi-e or ink brush 19 of the measurement object 110 and a portion 20 having a higher strength are shown. As shown in FIG. 5, the maximum intensity is replaced for all points where the intensity greater than the maximum intensity value of the above-described sumi-e or ink-print portion in step S104 is set. The image is displayed on the image display device 9 based on the intensity. Further, since the image of FIG. 5 is displayed based on the three-dimensional coordinates, there is no distortion at all. In addition, a clear image can be obtained regardless of the thickness of the surface contamination layer by using infrared rays having a long wavelength and a constant wavelength in the range of 1.0 to 2.0 μm. Further, by adjusting the laser output, the difference between the black ink and other parts can be clearly displayed.

  As described above, according to the present embodiment, it is possible to measure a sumi-e picture or ink book that cannot be observed with the naked eye due to surface dirt or the like without heating the material, and can be viewed as an image without distortion. In particular, even if the material is large and not flat, it can be displayed on the screen as a three-dimensional image faithfully to the original shape.

  Furthermore, according to the present embodiment, the protection of cultural properties is particularly effective for sumi-e paintings on ceilings and walls of shrines, Buddhist temples, etc., investigation of characters, decoding of earthenware and wooden letters, and appraisal of drafts of paintings.

1 is an overall configuration diagram of an infrared laser measurement / image display apparatus according to the present invention. It is a whole block diagram which shows the detail of the infrared laser measurement and image display apparatus of this invention. It is a flowchart which shows the processing method in the signal processing circuit part of the infrared laser measurement and image display apparatus of this invention. It is a figure which shows the sumi-e picture and sumi-style book where the surface of a to-be-measured object is dirty and a base is hard to see. It is an image which shows the result of having measured and image-processing the sumi-e and the ink brush by the infrared laser measurement and image display apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser, 2 ... Projection mirror, 3 ... Motor drive type mirror scanning mechanism, 4 ... Motor drive type head scanning mechanism, 5 ... Light receiving lens, 6 ... CCD line sensor, 7 ... A / D converter, 8 ... Signal Processing electronic circuit unit, 9 ... image display device, 10 ... power supply unit, 11 ... connection cable, 12, 13 ... motor, 14 ... APC circuit, 15 ... light emitting mirror motor drive, 16 ... head motor drive, 17 ... CPU, 18 ... Infrared pulse laser, 19 ... Sumi-e and Sumisho, 20 ... Higher intensity than Sumi-e and Sumisho, 21 ... Light receiving part, 22 ... Infrared pulse laser light irradiation part, 100 ... Infrared laser measurement / image display system, 101 ... infrared laser head, 102 ... controller, 110 ... measurement object.

Claims (4)

  A step of irradiating the object to be measured with a spot-shaped infrared laser at a constant pitch, a step of detecting the intensity of reflected light at each position of the irradiation unit, and selecting a plurality of locations for the low intensity portion A step of obtaining a maximum value, a step of replacing all the points where the intensity greater than the maximum value is measured with a maximum intensity, and a step of displaying as an image based on the maximum intensity and the other intensity Infrared laser measurement and image display method characterized by   A semiconductor laser that irradiates the object to be measured with a spot-like infrared laser, a scanning device for the semiconductor laser, a light-receiving device that detects the intensity of reflected light after irradiation, and a plurality of locations for the low-intensity part. Infrared laser measurement, comprising: a signal processing device that replaces all points having an intensity greater than the maximum value of the intensity with a maximum intensity; and an image display device that displays a screen based on the maximum intensity and the other intensity. -Image display device.   The scanning device according to claim 2, comprising a projection mirror that irradiates the object to be measured with the laser, a mirror scanning mechanism that scans the projection mirror left and right, and a motor-driven head scanning mechanism that scans up and down. A light receiving lens that receives reflected light from the object to be measured, a CCD line sensor that converts light from the light receiving lens into an electrical signal, and an A / D converter that converts an analog signal from the sensor into a digital signal And the signal processing device includes a circuit unit that outputs and calculates the intensity of the reflected light corresponding to the three-dimensional coordinates measured based on the triangulation principle, and displays the image as an image based on the three-dimensional coordinates. An infrared laser measurement / image display device characterized by comprising the device. 4. The infrared laser measurement / image display device according to claim 2, wherein the semiconductor laser is an infrared pulse laser having a constant wavelength selected from a range of 1.0 to 2.0 [mu] m.

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