WO2008044096A1 - Procédé permettant un balayage de lumière à structure tridimensionnelle d'objets brillants ou spéculaires - Google Patents

Procédé permettant un balayage de lumière à structure tridimensionnelle d'objets brillants ou spéculaires Download PDF

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Publication number
WO2008044096A1
WO2008044096A1 PCT/IB2006/053772 IB2006053772W WO2008044096A1 WO 2008044096 A1 WO2008044096 A1 WO 2008044096A1 IB 2006053772 W IB2006053772 W IB 2006053772W WO 2008044096 A1 WO2008044096 A1 WO 2008044096A1
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WO
WIPO (PCT)
Prior art keywords
color
scanning
light source
camera
stripe
Prior art date
Application number
PCT/IB2006/053772
Other languages
English (en)
Inventor
Cem ÜNSALAN
Rifat Benveniste
Original Assignee
Yeditepe Üniversitesi
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Yeditepe Üniversitesi filed Critical Yeditepe Üniversitesi
Priority to PCT/IB2006/053772 priority Critical patent/WO2008044096A1/fr
Publication of WO2008044096A1 publication Critical patent/WO2008044096A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G01B11/25—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures by projecting a pattern, e.g. one or more lines, moiré fringes on the object
    • G01B11/2509—Color coding
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/50—Depth or shape recovery
    • G06T7/521—Depth or shape recovery from laser ranging, e.g. using interferometry; from the projection of structured light

Definitions

  • the present invention relates generally to a three-dimensional (3D) measurement system and method.
  • the invention specifically concerns the 3D measurement and shape extraction of shiny or specular objects using a laser and/or line stripe projection based scanner systems.
  • 3D scanners are devices used to extract the surface coordinates of physical objects. 3D scanners are used in various areas such as reverse engineering, computer graphics applications, cultural heritage or archeological finding scanning and medical imaging.
  • 3D scanners There are various methods used to construct 3D scanners. Two main categories of 3D scanners are 1 -) non-contact and 2-) contact. 3D scanners based on touch sensors can be counted as contact scanners. These devices are slow and do not have general usability since some objects may not be touched either due to object properties or due to their positions. Non-contact scanners can also be divided into two basic categories: 1 -) triangulation based structured light and 2-) other optical property based. Triangulation based structured light non-contact scanners are based on different methods such as: laser line based, projection line based and patterned structured light based. Patterned structured light based scanners use different pattern codification strategies such as coding by color and line width.
  • the basic working principle of triangulation based structured light 3D scanners can be described as follows; wherein a monochromatic or multi spectral light pattern such as laser lines, white or colored stripes are projected from a light source on to the physical object. The projected light is then reflected and one or more cameras acquire images of projection. The light pattern is detected from the acquired image and then the shape information is derived from the triangulation. When the stripes are moved along the object surface, the 3D computer model of the physical object is obtained.
  • a problem with structured light 3D scanning is that the properties of the surface and the lighting conditions of the medium affects the quality of the image acquired. As a result in some conditions the scanner can not be used.
  • One such problem occurs when scanning physical objects with shiny or specular surfaces. Projected structured light stripes create noise on the image acquired due to specularity of the physical object. This problem is mentioned in the archeological scanning project by Gabriele Guidi, Angelo Beraldin, and Carlo Atzeni "High-accuracy 3-D modeling of cultural heritage: The digitizing of
  • the present invention provides a method and a system to extract the shape information of the shiny or specular 3D objects with a laser or projector line stripe using image processing tools.
  • Image processing tools reduce the diffraction effects of laser or projector line stripes when projected on shiny or specular objects.
  • the vision system of the present invention generally comprises a line laser or a projector forming a line stripe, a color camera, and a computer.
  • the system is initially calibrated using the well-known triangulation techniques and the known setup of the said scanner system.
  • the said line laser or the projector line stripe is projected on the real object either using an LCD projector or a computer controlled position changing line laser.
  • the laser or projector line stripe can be of any color.
  • the color camera generates the two dimensional color image of the line laser or the projected line stripe on the 3D object.
  • the said line laser or the projected line stripe takes the shape of the projected object. Due to the shape irregularity and the specular characteristics of the said shiny object, the said laser line or the projected line laser diffracts on the said object.
  • the said computer processes the color image of the said projected line stripe or the said laser line on the 3D object. Using color invariants extracted from the said color image, the diffraction on the said object is eliminated. The said computer processes the said color invariants to extract the geometric shape information of the said shiny or specular object.
  • color invariants may be applied according to the image and object's color conditions.
  • One such color invariant, used for the structured light scanner system claimed here is specified below.
  • colorbandi and colorband 2 are the corresponding color bands of the acquired image used in the system.
  • This invariant uses the two color bands, such as the red and green bands, of the image. It takes the ratio of the difference of the color bands to their sum. As a result of this invariant, the diffractions and the specularity occurring on the object are eliminated.
  • Figure 1 illustrates the scanning system configuration schematically.
  • Figure 2 shows a flowchart of scanning process and shows the steps that the color invariants are extracted.
  • Figure 3 illustrates the separation of the color bands and how the invariants are is obtained for each pixel.
  • Figure also illustrates the resulting pixels after threshold.
  • 301 -302 illustrates the pixels taken from the red and the green bands respectively.
  • 303 illustrate the resulting pixel from the invariant.
  • the pixel after threshold is illustrated in 304.
  • the structured light 3D scanner system comprises at least a light source (101 ); a light source motion mechanism (105) which is used to move the light source (101 ) relative to the object (107); at least a camera (102) and a camera motion mechanism (106) which is used to move the camera relative to the object (107); a motion mechanism (104) for the object (107) in order to scan from different angles; a computer (103) controlling the light source (101 ), the camera (102) and the motion mechanisms (104, 105, 106) and running an image processing software therein.
  • the motion mechanisms (104, 105, 106) can move and/or rotate in any direction.
  • the computer (103) can be any kind of electronical controller, and said camera (102) must be a color camera in order to process the color invariants.
  • the invention is a structured light 3D scanner using color invariants to process and obtain the shape and depth information.
  • the scan process is made by giving a start command to the computer and the scanning sequence is made automatically.
  • the point cloud result of every side of the object is obtained as an output of the scanning process (8) as shown in figure 2.
  • Shape acquisition is made by linear motion of the projection of the light stripe or stripes on the object.
  • step 1 the images of object with the stripe projected on is acquired by the camera and processed by the computer to get the shape information of the slice which the stripe is falling on.
  • the image taken by the color camera has three bands of red (301 ), green (302) and blue (not shown in figures) in step 2. If a red or green light source is used then the red band and the green band of the image is taken into the process in step 2. This means that according to colors of the light sources used in system (100), corresponding color bands are used for invariant calculation formula (i) given above. According to the light source projected to the object, the color invariants (303) are determined in step 3. In this process more than one color of light sources can also be used at the same time.
  • step 5 the image which the color invariants (303) are applied is thresholded, after said threshold is calculated as a percentage in step 4, according to the brightness of the ambient light; and as a result the stripe information is obtained clearly.
  • the result of the threshold contains only the stripe projected by the colored light source (304). The shiny parts and the noise occurring from the lighting conditions are not seen on the threshold image.
  • step 6 By processing the deformation of the stripe or stripes on the threshold image the depth information is obtained in step 6. This process is made by applying triangulation which applies trigonometric identities to find the distance of the point to the image plane in step 6. In step 7, it is decided whether the entire object scanned or not; if it is not completed, it is returned to step 1 and the same process is repeated by moving the stripe or stripes of light source along the object; when the scanning is finished, the 3D point cloud model of the object is created in step 8.
  • Using the color camera without any filter also allows obtaining the color texture of the object surface to be used further to reconstruct the object realistically.
  • the parameters of camera should be taken into account and the necessary calibrations of the scanner should be done according to the camera and the lens properties. Also the width of the stripe or the stripes determines the depth sensitivity and the resolution of the scanner.

Abstract

L'invention concerne un procédé permettant d'obtenir les informations de forme d'un objet physique tridimensionnel en utilisant un appareil photographique en couleur (102) et un projecteur de lumière colorée structurée (101). Un motif lumineux connu est projeté sur l'objet physique (107). La caméra en couleur capture cette projection. L'ordinateur (103) traite l'image colorée pour obtenir des informations de forme. Le procédé proposé permet d'extraire les informations de forme d'objets brillants ou spéculaires par l'utilisation d'un invariant colorimétrique. De plus, le procédé proposé permet d'extraire les informations de forme d'objets brillants ou spéculaires à la lumière ambiante.
PCT/IB2006/053772 2006-10-13 2006-10-13 Procédé permettant un balayage de lumière à structure tridimensionnelle d'objets brillants ou spéculaires WO2008044096A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/IB2006/053772 WO2008044096A1 (fr) 2006-10-13 2006-10-13 Procédé permettant un balayage de lumière à structure tridimensionnelle d'objets brillants ou spéculaires

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IB2006/053772 WO2008044096A1 (fr) 2006-10-13 2006-10-13 Procédé permettant un balayage de lumière à structure tridimensionnelle d'objets brillants ou spéculaires

Publications (1)

Publication Number Publication Date
WO2008044096A1 true WO2008044096A1 (fr) 2008-04-17

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WO (1) WO2008044096A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010133921A1 (fr) * 2009-05-21 2010-11-25 Yeditepe Universitesi Système de balayage de surface
US11074708B1 (en) 2020-01-06 2021-07-27 Hand Held Products, Inc. Dark parcel dimensioning
WO2022135635A1 (fr) * 2020-12-21 2022-06-30 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V. Détermination de défauts dans la courbe de la surface d'un objet à l'aide de réflexions colorées

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2078944A (en) * 1980-06-11 1982-01-13 Gen Electric Non-contact measurement of surface profile
US5057681A (en) * 1990-07-27 1991-10-15 Range Vision Inc. Long range triangulating coordinate finder
US20030026475A1 (en) * 2001-08-01 2003-02-06 Akira Yahashi Three-dimensional measuring method and device, and computer program
US20050116952A1 (en) * 2003-10-31 2005-06-02 Changsoo Je Method for generating structured-light pattern

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2078944A (en) * 1980-06-11 1982-01-13 Gen Electric Non-contact measurement of surface profile
US5057681A (en) * 1990-07-27 1991-10-15 Range Vision Inc. Long range triangulating coordinate finder
US20030026475A1 (en) * 2001-08-01 2003-02-06 Akira Yahashi Three-dimensional measuring method and device, and computer program
US20050116952A1 (en) * 2003-10-31 2005-06-02 Changsoo Je Method for generating structured-light pattern

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010133921A1 (fr) * 2009-05-21 2010-11-25 Yeditepe Universitesi Système de balayage de surface
US11074708B1 (en) 2020-01-06 2021-07-27 Hand Held Products, Inc. Dark parcel dimensioning
WO2022135635A1 (fr) * 2020-12-21 2022-06-30 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V. Détermination de défauts dans la courbe de la surface d'un objet à l'aide de réflexions colorées

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