Method and tool for surface texture evaluation
First Claim
Patent Images
1. A method of evaluating texture of a surface, the method comprising:
- providing an image capturing device arranged to capture an image;
providing a source of light arranged to project light in a lighting direction;
locating the image capturing device along an orthogonal axis extending perpendicularly from the surface and facing the surface in a direction of the orthogonal axis so as to be arranged to capture an image of the surface;
sequentially projecting light onto the surface from each of four light source positions spaced circumferentially about the orthogonal axis;
arranging the lighting direction to be at a constant angle of inclination relative to the orthogonal axis in each of the four light source positions;
arranging an intensity of the projected light to be constant in each of the four light source positions;
capturing four images of the surface using the image capturing device in which the surface is illuminated by the light source from a respective one of the four lighting positions when each of the four images are captured;
determining if a specularity condition exists in one of the four images by comparing intensities of the images directly with one another;
if a specularity condition exists;
i) determining three images of the four images which are least affected by specularity; and
ii) determining a surface gradient of the surface using the three images.
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Abstract
Texture of a surface, for example concrete, is evaluated by capturing images of the surface facing the surface in a direction of an orthogonal axis extending perpendicularly from the surface while sequentially projecting light onto the surface from each of four light source positions spaced circumferentially about the orthogonal axis. A specularity condition is determined to exist in one of the four images by comparing intensities of the images directly with one another. If a specularity condition exists, three images of the four images which are least affected by specularity are used to determining a surface gradient of the surface.
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Citations
20 Claims
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1. A method of evaluating texture of a surface, the method comprising:
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providing an image capturing device arranged to capture an image; providing a source of light arranged to project light in a lighting direction; locating the image capturing device along an orthogonal axis extending perpendicularly from the surface and facing the surface in a direction of the orthogonal axis so as to be arranged to capture an image of the surface; sequentially projecting light onto the surface from each of four light source positions spaced circumferentially about the orthogonal axis; arranging the lighting direction to be at a constant angle of inclination relative to the orthogonal axis in each of the four light source positions; arranging an intensity of the projected light to be constant in each of the four light source positions; capturing four images of the surface using the image capturing device in which the surface is illuminated by the light source from a respective one of the four lighting positions when each of the four images are captured; determining if a specularity condition exists in one of the four images by comparing intensities of the images directly with one another; if a specularity condition exists; i) determining three images of the four images which are least affected by specularity; and ii) determining a surface gradient of the surface using the three images. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of evaluating texture of a surface, the method comprising:
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providing an image capturing device arranged to capture an image; providing a source of light arranged to project light in a lighting direction; locating the image capturing device along an orthogonal axis extending perpendicularly from the surface and facing the surface in a direction of the orthogonal axis so as to be arranged to capture an image of the surface; sequentially projecting light onto the surface from each of four light source positions spaced circumferentially about the orthogonal axis; arranging the lighting direction to be at a constant angle of inclination relative to the orthogonal axis in each of the four light source positions; arranging an intensity of the projected light to be constant in each of the four light source positions; capturing four images of the surface using the image capturing device in which the surface is illuminated by the light source from a respective one of the four lighting positions when each of the four images are captured; including; determining if a shadow condition exists in one of the four images by comparing intensities of the images to a prescribed threshold; and if a shadow condition exists; i) determining three images of the four images which are least affected by shadow; and ii) determining a surface gradient of the surface using the three images.
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Specification