Process for detecting surface defects on a textured surface
First Claim
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1. Process for detecting surface defects in a substantially plane textured surface,wherein it comprises the following steps of:
- a) making, with the aid of an optical sensor presenting an inclination of sight with respect to the substantially plane textured surface and being in relative movement with respect to this surface, a succession of images of parts of this surface at successive instants, each image corresponding to a surface part of length L in the direction of displacement, each image being offset from the preceding one by a length 1, 1 being equal to L/K with K, a whole, greater than 2;
b) defining sub-images corresponding to elementary portions of the surface whose length is equal to 1 in the direction of displacement, whereby for the length of portion of surface 1, K sub-images of this portion are available;
c) extracting from these K consecutive sub-images N sub-images (Ii) corresponding to the same portion of the surface of length 1 at N successive instants with N included between 2 and K;
d) applying to each of the N sub-images (Ii) the same spatial mathematical processing in order possibly to demonstrate a configuration of presumed defect, which gives a processed intermediate sub-image (Yi);
e) applying to the first processed elementary sub-image (Yo) a combinatorial algorithm for detection of presumed defect in the elementary sub-image, whereby a spatial and temporal sub-image ST0 is obtained;
f) iteratively repeating the application of said combinatorial algorithm to the spatial and temporal sub-image STi-1 obtained at instant ti-1 and to the processed elementary sub-image Yi in order to obtain a spatial and temporal sub-image STi up to i=N-1; and
g) obtaining with the spatial and temporal sub-image STN-1 the image of the elementary portion of the textured surface with its possible defects.
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Abstract
A process for detecting defects in a textured suface, particularly on a highway. The process consists in displacing with respect to the surface a camera presenting an inclination and in processing by processing systems the successive images taken by the camera. A mathematical processing is effected on sub-images, corresponding to the same spatial portion of the surface, taken at different consecutive instants.
36 Citations
9 Claims
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1. Process for detecting surface defects in a substantially plane textured surface,
wherein it comprises the following steps of: -
a) making, with the aid of an optical sensor presenting an inclination of sight with respect to the substantially plane textured surface and being in relative movement with respect to this surface, a succession of images of parts of this surface at successive instants, each image corresponding to a surface part of length L in the direction of displacement, each image being offset from the preceding one by a length 1, 1 being equal to L/K with K, a whole, greater than 2; b) defining sub-images corresponding to elementary portions of the surface whose length is equal to 1 in the direction of displacement, whereby for the length of portion of surface 1, K sub-images of this portion are available; c) extracting from these K consecutive sub-images N sub-images (Ii) corresponding to the same portion of the surface of length 1 at N successive instants with N included between 2 and K; d) applying to each of the N sub-images (Ii) the same spatial mathematical processing in order possibly to demonstrate a configuration of presumed defect, which gives a processed intermediate sub-image (Yi); e) applying to the first processed elementary sub-image (Yo) a combinatorial algorithm for detection of presumed defect in the elementary sub-image, whereby a spatial and temporal sub-image ST0 is obtained; f) iteratively repeating the application of said combinatorial algorithm to the spatial and temporal sub-image STi-1 obtained at instant ti-1 and to the processed elementary sub-image Yi in order to obtain a spatial and temporal sub-image STi up to i=N-1; and g) obtaining with the spatial and temporal sub-image STN-1 the image of the elementary portion of the textured surface with its possible defects. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification