US 7,023,559 B1Granted

Method and system for measuring the relief of an object

AssigneeSolvision Inc.

InventorsAlain Coulombe, Michel Cantin, Alexandre Nikitine

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Abstract

A method and a system for measuring the relief of an object are described herein. The system includes a grid projecting for projecting a grid, an image acquisition apparatus that includes a camera, and a computer. Providing a reference object having common elements with the object to measure, the method includes the steps of a) positioning the grid at three different known positions relative to the camera and the common elements; b) for each position of the grid, projecting the grid unto the reference object and, with the camera, taking an image of the reference object to yield three images having values for each pixel of the camera and c) computing the reference object phase for each pixel using the three reference object intensity values for the corresponding pixel. Steps a), b) and c) are repeated by replacing the reference object by the object to be measured. The difference of height between the object to be measured and the reference object for each pixel are then computed by subtracting the reference object phase and the object phase for the corresponding pixel.

Claims16

Dependent claims

A method for measuring the relief of an object using a camera provided with an array of pixels, said method comprising the steps of:

a) projecting a grid on a reference object;
the grid being located at a first position relative to the camera and to the reference object;
b) taking, with the camera, an image of the reference object illuminated by said projected grid;
said image of the reference object having intensity values for each pixel;
c) repeating steps a) and b) at least two times with the grid being located at two different known positions relative to the camera and to the reference object to yield at least three intensity values for each pixel;
d) computing the reference object phase for each pixel using the at least three reference object intensity values for the corresponding pixel;
e) projecting the grid on the object;
the grid being located at said first position;
f) taking with the camera an image of the object illuminated by said projected grid;
said image of the object having intensity values for each pixel position;
g) repeating steps e) and f) at least two times with the grid being located at said two different positions to yield at least three intensity values for each pixel;
h) computing the object phase for each pixel position using the at least three object intensity values for the corresponding pixel;
and
i) computing the difference of height between the object and the reference object for each pixel using said reference object phase and said object phase for the corresponding pixel;
and
j) using said difference of heights between the object and the reference object for each said pixel to determine the relief of the object.

13 more elements

Dependencies are inferred from the claim text.