US 7,804,585 B2 · Creation of a range image

Abstract

The most difficult problem in the creation of a range image with stereo cameras is the establishing of the correspondence of the points. For this, the scene is illuminated twice; thereof at least once with a random or pseudo random pattern. For both cameras, an image is taken for each of the illuminations and the quotient of brightnesses is calculated pixelwise. The correspondence is established on the basis of a comparison of the quotient of pixels on epipolar lines of different cameras. The illumination pattern is preferably highly modulated along the epipolar line; transversally or diagonally to it, it is not or only slightly modulated. For illumination, a projection unit is used which in a preferred arrangement comprises two superposed grating patterns which have a distance (d) to each other, with at least one varying in a pseudo random manner, and with two closely neighboring light sources which shine through the gratings and thereby generate different pseudo random patterns, especially moiré patterns. Applications are found, inter alia, in assembly control, robotics, metrology, archaeology, in the textile industry, in biometry, medicine, reverse engineering.

Claims25

Dependent claims

Method for the acquisition of a range image of a scene from the correspondence of pixels of the images of a first camera and at least one second camera which record the scene in stereo arrangement, the method comprising:

illuminating the scene in a first illumination with a random or pseudo random pattern which is designed, with regard to at least one modulation feature in at least one spatial dimension, as a random sequence or, respectively, pseudo random sequence;
in the first illumination, a first image is taken by at least two cameras;
illuminating the scene in a second illumination, wherein a second image with the second illumination is taken by the at least two cameras;
calculating a ratio for at least two cameras, pixel-wise from the first and the second image taken by the corresponding camera in which a modulation feature value of the pixel from the one image is placed in the numerator, and the modulation feature from the other image is placed in the denominator of the ratio value;
and
determining the correspondence of pixels of the scene on the basis of a comparison of the modulation feature ratios of pixels from different cameras.

3 more elements

Dependencies are inferred from the claim text.

Creation of a range image

Life of this patent

Creation of a range image

Life of this patent

Abstract

Claims25