A photogrammetric stereoplotter using a stereoscopic binocular unit (1) to provide an image of spatially separated masters (4,5) and including a cursor (6) providing X Y coordinates and measuring marks providing Z coordinates in which the X Y Z coordinates are fed through a stereogrammetric unit (7) to a computer (8) with a display and/or printer (12,13) and an interface (14) to a display tube (16) and through an optic train (18) to at least one side of the binocular unit (1), and including a topographic keyboard unit (10) arranged to feed information to record the trace, and optionally a voice recognition unit (20) with two-way communication between operator and computer (8), and means in the computer (8) whereby model coordinates from the said binocular unit (1) are changed to image coordinates by the computer (8) to achieve precise superimposition of the trace image to eliminate visual disturbance.
A method for rigorously reshaping a pair of overlapping digital images using a Digital Photogrammetric Workstation (DPW) is disclosed. The overlapping images are imported into the DPW as a pair of originally distorted images having an associated sensor model. The original images are triangulated to adjust sensor parameters. Orthophotos are created with a flat digital terrain matrix (DTM) to leave terrain displacements within themselves, and according to a sensor model and formula for exact projective computations. The orthophotos are aligned by rotation, and interior orientation coordinates of the equivalent vertical frame images are determined. The orthophotos are imported as a pair of overlapping equivalent vertical frame images according to the interior orientation coordinates. A digital terrain model is generated in the DPW using the overlapping equivalent vertical frame images. Another orthophoto is produced using the digital terrain model to remove the measured terrain displacements. In an alternative embodiment, the equivalent vertical frame images are aligned by using the classical pair-wise rectification method or by separately rotating each image without aligning the orthophotos by rotation during their creation. In each embodiment, the sensor model of the original distorted images is dissociated from the orthophotos for subsequently greater distribution and usage of the stereo imagery.
A system and method for obtaining salient contours from two-dimensional images acquired by a sensor is disclosed which process the two-dimensional images with an edge detector to produce edgels from each of the images, link the edgels into lists known as contours, compute a saliency value for each of the contours, rank the contours in decreasing order of saliency, and select certain ones of the ranked contours based on the requirements of a particular vision application. Other devices, systems and methods are also disclosed.
Digitized stereo image pairs are analyzed by first aggregating the images to produce several levels of lower resolution images, bandpass filtering each of the images by applying a Laplacian filter to edge enhance the features, matching the features of low resolution images while generating a disparity image which contains elevation information, repeating the feature matching at successively higher resolutions and creating progressively improving disparity images, and extracting the elevation data from the final disparity image. The feature matching procedure uses an estimate of feature disparity to help locate a feature in one image which corresponds to a feature in another image and is applied iteratively at each level of resolution. Dilation of disparity data from matched points to neighboring unmatched areas produces a comprehensive disparity image which aids in more efficient feature location on the next pass.
Range discontinuities (44) in an imaged scene are located with superior accuracy by using a pair of stereoscopically related images (10, 12) of the scene to sense edges in the scene, and to determine the range of correlatable image pixels; segmenting the scene into regions (36) of similar intensity; assigning to each region (36) a range based upon the range of any correlatable pixels in it; and locating the boundary (44) between adjacent regions of substantially dissimilar range.
Two stereoscopic images of the surface of an inspected object are projected by two different lens systems to two separate video cameras for recording thereby and for display via a CPU on a 3D monitor. The optical axes of the two lens systems are equiangularly spaced from a central Z axis extending normal to the object plane, so that the height of a feature on the surface of the workpice may be calculated by determining the difference in the amount of lateral offset in the X direction from the center of a displayed image of a given feature as shown in one of the displayed images from the amount of its corresponding lateral offset in the other image, and then calculating Z in accordance with the formula Z=the difference in the offset in the X direction divided by twice the tangent of the angle of inclination of a respective viewing axis relative to the Z axis. Alternatively, the two images may be superimposed to form a stereoscopic image, and the two lens systems are shifted on the Z axis until the slight offset images of the feature coincide.
