Showing papers on "Change detection published in 1980"

Digital Image Change Detection

Abstract: Multiple views of a scene generally contain informa-tion that is implicit in the differences between the views. Such information can be of great interest when images are taken under different conditions or at different times, as it may provide insight into underlying physical or biological processes. Digital image change detection permits to detect and helps interpret such change information where the human observer otherwise fails. The method described here produces a "change image," which portrays image differences according to a simple convention. In the change image, previously invisible differences clearly stand out, often in meaningful patterns, and they can be further enhanced for easy visual interpretation. Examples are presented of this method applied successfully in widely different fields - remote sensing, radiology, nuclear medicine - illustrating the potential of digital image change detection, and also suggesting further avenues of research.

SAR Object Change Detection Study.

Abstract: : This study assessed the applicability of three area-based change-detection algorithms to the problem of recognizing differences between two images. These approaches are based on defining sets of descriptors for small regions of each scene and then comparing these sets of descriptors to indicate areas of change. The first algorithm is based on the phase-correlation concept--a technique for extracting accurate estimates of the relative displacement of two images from the phase of their cross-power spectrum. The 2nd is based on using a subset of power-spectral coefficients for each image--the subset is chosen to minimize differences due to scene bias, shading, or high-frequency noise content. The 3rd is based on defining image moments and a set of functions of these moments which are invariant with respect to a number of geometrical distortion or scale changes of the image. These algorithms were applied to furnished SAR images. Results of the three algorithms are consistent among themselves but correlate weakly with known ground truth. Studies to determine the size of targets that can be reliably detected by use of these methods indicate that the size of targets in the furnished images fails to meet the size criterion for reliable change detection. It is concluded that, for imagery of this quality and resolution, target detection and association algorithms should prove to be more effective for change detection.

Urban area change detection procedures with remote sensing data

Abstract: The underlying factors affecting the detection and identification of nonurban to urban land cover change using satellite data were studied. Computer programs were developed to create a digital scene and to simulate the effect of the sensor point spread function (PSF) on the transfer of modulation from the scene to an image of the scene. The theory behind the development of a digital filter representing the PSF is given as well as an example of its application. Atmospheric effects on modulation transfer are also discussed. A user's guide and program listings are given.