Robert A. Schowengerdt

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A detailed comparison of the backpropagation neural network and maximum-likelihood classifiers for urban land use classification is presented in this paper. Landsat Thematic Mapper images of 'heson, Arizona, and Oakland, California, were used for this comparison. For the " a n image, the percentage of matching pixels in the two classification maps was only(More)
This paper investigates airborne helicopter video for estimating traffic parameters. Roll, pitch, and yaw of the helicopter make the video unstable, difficult to view, and the derived parameters less accurate. To correct this, a frame-by-frame video-registration technique using a feature tracker to automatically determine control-point correspondences is(More)
This paper is a 1-D analysis of the degradation caused by image sampling and interpolative reconstruction. The analysis includes the sample-scene phase as an explicit random parameter and provides a complete characterization of this image degradation as the sum of two terms: one term accounts for the mean effect of undersampling (aliasing) and nonideal(More)
Rectification or geometric correction of digital images refers to the 2-dimensional resampling of an image data array onto a new grid which is distorted with respect to the original grid. When an image on a mass storage device is very much larger than the available computer central memory, it is important to choose an algorithm for rectification which(More)
Respiratory gating and tumor tracking for dynamic multileaf collimator delivery require accurate and real-time localization of the lung tumor position during treatment. Deriving tumor position from external surrogates such as abdominal surface motion may have large uncertainties due to the intra- and interfraction variations of the correlation between the(More)
A dynamic multi-leaf collimator (DMLC) can be used to track a moving target during radiotherapy. One of the major benefits for DMLC tumor tracking is that, in addition to the compensation for tumor translational motion, DMLC can also change the aperture shape to conform to a deforming tumor projection in the beam's eye view. This paper presents a method(More)