Author/Editor		Zelasco, Jose Francisco; Ennis, Kevin; Blangino, Eugenia A
Title		Quality control in altimetry and planimetry for 3D digital models
Type		članek
Source		Image Anal Stereol
Vol. and No.		Letnik 20, št. Suppl 1
Publication year		2001
Volume		str. 360-5
Language		eng
Abstract		Digital elevation models (DEM's), usually obtained by means of different systems of image processing, particularly stereoscopic ones, do not have the same error in altimetry and in planimetry. The "a priori" studies performed on models based in photogrammetry or in SPOT satellite images show the difference of precision in z coordinated with respect to that of the (x,y) plane. It is noted that in the literature there are no appropriate methods for "a posteriori" quality control of the DEM; this is, then, an open problem. After having faced several solutions in altimetry derived from error studies in planimetry (based on the Hausdorffs distance), and diverse simulations carried out with no satisfaetory results, we decided to study the problem from another point of view. The proposed solution presented in this work consists in determining the "a posteriori" values of the altimetric and planimetric errors, based on a canonical least squares estimator for the variance, using the geometrical properties of the error ellipsoids of the model with respect to the reference surface. The method takes as observable the distance from the points of the DEM to the surface of a reference DEM. The estimator is defined as the square of the measured quantities. The results of many simulations and numerical experiments for several sets of conditions, that are shown in this paper, with profiles and surfaces are very encouraging.
Descriptors		LEAST-SQUARES ANALYSIS PARTICLE SIZE IMAGE PROCESSING, COMPUTER-ASSISTED MODELS, THEORETICAL