ABSTRACT:In order to determine the absolute accuracy of SRMT model on Polish area the research work has been performed on the basis of reference terrain profiles measured by GPS technique. The flat and hilly terrains were examined in administrative borders of fourteen provinces. It was not reference data for mountainous terrains. For the analysis of accuracy of the SRTM model 332 terrain profiles and 29,308 points have been measured. The accuracy of SRTM model presented by RMSE was computed on the basic of the height differences between profiles and models homolog points. The analyses have been done in Modular GIS Environment Intergraph software. The absolute accuracy of SRTM model on Polish area RMSE Z = 2.9 m for flat regions and RMSE Z = 5.4 m for hilly regions were achieved. It was affirmed that this accuracy is depend on the resolution of grid points of DEM and terrain inclination. The statistic estimation showed systematic shift between SRTM data and reference profiles. The RMSE Z without systematic part was found to be 1.0 m for flat regions and 2.7 m for hilly regions of Polish area. The data of SRTM level DTED-1 could be used for DEM and contour lines generation on the topographic maps in scales smaller then 1:50,000 and for SRTM system calibration.
Aerial photographs taken over the past 80 years are often the only record of topography and events that have been destroyed or obliterated. However, the lack of camera certificates for many historical photographs, and their physical degradation, often makes it challenging to correct them geometrically. In this paper, we present the process of orthorectifying archival Luftwaffe aerial photographs of the area of the Treblinka extermination camp from May 1944, based on a computer vision-based process and preprocessing techniques. Low-cost and easily accessible software was used, which allowed for the generation of a fully metric orthophotomap in a repeatable and accurate way. This process can be repeated for archival aerial photographs from other dates (for the Treblinka camp) and other extermination camps (Belzec and Sobibor).
Nowadays, archival images find increasingly finding their way into geospatial applications, namely, among others, multi-temporal analysis, documentation reconstruction or change detection. It is, therefore, necessary to determine the images' external orientation elements that allow the images' position to be reconstructed in the assumed reference system. This paper aims to present a methodology for the extended evaluation of the automatic orientation process of archival images based on the commonly used Structure-from-Motion (SfM) approach. The work carried out presents: (1) the influence of parameter selection on the accuracy, number and distribution of tie points in the descriptor matching process at the pairwise image bundling stage using the descriptor matching approach together with the use of Random sample consensus filtered triangulation (RANSAC), (2) analyses of the reciprocal orientation quality of the images on detected points (control points) in the bundle adjustment process using simultaneous verification of the matching quality on check points, and (3) analysis of the external orientation accuracy. Points detected and matched using the SIFT algorithm on archival images of a fragment of Warsaw from 1986, 1994, and 2014 were used as reference data. A comparative analysis of the obtained results with the data obtained using the algorithms implemented in the Agisoft Metashape software (standard approach) shows that the relative orientation reprojection RMSE is about 4 time better, and detected points are even more robust.
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