Evaluation of the quality of generated orthoimages from PRISM/ALOS-2: A case study for São Gabriel, Rio Grande do Sul, Brazil

The focus of this study was the generation and evaluation of ALOS/PRISM orthoimages using DEMs (Digital Elevation Models) derived from distinct combinations of sensor viewing from a 1B1 image processing level. The studied area chosen was a rural one located in São Gabriel municipality, in the State...

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Bibliographic Details
Published in:GAEA (São Leopoldo, Brazil) Brazil), 2012-01, Vol.8 (1), p.6
Main Authors: Angela Akemi Goto Nakahori, Sérgio Florêncio de Souza
Format: Article
Language:Portuguese
Subjects:
Case studies
Earth science
Rural areas
Sensors
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Summary:The focus of this study was the generation and evaluation of ALOS/PRISM orthoimages using DEMs (Digital Elevation Models) derived from distinct combinations of sensor viewing from a 1B1 image processing level. The studied area chosen was a rural one located in São Gabriel municipality, in the State of Rio Grande do Sul, Brazil, which is nearly flat (average altimetry 160 m). In the first stage the DEMs were generated using a combination of the three viewing and control points obtained through field survey. Among other parameters, the minimum amount of control points needed that could generate the MDE, the processing level and the window size were tested. Next, two results were compared: the extraction with ASTER (GDEM) Digital Elevation Models and SRTM (Shuttle Radar Topographic Mission), which was generated from the Project TOPODATA from the National Institute for Space Research (INPE, 2009). Finally, the DEMs with the checkpoints were evaluated and the best DEMs for orthorectification were selected using statistical analysis. The results showed that for this specific study all DEMs combining views Backward-Forward generated from the control points would be approved, since they have the lowest values of RMS (Mean Square Error between 2.94 and 3m). Moreover, it was shown that when using DEMs from other combinations, the orthoimages obtained also comply with the Cartographic Accuracy Standard (PEC) for Class A scale 1:25,000 as well as the orthoimages generated from Global SRTM Elevation Models and GDEM. The flatness of the studied area seems to be the main reason for the good performance achieved by SRTM together with the PRISM generated DEMs.
ISSN:1808-5261
1983-3628