Geometric Quality Testing of the Kompsat-2 Image Data Acquired over the JRC Maussane Test Site using ERDAS LPS and PCI GEOMATICS remote sensing software

Abstract

This report presents the geometric quality results recorded for the four samples of the Kompsat-2 radiometrically corrected images (processing level 1R) acquired over the JRC Maussane Terrestrial Test Site. The objective of this study is threefold: - to evaluate the planimetric accuracy in a routine basis production of orthorectified Kompsat-2 imagery; - to determine the optimal number and spatial distribution of the GCPs (Ground Control Points) for the Kompsat-2 orthorectification process; - to check if the orthorectified imagery of the Kompsat-2 optical sensor fall within the required accuracy criteria for the CwRS 1:10.000 scale of absolute 1-D RMSE of < 2.5m. The key issues identified during the geometric quality testing based on the limited Kompsat-2 sample images that were made available to us are as follows: 1. The 1-D RMS errors measured on the final K2 orthoimage after the single scene correction applying either the PCI rigorous model or the PCI RPC-based or the ERDAS RPC-based model are not sensitive to the number of GCPs used if they are well-distributed and range between 9 and 15 (provided a DTM with 0.6m vertical accuracy); and are sensitive to the overall off-nadir angle and increase with increasing off-nadir angle. 2. The average 1-D RMSE are 2.1m and 4m, while the maximum 1-D RMSE values are 3.2m and 6.2m of Easting and Northing direction respectively, provided a DTM with 0.6m vertical accuracy, and the GCPs with 0.05m < RMSEx, RMSEy < 0.90m are used. 3. The orthorectified Kompsat-2 imagery do not fall within the accuracy criteria of the CwRS 1:10.000 scale requirements, i.e. an absolute 1-D RMSE of < 2.5m (tab.20) except where the imagery is characterised by an overall off-nadir angle close to zero degrees and the rigorous model or first order Rational Polynomial sensor model is applied.