High-resolution Satellite Imaging for Digital Surface Models

Elevation information is an important component of any geospatial database. It is imperative for applications such as topographic mapping, spatial and temporal change detection, feature extraction and visualisation. Although elevation data may in cases be purchasable from government agencies, the availability of alternative sources of data, such as space imagery, coupled with increased user confidence in technology, it is now viable for consumers to produce their own spatial datasets. With commercial-offthe-shelf (COTS) software, operators with limited expertise can easily create their own application specific project. This paper will provide a detailed study on the accuracy and performance of elevation extraction from COTS software, with emphasis on digital surface models (DSMs) generated from high-resolution satellite imagery. The evaluation is important due to the high cost investment associated with these systems. In checkpoints favourable to image matching, accuracy to a few pixels in height can be achieved from COTS DSMs; however the isolated points are unlikely to be representative of the entire testfield. Therefore, we look to alternative sources of control, such as the newly available DLRand NASA-generated SRTM DEMs. A comparison to X-band SRTM DEMs showed that height RMSE values range from 4 – 9 metres, though most of this uncertainty is attributed to the SRTM data.