Application of digital terrain data to quantify and reduce the topographic effect on Landsat data

Integration of Landsat multispectral scanner (MSS) data with 30 m U.S. Geological Survey (USGS) digital terrain data was undertaken to quantify and reduce the topographic effect on imagery of a forested mountain-ridge test site in central Pennsylvania. Four methods for reducing the topographic effect were compared; band ratioing and three radiance models. Band ratioing did not eliminate the topographic effect due to the lack of variation in MSS4 radiances. Of the three radiance models applied to the data, the lambertian and modified lambertian models increased the topographic effect. The non-lambertian model considerably reduced (86 per cent) the topographic effect in the Landsat data. The study demonstrates that high quality digital terrain data as provided by the USGS can be used to enhance the utility of multispectral satellite data.