The potential of combined use of satellite data with topographic information

Landsat Thematic Mapper, SPOT panchromatic and SPOT MSS imagery from 1986 were investigated for their capabilities of keeping topographic maps up to date. Topographic information was digitally combined with satellite data using raster techniques. From the map line-information on roads, naming-conventions, water and housing was used to cover a minimum part of the image and to obtain a maximum geographic reference structure in the imagery. A product with optimum characteristics was composed of a SPOT-panchromatic band, a SPOT HRV- infrared band and a themefile with topographic information. The size of the files, limits applications to manual procedures. Updating is limited to features of at least 4 m wide. The topographic overlay increases the user-friendliness of satellite data. Thematic information (on landuse) can be combined with satellite imagery in a similar way as carried out with linear features in this study. This can supply a highly detailed stratification of a region in functional classes, permitting classification procedures to achieve better results. Paper presented at the Willi Nordberg Symposium, Austra, Graz, September 1987, Remote sensing towards operational carthographic application.