Abstract:
This dissertation tests the hypothesis that thematic mapping of the Alice Springs area of Central Australia is possible from spacecraft. The range of imagery analysed included GEMINI and APOLLO colour photographs; LANDSAT Multispectral Scanner (MSS) images and computer compatible tapes (CCTs); SKYLAB black and white, colour, and colour infrared (CIR) photographs from the S-190A Multispectral Camera; colour and CIR photographs from the larger format S-190 B Earth Terrain Camera; and imagery and data from S-192 MSS digital tapes. Analysis of imagery included photographic, optical, electronic and digital processes. A three-tiered sampling model was used to test if boundaries recognised on space imagery represented real entities or were merely artefacts of the resolution systems of the spacecraft remote sensors. Comparisons were made between different spacecraft imagery and also with earlier CSIRO maps and reports derived from aerial photography and ground surveys. Resolution of all sensors other than SKYLAB S-190 B was too coarse to record detail. In the arid desert environment of Central Australia multispectral imagery contributed much less than is the case in more humid environments. The high resolution (17-3O m) of S-190 B resulted in greatly increased ability to map boundaries and record detail. A two-tiered sampling model, using the S-190 B photographs and sample field work, is possible with considerable potential time and cost savings. Comparison of CSIRO field maps with S-190 B high resolution colour photographs of the Kunoth Paddock area suggest that greatly improved accuracy of distribution would have been achieved if the space imagery had been available at the time of map preparation. The problem of variability among photo interpreters was tested. High resolution and familiarity with the areas being mapped gave the best results. Human subjectivity in unknown areas and with coarse resolution images results in much ambiguity and hence variation in defining boundaries. For the Alice Springs area improved resolution is superior to increasing the multispectral range. Computer processed digital data from both LANDSAT and SKYLAB S-192 MSS CCTs is potentially more useful for accuracy in mapping than photographic imagery other than the S-190 B. The surveys showed that thematic mapping from spacecraft is possible. New developments in spacecraft and remote sensors promise a great future for thematic mapping from orbital altitudes.