Teang Peng Seang
Geoinformatics Education Centre (PGEC), Cambodia
Email: [email protected]
CIM/gtz – Cambodia
The paper introduces and assesses the highly efficient amateur aerial balloon photo technique, which makes aerial photos affordable at a price of 0.10 – 0.35 US cents per hectare. The idea was to provide an inexpensive but quality efficient solution for recent aerial color photos on a high pixel resolution while orthographic images are not everywhere accessible in Cambodia. Other high resolution images from advanced scanners like Quickbird, Ikonos or others are most likely unaffordable due to insufficient decentralized budget in Cambodia. As a consequence topographical and other spatial data are more or less missing in planning offices and enhancement and modifications basically are not easy to integrate into smaller scaled planning resources. This modern technique is based on a simple plastic balloon (r=3m), inflated with hydrogen gas, chemically produced on the site and adapted to the conditions in developing countries especially for areas with rapid land use changes. In Cambodia it is presented by a private geo-spatial company, the Phnom Penh Geoinformatics Education Centre (PGEC) in collaboration with the Faculty of Land Management and Land Administration at the Royal University of Agriculture. The rectified, merged and geo-referenced aerial balloon-photos with surface resolution per pixel vary among 20m to 0.4m, depending on altitude of the platform and camera capacity, are enlargeable up to a scale of 1:1.000 without any loss in optical and spatial quality. Methodologically the approach uses typical image processing, enhancement and geo-referencing techniques like haze elimination, merging and mosaic procedures, mostly provided by ERDAS IMAGINE software. The aerial photo collection follows standard aerial photo measures like flight line preparation, synchronization of camera and GPS clocks as well as ground truth samples. The balloon based digital aerial photos from an non calibrated digital camera (Olympus C-70) are already integrated in decentralized regional and urban planning processes in Cambodia as well as geospatial education, data trainings. Further outcomes of this technique are lately renewable detailed land use maps as well as other planning sources for real estate validation and environmental protection strategies i.e. buffer zoning concepts. Besides, they are expected to be useful for other “small area” projects like village based land use planning, technical implementations or (eco-) tourism projects at specific locations and retakes of the same photos within a high-level time resolution of one or two years.