Several advanced technologies have become available for primary data acquisition of geospatial data as well as digital elevation model (DEM).
Following advanced technologies will be useful for future GIS.
a. Electronic Plane Surveying System
An integrated system of total station with automated tracking function, kinematic global positioning system (GPS) and a pen computer (see Figure 3.10 (a)) will replace the conventional plane surveying. Direct data acquisition in digital form, at the field site will be very useful for large scale GIS data set, for example in the application to cadastre, utility facilities, urban structures etc.
b. Mobile Mapping System
Different sensors such as GPS, INS (inertia navigation system), more than two digital cameras, voice recorder etc. are fixed on a vehicle as shown in Figure 3.10 (b) in order to map objects in close range. For example center line of highways, utility lines, railways etc. as well as to determine trajectory of the moving vehicle.
c. Laser Scanner
Airborne laser scanner together with GPS and INS will measure directly the terrain releif or DEM as shown in Figure 3.10 (c) with the height accuracy of 10 cm up to the altitude of 1,000 m.
d. SAR Interferometry
SAR (synthetic apperture radar) inter-ferometry is a new technology to produce DEM automatically by special interferometric processing of a pair of SAR images. Airborne and space borne SAR interferometry are now available if the inter-ferometric condition meets the standard.