Satellite Image Interpretation for Mapping Purposes. / November 9, 2004 /
There exist several factors that determine the preference of space imagery use:
- Mapping products with less details (as compared with topographic maps of comparable scale) are needed
- A large spatial coverage with generated or updated map of medium scale (1:25000-1:50000) is required.
- Mapping of those objects that are not shown in topographic or other special-purpose maps or are shown with poor accuracy (swamped territory extent, small lakes, wood tracks) is required.
- Determination and mapping of special features of objects (e.g. type of area disturbance, wood-cutting site parameters etc.) are required
- • Inventory of changes in territory that took place for some time past including changes in some certain objects (e.g. mapping of man-made changes to be submitted to Land Committee and other supervisory bodies) is required.
There is one more factor of no small importance: the more multipurpose is image use, the more profitable is its purchasing. For instance, the purchasing of image for purposes of, for example, tree felling control within protective zones of territories of particular protection seems to be unprofitable for Nature Conservation Committee. However if the same image is used to derive data on afforestation, wood-cutting area parameter control, to update the available 1:25000-1:50000 maps by some elements, to generate roadmaps (including forest roads), to derive data on submerged territories and engineering services, to control building sites beyond the boundaries of land grant, etc., we may say about comprehensive profit for many of business entities and public authorities which will use the data obtained in their activities.
What Is the Mapping Technology Using Satellite Images?
Briefly the technological process of space image processing involves the following key stages:
There are several methods for map object content forming: visual interpretation, automatic interpretation with training, and index estimation. When visual interpretation, object identification is based on special-purpose documents: interpretation atlases indicating typical images of objects, their distinctive features, techniques of their mapping. Visual interpretation allows for generating most of thematic general maps, map updating and multi-source cartographic information adjustment. Automatic interpretation requires firstly reference object identification (e.g. woods of certain type, well-known area of oil pollution etc.) to be used for program education. In the future, this program will recognize automatically the types of objects at which the program is set. This method is used for compilation of component by component maps such as maps showing forest stand types, stationary smoke jets etc.
Mapping Results Using Satellite Images.
Figure 1:Segment of digital map hard copy of catch water drain compiled from the processed SPOT image (reduced image). Forest management compartment network reconciliated and corrected by satellite image and protective zone of marsh reservation derived from the peat deposits interpretation are seen in the map in addition.
Figure 2:Water protection zone calculation and shelter belt size specification using satellite image (reduced image). Permissible minimum dimensions of water protection zones (according to the instruction) calculated by the distance from river head are marked by red. The sites of more than 3 degrees in slope detected by Digital Terrain Model are given in brown. Satellite image is used for interpreting such parameters as activity in protective zones, afforestation, tilled lands, drainage polluting objects etc.
Figure 3:Swamping of an area (marked by arrows) due to narrow-gage railroad embankment preventing from surface runoff
Figure 4:Satellite images used for tasks of State Land Control. The image shows a section of engineering serves which cutting is illegally occupied under potato.
Figure 5:Polluted snow cover near oil fields. The data derived from the image interpretation will enable pollution source to be localized and their intensity to be assessed.
Figure 6:Scheme illustrating the interpretation of loggings. The interpretation results enable the determining with an image resolution accuracy of such parameters as actual acreage of felling area, its position adequacy to allotted land, seed beds and seed strip arrangement, wood-cutting area adjoining, deforestation in protective zones, orientation with reference to cardinal points, wood-road laying by stream canals etc.
Figure 7:Deforestation within the territory of protective zone of marsh reservation. The deforestation sites located directly in the protective zone are marked by arrows. Conservation area is marked by red line
Figure 8:Examples of terrain change interpretation (monitoring) for compiling man-made change maps
Figure 9:Examples of terrain change interpretation (monitoring) for compiling man-made change maps.