The technical procedures for producing maps using satellite images or aerial photographs are in reality quite complicated and it is necessary to refer to the appropriate literature for detailed description of processes involved. The following procedures are designed to provide a general overview of the main steps required to produce a base map using satellite images:
- Identify the map features necessary for the planning process (e.g. physical features, settlements, contour lines, roads, rivers, etc.).
- Determine the necessary scale (e.g. 1:50.000, 1:100.000); accuracy and classification of the data required.
- Identify institutions, organizations or even private companies that have the necessary information (i.e. secondary sources) and who maybe willing to provide the data. Examine the data they have available (i.e. research of their meta data bases) and derive the data needed for the maps that should be developed. If no data is available, continue with step 4.
- Purchase the required satellite imagery / aerial photography.
- Develop / adopt technical procedures for extracting required information from satellite imagery (pre-processing, rectification, image enhancement, classification) using a pilot area.
- Digitise and update the map features according to standardized routines.
- Assess and improve the quality of map data through selected ground surveys and field verification and cross-check the information with other maps.
- Reclassify the map data, if deemed necessary.
- Carefully document the technical procedures that were used to develop the new or updated maps.
- Share the new map data with other institutions or organizations who either participated in the whole exercise or who have an interest in using the newly developed maps.