Topographic Mapping - Products
The Coordination of Cartography of IBGE (CCAR) has conducted studies on the development and implementation of a methodology for the use of orbital images in the cartographic production. Its purpose is to offer cartographic databases for unmapped regions and mapped regions with out-of-date maps in a faster and more economic way. The MA/PA-100 Project is particularly concerned with the difficulties of access to the low lands and indentations of the state of Maranhão, caused by the local climate and poor roads.
In order to conduct the mapping of the region, panchromatic orbital images from the Spot 4 satellite (10-m resolution), Landsat 7and CBERS 2 images and the Digital Terrain Model (DTM) of the SRTM (Shuttle Radar Topographic Mission) were used. Field missions were conducted to obtain the coordinates of points for the orthorectification of images, reambulation and GPS assessment of the features of interest (compatible with the 1:100,000 scale). The map sheets were structured in alignment with the Brazilian systematic mapping. The planimetric reference system is SIRGAS 20001, and the Projection System is the Universal Transverse Mercator (UTM), 45o WGr central meridian.
Each map sheet is composed of DGN format files, one for each category of interest and one for the grid of each map sheet, in the projection aforementioned. The categories of interest were hydrography, tranportation system, locations, repairs and construction 1, repairs and construction 2, repairs and construction 3, vegetation, reference point and indigenous area 2. The vegetation category is not as consistent as the other categories, since it is inherently heterogeneous and the input used is limited . Therefore, it was assessed considering the area covered by the predominant species.
The material is organized as the following structure of directories:
Work_Files: These files refer to the standard applied to the vectorial representation of elements: library of cells (Topo50_09jun06.cel), library of fonts (ibgeustn_v2.rsc) and table of colors (plotv10.tbl). They also include the Elementos_Graficos.pdf document, which lists all the elements represented on the map sheets, with the identification of the graphic features.
Vector_Files: These files include the DGN files corresponding to each map sheet available, sorted in folders named NomeFolha_MI.
The MA/PA-100 Project makes available the vectorial files of four of its twenty-two map sheets. The map sheets can be used in the Geographic Information System because they are topologically consistent and integrated 3. Although they have not been normalized for printing (editing) yet, what will be done in 2006, they can be viewed and their features can be comprehended by checking the available documents.
1 - For practical purposes, in this scale of work, the horizontal datum was assumed to be WGS84.
2 - The information is approximate and it is different from that provided by FUNAI.
3 - Except when it was not possible to confirm the information of the previous mapping.