Construction of a Global Map Around Mindanao, Philippines/1
For the vector GIS data, the Digital Chart of the World (DCW) was used. The DCW is a comprehensive database, composed of global coverage base maps at 1:1.000.000 scale. It consists of geographic, attribute, and textual data that can be accessed, queried, displayed, and modified with ARC/INFO
TM and Are View
TM software. The database was originally developed by SERI in vector Product Format(VPF) for the United State Defense Map Agency (DMA). The primary source for the database is the DMA Operational navigation Chart (ONC) series that are produced by Australia, Canada, the United Kingdom, and the United States(1).
For landcover data, the Global Land Cover Characteristics Database was utilized. The Global Land Cover Characteristic Database has 1-km resolution, for use in a wide range of environmental research and modeling applications. The database is a product of the US Geological Survey (USGS) (EROS Data Center ) , the University of Nebraska-Lincoln (UNL) and the Joint Research Center of the European Commission.
Table1.Data sources for the construction of global Map around Mindanao , Philippines .
All data available for global mapping requires intense preparation before being used. In case of DCW , data was already prepared for using with Arc View
TM. But GTOPO30 and Land Cover Data have to be previously prepared by the GST staff in order to be used in the study . They extracted the sample areas from different files adapting and changing different projections and formats of data .
The sample areas ware extracted the different files, adapting and changing different projection and formats of data .
The necessary DCW data ware selected from the 5 x 5 degrees tiles to complete the sample study areas . For this exercise, the sample area references were tile numbers WG12 and WG22 corresponding to the area around Mindanao , Philippines , of the DCW files .
The projection conversion program was accessed through the global land Cover Characterization - Global Read me 7.0 (Geometric characteristics, software for latitude / longitude conversion ) available via the Internet by file transfer protocol (FTP).
All of the image file had the following specification: 5 x 5 degrees means 600 x 600 cells each cell being equal to 30' x 30', and extracted without header. These files were then subsequently converted to .TIFF files in an appropriate image processing software such as the Adobe Photoshop
TM or any similar software like , GeoSTAR
TM. It is necessary to build an index file for vegetation, and join the pieces to make one file to overly with other vector files.
As mentioned earlier, the available image processing software most appropriate for this conversion is Geo STAR
TM.
The image files(.TIFF) necessary for the subsequent steps must be constructed, which should include the right header coordinates in order to visualize them . At the file .TWF the coordinates of the upper left corner, or the size of the pixel) can be selected , copied or inputted through a text editor.
It should be noted that the same header must be used for all .TIFF image files since the image layers have the same number of rows and columns, correspondingly, the same longitude and latitude . For these processes the .TFW files for each image tile must be renamed for each image layer , by copying and saving with the same files name of the tile, but with distinctive file extension of .TFW. (e.g. tiles WG12.TIF and WG22.TFW, Respectively). The TFW files contain coordinate information .
