Chapter 16. Raster data digitalization

The GROMA program allows acquisition of the point coordinates by processing the raster data. The files with raster data can be gained by scanning map sources.

The existing program version allows processing of the raster data into the bitmap format .bmp files, eventually .dib).

Loading raster data in the program

To process raster data, you have to first open a window with the relevant file. A raster data window can be opened in the same way as any other data window. When opening the file, you have to select the item Bitmaps from the list Files type. The program then offers all the files with the extension .bmp found in the active directory.

After selecting a file, the program will first try to open a file of the same name having the extension .rnf. in the relevant directory. Such a file would contain the raster data information (identical points, transformation key, etc. ). If no .rnf file is found, the program will create a new one. In case of terminating and re-launching the program (e.g. in case of its failure) while entering the identical points for transformation in this file, you can continue the digitalization without the need to re-determine of the transformation key because the file is automatically saved.

The transformation key refers to the relevant file, not to a window; more than one window with a bitmap can be open at the same time, and one transformation key will be valid in all of them (therefore you can determine it only in one arbitrary window).

Just as for the coordinate files, more than one raster data file can be open at the same time. The program will automatically use the pertinent transformation key during the digitalization of each file. If you have opened the dialog window for determination of the transformation key (see further), the program displays the data related to the window where the mouse cursor is currently located in it. If you move the cursor from one raster data window to another, the program immediately displays the identical points of the other file.