Starting a new project
When you start a new project with CorrMap, the only thing you need is the map raster file that you want to geo-reference, calibrate or rectify. In this case, you don't use the File | Open menu option as you might think, but File | New instead. In fact the File | Open command is used to open a CorrMap generated .GMP file, i.e. a raster map already treated by CorrMap, whereas now you want to open an original non-geo-referenced raster map.
To do this, with reference to Fig. BO.1, open the CorrMap File menu by clicking on the icon that symbolizes the program in the upper left of the screen (1) and activate the New option (2):
Fig. BO.1 – To geo-reference, calibrate or rectify an original new map, just activate the File | New menu command.
This option opens the Windows dialog box for selecting raster image files (BMP, JPG, TIF, PNG, etc.). So, all you need to do is to browse your computer to locate the folder containing the map you want to work with. Once you have selected your map raster file, CorrMap opens the window shown in Fig. B0.2 in which the program asks you to define the nominal scale of the map and the interval between its grid lines (if present). These two items of data are needed in some CorrMap geo-referencing techniques, so they are requested at this initial stage in order to avoid re-entering these values for each transformation.
Fig. BO.2 – Before opening a new map CorrMap asks you the scale/grid information.
You can select these two values from the list in the window or, if they are not present, you can just type them in the two cells. In either case, then click the Apply button to confirm and proceed. Otherwise, if you are not sure of the scale value, or your map does not contain grid-lines, you can skip this operation and post-pone it till later. To do so, simply click the large button The map does not contain grid lines / I will manually insert this information later at the bottom of the window. Once you have done with this window, your map will be opened in CorrMap and you can go on to perform the transformation you need by selecting the corresponding tab from the 6 techniques offered by the program, shown in Fig. BO.3 (the Home tab contains a series of basic commands explained in the other chapters of the Basic Operations section).
Please refer to the chapters of the Transformations section for the explanation on how to perform each transformation.
Fig. BO.3 – Once you have opened the map, chose the desired transformation among the 6 ones provided by CorrMap.
As mentioned above, if from the scale/grid window of Fig. B0.2, you clicked the button The map does not contain grid lines / I will manually insert this information later, you can still define the values for those transformations which require them, i.e. the Affine and Grid transformations. To do so, firstly go to the Affine transformation and select the desired scale value from the drop-down Nominal cell, as shown in Fig. BO.4 or type it directly if this is not present between in the listed values.
Fig. BO.4 – If you didn't insert the scale value when opening the map, you can do it now from the Affine transformation.
Then, to define the interval between the grid lines, just go the Grid transformation and perform the same operation from the Interval cell, as shown in Fig. BO.5.
Fig. BO.5 – If you didn't insert the grid interval value when opening the map, you can do it now from the Grid transformation.