Selections available via the Main Menu and the subsequent functions or sub-menus are described below:
redisplays the raster map layer on the graphics monitor.
calls the d.zoom program, to allow changing the view of the raster layer. Zoom's instructions will appear on the text command window. Interaction is conducted using mouse keys.
This function is available for users editing aspect maps. The d.rast.arrow program is called, which draws arrows over the displayed cells to indicate the downslope direction of the cell. After selecting the arrow selection from the main menu, sub-menus will appear, allowing input options to be set for the d.rast.arrow program. The first sub-menu selects the type of aspect data displayed. (regular "GRASS" format, as produced by r.slope.aspect ; a format prepared as input to the "AGNPS" program; and a format prepared for the "ANSWERS" program. The d.rast.arrow program can accept the name of a layer not drawn on the display for use as input, and an option is given to input the name of that layer, if desired. Otherwise, the currently displayed map layer will be used. Next, the color options of d.rast.arrow may be set via separate menus, or a choice for using default settings may be used.
calls the d.rast.num program, which will print the cell category values over the displayed cells on the graphic monitor.
quit the d.rast.edit program. If edits have been made, the new raster map layer will be created. Support files are constructed. Category labels and color maps (if any) are copied from the original layer. d.rast.edit redisplays the original raster map file on the monitor as it exits.
Be careful not to cover the graphics monitor window with another frame during the editing process. In some cases, the redraw option will be able to remove traces of other frames; otherwise, the graphics monitor will not be refreshed until after d.rast.edit exits. Further note, however, that this has only been tested on SUN workstations, using a modified SUNVIEW graphics monitor driver.
The primary bane of the d.rast.edit program involves large map layers (with lots of rows and columns) and/or slow computers, since the program must read and write raster map layers row by row for the full size of the map layer as dictated by its region size and resolution. (The current region settings of north, south, east, and west will not limit the size of the edited copy of the map layer, since by use of the d.zoom program, these values may change several times during the editing session). Their effects could be lessened if the program were to create a table of changes that it could incorporate into the new raster file on a forked process started when the user exits, or otherwise allow the user to issue a "save" command when he has made all desired edits to the raster file. Currently, for instance, if the user needs to use d.zoom to access a different area of the map, he must wait for a read and write for each entrance and egress of the edit mode.
There is no "undo" command or way to exit edit mode without saving changes.
It would be nice to incorporate a scrollable version of d.legend (such that one could see a legend for files with many categories on a standard size sub-frame). It would be even nicer to be able to select the category values from a graphical legend when editing cell values (thereby saving a trip to the text frame to type in the new value).
Perhaps method(s) for multiple or mass cell edits would be useful. This could be done by providing modes in which the user may: 1) edit a block of cells to a given value by drawing a box; 2) be able to choose a given value which is automatically used as the new value on each cell chosen until a different value is desired.
There is no interrupt handling. This could leave files in .tmp or (rarely) result in half-baked raster files. The original file would survive unscathed by an interrupt at most any point in execution, but the graphics monitor may be left in an indeterminate state (try d.erase or d.mon select=monitor_name to bring it back into shape). Beware of exiting the program by means other than using exit on the Main Menu.
The program has no method to enter new values beyond the current range of categories, but additional programming could make it so.