The program 3DField can overlay a contour map on bitmap base map. One can generate a list of bmp-files from which to choose a background. Base maps can be combined with contour map and scaled together.

The “Objects - > Base Map” menu opens the dialog.

The “Add” button adds a file in the list. The list can contain positions in the same file, but at other location on a map. “Delete” removes a selected line from the list. “Visible” places or deletes the background image from a map. “Set as Default” automatically places the image on a new map. “Rename” gives a position a new name.

The background can be stretched to a full window, placed at the center or adhered to two coordinate points with the “Assigning Coordinates” button.