Maps sizes are dependant on the original file / pixel dimensions of the image.
Typical setup and recommendation per manual recommendations.
" Maps are added using Map Sets Management. The map files should be .jpeg type files.
The optimal map size is 980 x 735 pixels. "
This map size is very small and would not scale up to fill a monitor.
To setup a Map to fill a monitor screen note the following.
As long the image resolution used for the map, matches the monitor resolution set for the map in the VMDC setup (VMDC Configuration) / in windows the map show on the full screen.
e.g. if my jpeg image resolution was 1024x768 and the monitor set for the map in windows or through VMDC was set to 1024x768 once I opened the Map and hit the “show full screen” icon I could get it to show on all the monitor window size. could be some difference with several pixels.
Testing with several resolutions , matching the jpeg slight deviations 99.5 % of monitor was covered.
Maps setup ( see complete details in Software manuals)
( note this link may change )
Monitor setup for Maps
Monitor showing full screen map - this example is a 1920x 1080 map and monitor