I am brand new to Repast and am interested in eventually creating a marine traffic simulation in the Arctic. I am going through the "Import Repast Examples" and none of the models I go through display the maps in the simulation display. For example this shot of the Geotracks demo shows the blue marble map is clearly not loading. 
In the Geography demo a small thumbnail of Chicago is visible but none of the surrounding map. 
I couldn't find any documentation to fix this issue. When I go to the GIS display setup it appears the files are enabled so I do not known what else to do to troubleshoot.

Here is a picture of the console errors that I am receiving.

I installed Repast using the default installation settings for Windows.
I am able to replicate the issue. The background map layers are provided by the NASA WorldWind service and it appears that the servers are sometimes slow or unresponsive. This data is served by third parties and the Repast team does not have direct control over providing the background map layers. There does appear to be a solution as posted by one of their developers here: https://github.com/NASAWorldWind/WorldWindJava/issues/219 in which they describe how to improve some of the WorldWind network properties to help with the slow servers, and I have tested that this does work.
You will need to copy the below into a file named "worldwind.xml" in your project:
For testing with the Repast Geography demo, I placed the worldwind.xml file in the geograph.styles folder. And then in the ContextCreator.java add the following:
This will tell WorldWind where to find the modified worldwind.xml file. You will need to repeat this process for any other Repast model that uses the background NASA layers. Apologies for this clunky workaround. We will fix this in the next Repast release so that you don't need to manually perform these changes.