These are often at abrupt angles. They are artifacts that occurred when the data was first processed and are now a permanent part of the data. Images that are made of many other images are called mosaics. They often have these types of lines at the border between two images that were originally at vastly different resolutions. These mosaic lines or other dataset distortions are something MapMaker has little control over.
Bugs often manifest themselves that way.
In cases where something else unusual or unexplained happened that might or might not be a bug, report it. We would rather you report something that you are unsure about, than not. Right here . Yes, MapMaker supports several other data sets and you will be able to access these on a website we call the planetary atlas that will be finished by the end of summer. There are many places around the net.