Two different modern methods of map making include compilations of already existing material, and satellite or other aerial imaging. Compilation maps often try to capture a larger picture and must omit smaller details, largely due to discrepancies between existing material, while satellites and aerial imaging can focus on the minute details because they are original map creations.
Compilation maps go through extensive selection processes for selecting material, creating both problems when there are discrepancies, as well as insight into changing geographies or perceptions. This method has the benefit, however, of being able to use maps with many different purposes to draw a larger picture. For example, soil maps, geologic maps and other thematic maps can all be compared to develop a final product.
Maps created from aerial imaging and satellites encounter other problems, such as a ridge of a mountain being seen in more detail on one side than another. If the terrain is too steep, one side of a mountain may not be seen at all. This problem is rectified by either compiling many aerial or satellite images, or comparing with already existing maps. However, technology for map making is constantly advancing, minimizing the possibility of error. A person who creates maps in this way is called a photogrammetrist.