We have all visited websites like “MapQuest” and “Google Earth” and enjoyed scrolling through the many satellite maps and images that they make available. When we choose to view these images in their “hybrid” mode we often see street names, landmarks, bodies of water, and other details set over the satellite view of the region.
These maps are wildly popular, and offer a good example of the capability of modern mapping programs using GIS technologies. Whether or not they are created through such software is difficult to say, but their results are similar (if less accurate) than what true GIS can do.
It helps to understand that GIS is the same technology put to work by the USGS among other groups, and it is relied upon to create pinpoint, accurate visual representations of complex data sets. It is important to understand that a group like the USGS doesn’t just request an aerial photograph of a city or mountain range, and then line up their one-dimensional map on top of this. Instead they take every type of field data they can find, including elevation measurements, slope details, and satellite maps and input them into a mapping program. From there the software performs highly complex analysis, comparisons and adjustments in order to yield the kind of maps released through the USGS.
Do they really need satellite maps? Absolutely, and this is due to the fact that they often provide documents about areas with little to no inhabitation. This means that if the vast slope of a mountain collapses, or if the course of an ancient riverbed changes and shifts, it is only through up to date satellite maps that they will get this information.
Another issue that must be addressed in any discussion of satellite maps and GIS technologies is the need for color adjustments and appropriate blending. While satellites can photograph vast areas of land, they cannot do so with precision. This means any program using them for mapping should also incorporate a graphical/editorial component too.