Perspectives: A Comparison of Map Views

On this page, you'll find some neat perspectives that can be obtained from a single map with elevation data. All views on this page use the same base map, the USGS quadrangle of the Grand Canyon of the Yellowstone. However, each image has a different way of displaying the map. Even when you start with the same map, not all maps are made the same!

This first map is fairly straightforward -- it's a digital representation of a section of the Canyon Village paper map. You can find features on it just like you would on the real map, and read contour lines to find elevations. Image size has been reduced somewhat for web viewing.

To make things more interesting, we'll add in some elevation. By using 3-D imaging software, it is possible to create a heightfield from elevation data and view the above map on top of that. This technique has the advantage of showing relief much better than contour lines ever could and adding a real sense of depth to the flat topographic map.

The above map looks really good, but you can find flaws if you look closely. Notice how the otherwise-straight UTM lines get skewed as they go into the canyon. Also notice how the text curves unnaturally, as if it were plastered to the canyon wall. This is not a bad view, it just needs to be understood in context. Imagine if you were to fly over this area at several thousand feet of altitude, then to point a camera straight down and take a picture. Because of photographic limitations, distortions will be present in the photo; areas at the edges will especially be affected. The photo couldn't be used very well as a map, since it would not have straight grid lines or constant scale. The same distortions are present in the image above, since it uses a perspective view much like a camera's.

This image should clear the previous one up a bit. This is an orthographic view that uses parallel camera rays to create a distortion-free image. Lines and text all retain their shape and look just as they do on the paper map, but the relief in the image is preserved. This map could be used for compass navigation, while the previous one could lead to serious navigation errors.

The previous images have all been essentially 2-D maps, even though some had 3-D elements to them. This oblique view really shows off the power of perspective. This is a sort of aerial view of the Canyon area from the south using a nice 3-D perspective.