Aerial Image Maps Save Lives

By: Reggie Andersen

We normally tell people that a map is a representation of the surface of the Earth. This is true, but it is a stylized representation of normal conditions.

Aerial imagery shows the truth, but only for a specific segment of time, which may or may not be normal conditions, and may or may not be current. I've spent two decades in a job requiring work in poorly mapped territory, and I've found the synergistic effects of having both a map and aerial imagery is unbeatable. Whether you find yourself working in an area never effectively mapped or around your own neighborhood, there are advantages to having overhead imagery available.

For instance, overhead imagery is very helpful to contractors creating new housing developments to show details not on the maps. If resources and time permits, pictures of the same area over the course of a year can show a typical range for an intermittent stream so you can gauge its normal behavior, how much seasonal variation there is for the foliage and even occasionally the prevalence of off-road vehicular travel in an area.

Maps are excellent, but the difficulty of creating the map ensures they are done periodically at best. This means it isn't unusual to find roads are present where the map says there are none, or perhaps a road leading to a closed mine has been let go and is not really trafficable anymore. Aerial maps can provide important clues to prevent this from being a surprise. With far less effort than creating a conventional map, overhead imagery can show you the current state of the ground.

For example, in some parts of the world, neighborhoods can spring up much more rapidly than the area can be mapped. I also remember a time when I discovered the map showed a road exactly where it was, but the ridge the road was on according to the map wasn't where the map said. An aerial map would have turned that miserable morning into an easy task.

Yet the aerial map isn't a sure solution by itself. Trails that may be on the map can be nothing but treetops on overhead imagery. An uncharacteristic condition, such as flooding or a drought, can produce aerial maps that can mislead you as to normal conditions. It is also easy to misinterpret imagery if you are inexperienced. The angle of the image can turn an apparently gentle slope into something foreboding, or vice versa.

In a perfect world you will always want imagery, a map and a GPS. While on a trip overseas, I found a place where the sign said the city name was something, the population on one side of the city insisted it was something different, the other side of the city had a third choice while the map showed something else, as well as cities with all three of the other names in the same region. Having overhead imagery to compare to the city was regrettably helpful in determining where I actually was.

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