18
Determining Number of Photos
For spot photography, take multiple photos as appropriate. More are better than less!
For route photography and aerial mapping, one must determine the length of each leg.
Using a map, determine each leg length in statute miles. Multiply the leg length in statute
miles by 5280 feet per mile. Divide that number by the length of each photo less the
photo overlap (see "Selecting a Time Interval" above). The result is the number of photos
that need to be taken during the leg. Program the Multi Function Timer Remote Control
with the result. For example, for a leg length of 8 miles and a 25% overlap of photos with
each photo 800 feet wide, 5280x8=42,240. (100%-25%) x 800 feet = 600 feet.
42,240/600 = 70 photos.
2.3 Planning the Flight Path
A spot photography mission requires that the target-center be accurately located and that
the flight pattern to be flown around the target be defined. This will require accurate
determination of waypoints which are defined by their latitude and longitude. Those
numbers will be used by the flight crew to program the aircraft GPS accordingly.
An aircraft sectional map can be used to determine the numbers. All qualified flight crew
members know how to do so.
An alternative is to use a computer-based mapping program such as DeLorme Street
Atlas or Google Earth. In both cases, make sure the latitude and longitude values are set
to display degrees, minutes and fractional minutes (D M.M) and not degrees, minutes and
seconds.
DeLorme Street Atlas has the advantage that it is self contained on a computer and does
not require an Internet connection to work. Google Earth is a better alternative where a
Web connection is available.
DeLorme Street Atlas is not included in the D90 kit. It is a local-purchase item;
Squadrons may elect to use other computer tools to determine waypoint information.
The following is a snapshot of a Street Atlas map:
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