Advanced Photography Course

144,000/12 = 12,000 feet

2. Determine the ground coverage. Now that

you know the altitude at which the mission must be
flown to obtain a scale of 1/12,000, you can determine
the amount of ground coverage on each frame. Again,
this information can be determined using the IFGA
formula. Remember that the forward overlap required
is 60 percent. The remaining 40 percent of the 9-inch
negative is usable imagery for GGF. You must first find
the size of the usable portion of the negative for GGF.
This is accomplished as follows:

0.40

9 = 3.6 inches of useable image area for GGF

I = G so G = IA

=3.6×

12,000 =3,600 feet

The amount of side lap required is 40 percent. This

leaves only 60 percent of the useable negative image
area for GGS. You determine the usable portion of the
negative for GGS as follows:

0.60

9 = 5.4 inches of usable image area for GGS

G= 5.4

12,000

=5,400 feet

3. Determine the total number of frames

required.

Next, you need to determine the total number

of frames required to complete the mission. You know
that the area to be mapped is 10 nautical miles east and

west by 20 nautical miles north and south. Therefore,
the strips will be flown north and south.

The number of exposures per strip is determined by

dividing the GGF into the length of the map. First
convert nautical miles into feet (1 nmi = 6,080 ft) and

multiply by 20 (length of area to be mapped).

6,080

20 = 121,600 feet

Next, divide by the GGF as follows: 121,600/3600

= 33.77 or 34 frames per strip. Remember to add four
more frames. This totals 38 frames for each strip.

Now you must find the number of strips required.

The area to be mapped is 10 nautical miles long.
Calculate the number of strips as follows:

10 (nautical miles)

6,080 (feet per nautical mile)

= 60,800 feet

60,800/5400 (GGS) = 11.25 or 12 flight strips

Remember to add one strip, so a total of 13 flight

strips is required.

To determine the total frames required for the

mapping mission, you must multiply the number of
frames required for GGF by the number of flight strips
required as follows:

38 = 494 frames

4. Draw flight lines on the chart. Your next step

is to draw the flight lines on the chart used to fly the
mission. The scale of this chart is 1/50,000.

To determine the distance between the plotted lines

on the chart, you must convert the GGS into inches, and
then multiply the GGS (in inches) by the scale of the
chart as follows:

5,400 (feet)

12 = 64,800 (inches)

1/50,000 =

1.29 inches

The distance between flight lines on the chart is 1.29
inches apart. A multi-finger divider should be used to
draw these lines.

5. Determine the time interval between exposures.

To determine the exposure interval, first convert the
aircraft speed to feet per second. The true aircraft speed
is operating at 140 knots, but there is a wind of 15 knots
coming from the north. Since the aircraft will be flying
in a north and south direction, the wind factor must be
taken into consideration. At this time determine the
corrected airspeed in knots, then determine the airspeed
in feet per second as follows:

1. Corrected airspeed.

a. Aircraft flying toward the north

Corrected airspeed (140 knots - 15 knots = 125

knots)

b. Aircraft flying toward the south

Corrected airspeed (140 knots + 15 knots = 155

knots)

2. To determine aircraft speed in feet per second,

you must multiply the corrected airspeed by the

conversion factor of 1.7.

a. Aircraft flying toward the north = 212.5 feet

per second

b. Aircraft flying toward the south = 263.5 feet

per second

To calculate the exposure interval, you must use the

following formula:

T= D

4-25

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Advanced Photography Course

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DOFMaster for Windows On-line Depth of Field Calculator DOFMaster for Mobile Devices On-line Depth of Field Table Hyperfocal Distance Chart Articles FAQ Recommended Books Support Contact Links Home As an Amazon Associate I earn from qualifying purchases.	contents <- previous page next page -> 144,000/12 = 12,000 feet 2. Determine the ground coverage. Now that you know the altitude at which the mission must be flown to obtain a scale of 1/12,000, you can determine the amount of ground coverage on each frame. Again, this information can be determined using the IFGA formula. Remember that the forward overlap required is 60 percent. The remaining 40 percent of the 9-inch negative is usable imagery for GGF. You must first find the size of the usable portion of the negative for GGF. This is accomplished as follows: 0.40 × 9 = 3.6 inches of useable image area for GGF I = G so G = IA F A F G =3.6× 12,000 =3,600 feet 12 The amount of side lap required is 40 percent. This leaves only 60 percent of the useable negative image area for GGS. You determine the usable portion of the negative for GGS as follows: 0.60 × 9 = 5.4 inches of usable image area for GGS G= 5.4 × 12,000 12 =5,400 feet 3. Determine the total number of frames required. Next, you need to determine the total number of frames required to complete the mission. You know that the area to be mapped is 10 nautical miles east and west by 20 nautical miles north and south. Therefore, the strips will be flown north and south. The number of exposures per strip is determined by dividing the GGF into the length of the map. First convert nautical miles into feet (1 nmi = 6,080 ft) and multiply by 20 (length of area to be mapped). 6,080 × 20 = 121,600 feet Next, divide by the GGF as follows: 121,600/3600 = 33.77 or 34 frames per strip. Remember to add four more frames. This totals 38 frames for each strip. Now you must find the number of strips required. The area to be mapped is 10 nautical miles long. Calculate the number of strips as follows: 10 (nautical miles) × 6,080 (feet per nautical mile) = 60,800 feet 60,800/5400 (GGS) = 11.25 or 12 flight strips Remember to add one strip, so a total of 13 flight strips is required. To determine the total frames required for the mapping mission, you must multiply the number of frames required for GGF by the number of flight strips required as follows: 13 × 38 = 494 frames 4. Draw flight lines on the chart. Your next step is to draw the flight lines on the chart used to fly the mission. The scale of this chart is 1/50,000. To determine the distance between the plotted lines on the chart, you must convert the GGS into inches, and then multiply the GGS (in inches) by the scale of the chart as follows: 5,400 (feet) × 12 = 64,800 (inches) × 1/50,000 = 1.29 inches The distance between flight lines on the chart is 1.29 inches apart. A multi-finger divider should be used to draw these lines. 5. Determine the time interval between exposures. To determine the exposure interval, first convert the aircraft speed to feet per second. The true aircraft speed is operating at 140 knots, but there is a wind of 15 knots coming from the north. Since the aircraft will be flying in a north and south direction, the wind factor must be taken into consideration. At this time determine the corrected airspeed in knots, then determine the airspeed in feet per second as follows: 1. Corrected airspeed. a. Aircraft flying toward the north Corrected airspeed (140 knots - 15 knots = 125 knots) b. Aircraft flying toward the south Corrected airspeed (140 knots + 15 knots = 155 knots) 2. To determine aircraft speed in feet per second, you must multiply the corrected airspeed by the conversion factor of 1.7. a. Aircraft flying toward the north = 212.5 feet per second b. Aircraft flying toward the south = 263.5 feet per second To calculate the exposure interval, you must use the following formula: T= D S 4-25 contents Advanced Photography Course <- previous page next page ->	As an Amazon Associate I earn from qualifying purchases.
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