How To Write Up Calculations
For Full Credit In Aerial Photography and Remote
Sensing
(and to avoid embarrassing and
expensive errors anytime you make a calculation)
1. Write down the equation that you
need to solve the problem
RF = f/H
If you need to reformulate the equation for the problem at
hand, show what you did. For example if
you know that scale and the focal length and are trying to find the flying
height write
RF = f/H
H * RF = f
H = f/RF
2. Write down the actual measurements
you make on images or maps. Label the number with a description and units. If the measurement is one of the variables in
the equation, include that in the description
d = parallax displacement, 0.2 in from base of building to
top
or
235 dots in urban areas
3. Write down any additional
information you will use, with units and source
H = 3000 ft flying height, given on photo
RF = 1:3500 calculated last week
4. If you have to make a calculation to
derive a variable, show the steps
dP = distance between bases – distance between tops
= 2.35 in - 2.21
in = 0.14 in
5.
Write
out the equation with all your numbers and their units
RF = 6 in/20,000 ft
or 0.5 ft/20,000 ft
6.
If
you need to do unit conversions at any point, show your steps and the
cancellation of units.
h = 24 in. * 1 ft/12 in. = 2 ft
7. Write your answer in it’s final
form, with units. And check to see that
it is reasonable! We are measuring real
objects. If you have a house that is 300
ft tall, or a lake that is 100 sq. ft.
something is wrong in your measurements or calculations.
8. If you are doing the same
calculation several times in the same problem or on the assignment, you can
take some shortcuts in the above, but always show any new basic raw
measurements and give a reference to the complete description.
in the same way, with d = 0.3 in. and r= 4 in.
h of building 2 = 0.3 in / 4 in * 3000 ft
or
as in 3. above with d = 0.3 in …..
9. Be careful with equals signs. 4/5 =
8/x = 10 is not correct. Use arrows to
show that one calculation or equation leads to another 4/5=8/x
→ x=10.