SFR 406 Remote Sensing, Image Interpretation, and Forest Mapping Jan. 22, 2015
Assignment #2 Work Problems – photo scale
Work Problems from Paine and Kiser, 2012,page 84-85
6. What are two major reasons for scale changes within a single photo?
7. Calculate the average RF and equivalent scale in terms of inches per mile if the plane flew at 11,290 feet above MSL using an 8 1/4 inch lens camera and an ave. ground elev. of 400 feet.
8. What would the average PSR of one of the photos in the previous problem be if the average elev. Of the area photographed is 750 feet?
9. What would be the average PSR between two points that are 53.6 mm apart on the photo and 32.64 chains apart on the ground? (1 inch = 25.4 mm, 1 chain = 66 feet)
11. Calculate the average RF between two points if the photo distance is 170.7 mm and the map distance is 1.68 inches and the map equivalent scale is 1 inch equals 4 miles.
12. Assuming everything remains constant except the variable listed, state what happens to the photo distance (increases or decreases):
(a) Ground distance increases ______
(b) Numerical value of PSR increases ______
(c) Focal length increases ______
(d) The flying height above MSL decreases ______
(e) The average ground elevation increases ______
13. At what elevation above sea level must a plane fly to photograph at a PSR of 10,000 if the average ground elevation is 4125 feet and the camera lens focal length is 209.55 mm?
14. Which method of determining PSR is the least expensive? Why?
Work problems from Paine and Kiser, 2014, page 43
2. Fill in the blanks or select (circle) the correct word or words in the brackets:
(a) The focal length of a camera lens is the distance between the ______and ______when focused at infinity.
(b) The ______axis of a single aerial photo passes through the (corner, side) fiducial marks that most nearly parallel the line of flight.
(c) On a slightly tilted aerial photo (>3 degrees), the (nadir, principal point, isocenter) is farther from the intersection of the x and y axes.
(d) As the focal length of a lens increases, the angle of coverage (increases, decreases).
(e) Topographic displacement varies (directly, indirectly) with the height of the object and (directly, indirectly) with the ______distance from the (principal point, nadir, isocenter).
(f) Displacement (alters, does not alter) the perspective characteristic of an aerial photograph.
(g) A (ratioed, rectified) print has had its scale altered to bring it in line with the average scale of other photos taken in the same photo mission.
3. The distance from the nadir to the base of a building is 3.42 in. and to the top of the same building is 3.60 in. The flying height above MSL was 11,400 feet and the ground elevation of the base of the building is 1400 feet. Calculate the height of the building.