LAB
EXERCISES FOR GOG 385, GOG 584, PLN 551
INTRODUCTION
TO REMOTE SENSING OF THE ENVIRONMENT
(revised
06/01)
The Lab Exercises are meant to
reinforce the material presented in lecture and in the text by giving you
practical applications of principles learned.
The exercises follow the lectures and text closely.
Lab Exercises will be due one week
from the day assigned unless otherwise indicated. There will be a penalty for any lab which is handed in late. You should be prepared to devote more time
to the exercises as the semester progresses.
As you gain expertise and your skills evolve, the exercises will become
more involved and explore the interrelationships of remote sensing principles.
Lab equipment for the course:
1)
Ruler
2)
Colored pencils
3)
Drafting Tape (not masking or transparent)
4)
Hand magnifier (5X or better)
5)
White lab gloves
6) Herculine,
or mylar, or tracing paper
7) Pocket
calculator
There will be a total of 8 Labs to
be completed during the semester. They
will all be of equal weight in terms of credit.
SCALE,
AREA, AND TIME OF DAY: Lab 1
The
scale of a vertical aerial photograph is a function of the focal length (F or
FL) of the camera lens and the height (H or ALT) from which the exposure is
made. Knowledge of these two factors
allows us to determine the representative fraction (RF) of an image through use
of the following equation:
Camera Focal Length
RF = Altitude Above Ground Datum
Shadows
cast by objects allow us to determine the approximate time of day in which the
image was exposed. The image must be
oriented north before determination of the time of day can be made.
After
you have completed this lab exercise you should be able to determine: RF of an
image, the area covered on the ground by an image and the approximate time of
exposure of an image.
GRADING:
Answers
to questions will be judged according to neatness, in addition to having the
correct answers. Indicate all formulas used and clearly show all work where necessary.
1) Define remote sensing.
2) Define electromagnetic spectrum.
3) a)
What are the optimum hours for exposure of aerial
photographs? Explain your
answer.
b) Do you think there would ever
be an exception to the
above
answer? If so, in what case(s)?
4) What is the difference between a
"photograph" and an "image"?
5) Altitude = 1500 meters
Focal length = 30.48 cm
Determine the RF (to the nearest whole number).
6) Altitude = 10,000 meters
Focal
length = 300 mm
Determine the RF (to the nearest whole number).
7) I, Rufus T. Firefly, am your pilot and we
are flying over a local commercial area at an altitude of 800 feet. To take pictures of the area below the
hand-held camera on board is fitted with a 6-inch focal length. What scale will our photographs have after
we get them adequately developed?
8) You are involved with a project to re-map
the area surrounding and including Mt. St. Helens, WA. You want to acquire imagery that will be
compatible (same scale) with pre-map 1980 USGS topographic sheets (7.5',
1:24,000). At what height (in feet)
will you tell the pilot to fly with a camera having a 6-inch focal length (to
the nearest foot)?
Remember: Even after the
eruption the mountain height is 8364 feet above mean sea level.
9) You've been handed a satellite image that
includes Albany, NY and told that the height of the satellite orbit was 580
miles and the focal length was 30.48 cm.
What is the RF of the image (to the nearest whole number)?
10) What
is the focal length (in cm) of a camera that produces imagery with a scale of
1:2,000 when flying at an altitude of 1000' (to the nearest hundredth cm)?
11) You,
in your capacity as a dedicated forester, are attempting to catalog all the
different tree species in a given forest tract. However, budget cuts have necessitated that you buy imagery
instead of flying it yourself. Two
aerial survey firms have the appropriate imagery, taken recently, and at the
seasonal time you need it. Firm A flew
the area at 1000 meters with a camera having a 6 inch focal length. Firm B has done the imagery from a height of
1500 feet with a 16 inch focal length.
What imagery would you choose and why?
12) Map
distance = 4 inches
Map
scale = 1:24,000
Photo distance = 2 inches
Photo scale = ? (to the nearest whole number)
13)
Photo distance = 6 inches
Photo scale = 1:48,000
Map
scale = 1:50,000
Map
distance = ? (to the nearest tenth of an inch).
14)
Scale = 1:48,000
Cell
size = 10 hectares
What
is the length of a side of a cell on this overlay (to nearest mm)?
15) If a
cell overlay is prepared for a photo at 1:24,000 and each side of a cell is
2.54 cm in length, then what is the area on the ground which is covered by the
cell (to the nearest hectare)?
16) An
overlay is prepared for a given image, with each cell representing 40 acres on
the ground. What is the scale of the
image if the length of a cell side is 0.25" (to the nearest whole number)?
17) If
an overlay is prepared for a photo at a scale of 1:10,000, where each cell
covers an area on the ground of 10 hectares, what area will each cell represent
if the overlay is then picked up and placed over a photo with a scale of 24,000
(to the nearest hectare)?
18)
Photo: 1594-863
Utilizing the dominate land use method with the grid provided, determine
the approximate area (in acres) of the lake circled at the bottom of the photo.
19)
Photo: Heck Development Center.
a) What is the ground perimeter
of the building circled at the top
of the photo in meters? In feet?
b) Assume you had not been given
the scale of the imagery in
part a), how would you have calculated it? Describe your
procedure.
20)
Photo: Glens Falls 5-57
Scale: 1:12,000
What
is the road distance on the ground, in meters, across the bridge?
***BONUS***
What do you think accounts for the darker tone of the
bridge?
21)
Photo: Port of Albany
Scale:
1:12,000
a) What is the length (distance
on the ground) of the ship
circled in the photo?
b) How long would the ship be
(distance on the photo) if the
scale was 1:24,000?
c) What is/are another word(s)
for the "optical center" of
a photograph?
22)
Photo: Schenectady
What
time of day was the photo taken? How
did you reach this conclusion?