Remote Sensing: Lab 7

In lab 7 we first calculated scales and distances of photographs that were nearly vertical when taken. The first exercise was to measure the distance between two points with a ruler. The image below was used.

Notice points A and B in upper left corner.

I had to physically take a ruler and measure the distance between point A and B. The distance came out to be 2 11/16 inches. Each inch indicates 3000 feet, so the distance came out to be 8062.5'. The distance was also recorded by a surveyor of 8822.47', take with a engineer's chain. So my distance came within 800'.

Second part was to calculate the scale of a photo. The phot was described as being taken 20,000 feet above sea level with a camera that had a focal length of 152mm. Formula for this is

f= Focal Length
H= Altitude of photo
h= Elevation of terrain

My calculations came out to be 1/38408 scale.

Next we took calculation of an given area in an image. We were to calculate the area of a lagoon in the image below.

We first had to digitize the lagoon, then the area was calculated.
Area
37.8128 Hectares
93.43759041069 Acres
Perimeter
4151.55 Meters
2.579653 Miles

Relief displacement was next. Using the image below we calculated the relief displacement of the smoke stack.

d = (h x r)/H

d = relief displacement.
h = height of object (real world).
r = radial distance of top of displaced object from principal point (photo).
H = height of camera above local datum.
h= 7/16"
r= 31,125'
H= 3980
All comes out to be 10264.21168 relief displacement.

Stereoscopy is process that creates an illusion of depth to an image. We took two images and combined them using GCP's to form an image with 3D illusion.
Here is the final image.

With the use of polariod glasses slight elevation changes can be seen. The areas that show the most elevation changes are in wooded areas.

The last part of the lab was Orthorectification. With the use of GCP's we combined multiple images.