Lab 8: Photogammetry

 Shelby Short

Goal and Background:

The goal of this lab was to perform key photogrammetric skills on vertical aerial photographs and by extension satellite images. By doing this, we will understand that mathematics behind the calculation of photographic scales, measurement of areas and perimeters of features, calculating relief displacement, and performing orthorectification on a block of vertical aerial photographs. After completion of this lab, we will be able to perform diverse photogrammetric tasks.

Part 1: Scales, measurements, and relief displacement

The first section of this lab we calculated the scale of nearly vertical aerial photographs. This involves a combination of simple addition and subtraction along with unit changes to create a 1 to something scale. 

The second part of this section we looked at measuring the areas of features on different photographs. In order to do this, we opened our image in ERDAS and used the measure tool(Figure 1).  

Figure 1: Here we used the measure tool to make a polygon of the lagoon to gather the perimeter and area. 

Now, we will visually estimate and then calculate relief displacement. Relief Displacement is noticeable in an image if a vertical feature is displayed to be tilting(Figure 2). 

        Figure 2: Shows relief displacement in the left image of a smoke stack on campus.