WETMAAP Skill 2
Mobile Bay: Fresh Water Inflow Element 2

Skill 2: Scale Determination
Element 2: Determining the Scale of the 1996 Aerial Photograph

Materials:

1:24,000 scale topographic map
1996 Aerial Photograph of study site
9" x 9" clear film overlay
color pens
ruler
drafting tape
calculator
Reference Manual

Exercise:

1. Tape the 9" x 9" clear film overlay on top of the 1996 aerial photograph

2. Use the black pen to make four marks on each fiducial.

Hint: The fiducial is a yellow dot or cross-hair along each of the four sides of the aerial photograph.

3. Using the 1:24,000 scale topographic map and the black pen, locate the four corners of the study site.

4. Use the ruler and the black pen; link the four corners of the study site to make a complete boundary.

5. Identify two points on the 1:24,000 scale topographic map at least four inches apart.

Hint: Identify and use cultural features.

6. Identify the exact same cultural feature from the topographic map on the 1996 aerial photograph. Make a mark on the aerial photograph for each location.

7. Measure the distance between the two points on the 1:24,000 scale topographic map with the ruler.

What is the distance in inches?

8. Measure the distance between the two points on the 1996 aerial photograph with the ruler.

What is the distance in inches?

9. Using the calculator and "Scale Determination" section of the Reference Manual, determine the scale of the aerial photograph.

What is the scale that you calculated?