WETMAAP Skill 2
Cocodrie Element 2 

Skill 2:  Scale Determination
Element 2: Determining Scale of 1995 Aerial Photograph

Materials:

        1994 1:24,000 scale Lake Quitman-Cocodrie Topographic Quadrangle 

        1995 Aerial Photograph of study site

        9" x 9" clear film overlay

        color marker pens

        ultra fine black marker pen

        ruler     

        drafting tape

        calculator    

        Reference Manual 

Exercise:

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

        3. Using the 1:24,000 scale topographic map and the Black pen, locate the four corners of the study site on the 1995 aerial photography. 

        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: It is best to identify and use cultural features, but if not enough are available, use two natural feature points that do not appear to have changed. 

        6. Identify the exact same two features from the topographic map on the 1995 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 1995 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?