4.12.2. Measurements by Parallax Bar

Try these first

1. 1.

   What is parallax?

   Hint

   Think about how you see objects differently from various viewpoints.

2. 2.

   What does a parallax bar measure?

   Hint

   Consider how we calculate elevation based on seen images.

3. 3.

   What does the parallax bar measure?

   • The height of objects
   • The distance from the camera
   • The difference in parallax between two points

   Hint

   Think about what the device is specifically designed to do.

4. 4.

   True or False: Higher points have less parallax than lower points.

   • True
   • False

   Hint

   Recall the relationship between height and observed displacement.

5. 5.

   A stereo pair photograph shows a known control tower height of 200 meters. If the parallax readings indicate a difference of 5 mm for a new building, what is the estimated height of the building?

   Hint

   Use the established relationships and examine similarities to find the new height.

6. 6.

   You measure a parallax of 2 mm for a low hill. If the corresponding known elevation for the reference point is 80 meters, how would you calculate the approximate height of that hill?

   Hint

   Think about how minor changes in parallax help us calculate differences in height.