4.12. Determination of Height from Vertical Aerial Photographs

Try these first

1. 1.

   What is a stereo-pair?

   Hint

   Think about how we perceive depth using two eyes.

2. 2.

   Define parallax.

   Hint

   Consider how you see objects from different positions.

3. 3.

   What is the primary purpose of using a parallax bar in aerial photography?

   • To measure distances
   • To determine parallax differences
   • To enhance image quality

   Hint

   Think about what it measures during the stereo image process.

4. 4.

   True or False: A higher elevation results in a smaller parallax measurement.

   • True
   • False

   Hint

   Consider the relationship between height and parallax.

5. 5.

   Given a known control point with an elevation of 100m, you measure a parallax difference of 8 mm at two points. Calculate the estimated height of the unknown point using heights and parallax relations.

   Hint

   Look closely at the formula relating height and parallax before plugging values in!

6. 6.

   If a photographer captures stereo-pairs with a tilt that you suspect may influence parallax measurements, outline how you can mitigate these errors.

   Hint

   What adjustments could you make to account for tilt in your measurements?