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A digital aerial photo with dimensions 4000 x 3000 was captured using a camera with a 7 micrometre (7 x 10-6 m) pixel size and a 35mm focal length at a flying height of 700m. Assuming the image was taken directly downwards, calculate the expected ground coverage (extent) of the image. Show all your calculations.
Explain the concept of bundle adjustment as a photogrammetric technique.
Name four elements associated with visual image interpretation.
Photogrammetry is, in its essence, a relationship between the camera or sensor, the image, and the ground. Briefly explain how this relationship is defined using interior and exterior orientation parameters.
a) What does orthorectification do? (4)
b) What is a ground control point (GCP)? (2)
c) What is the function of a stereo GCP? (2)
d) List two sources of GCPs (i.e. what can be used to collect the XYZ coordinates of GCPs) (2)
e) Under which circumstances can orthorectification be done without GCPs? (2)
Aerial photogrammetry involves a series of transformations to convert 2D image measurements into real-world ground coordinates.
a) Name the four main coordinate systems used in this process. For each, specify the typical units and what the origin represents. (8)
b) Summarise the steps to convert scanned photo pixel coordinates to ground coordinates. (4)
c) Explain the key difference in the implementation of this workflow when applied to digital aerial imagery (DAI) compared to digital derived image (DDI, also referred to as an analogue image). (3)