GEOM 30009: Imaging the Environment
1. Human vision:
Describe the similarities between a camera and the human vision system. Name three components that a camera has in common with the human eye. (10 points)
2. Electromagnetic radiation:
The figure below shows the effect of atmosphere in scattering and absorption of electromagnetic radiation. What does this figure imply for imaging the earth from space? Can we use any wavelength for imaging? If necessary, give an example to clarify your answer. (10 points)
3. Imaging sensors:
Provide a comparison of airborne imaging and spaceborne imaging in terms of the following criteria: (10 points)
Coverage
Spatial resolution
Accuracy of image measurements
Cost
Flexibility for planning the time and location of image acquisition
4. Image interpretation:
Give an example on how each of the following elements is used in image interpretation. (10 points)
口 Tone
口 pattern
口 Association
口 shadow
口 site
5. Image processing:
Explain what an image histogram is (5 points), and how histogram stretching can be used to improve image contrast (5 points). Use diagrams to explain your answer.
6. Information extraction:
A useful method for segmenting an image into homogeneous regions is region growing. Explain how region growing works (5 points), and give an example of homogeneity criteria in segmentation (5 points).
7. Georeferencing and rectification:
Describe the image rectification process (4 points).
What type of distortion can be corrected by rectification (3 points)?
What assumption about terrain topography is made when rectifying an image (3 points)?
8. Orthorectification
The image below shows a mosaic of two aerial images in Google Maps with misaligned features along the cutline.
● Where is this misalignment problem more severe? why? (3 points)
● What causes the misalignment of features between the two images? (3 points)
● What process should be performed to correct for this problem? Describe the process briefly. (4 points)
9. Measuring in images:
Which of the following processes should be applied to an image before it can be used for making reliable 2D measurements? Explain your answer (10 points).
Band ratios
Orthorectification
Image segmentation
No processing is needed.
10. Measuring 3D in images:
What are the requirements for making 3D measurements in images? Explain your answer briefly. (10 points)