GEOG 3420- Midterm Exam Guide - Comprehensive Notes for the exam ( 15 pages long!)
11 Oct 2017
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Document Summary
Whiskbroom scanners: ground swath is slightly skewed due to forward movement of the platform during time required for scan line to be recorded. Zigzag pattern creates areas that are not imaged or overlapped. Pushbroom scanners: always capture an entire row at a time. Earth rotates on its axis (east to west) as sensor scans the terrain. Each sweep is slightly to the west of the previous one. Ground crew deals with correction to image. Mirror scanning rate may vary producing along-scan geometric distortion. Faster= larger area of ground = changes in velocity = effects on pixel size. Due to variation in ground area being sensed, from nadir to edge of the scan line. Same area is going to take up a larger physical sense along the edges. Each pixel in the image display is the same size, but encodes an increasingly larger ground area away from the nadir line (looks crushed) Result: image will appear compressed towards the edges.
