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12 Cards in this Set
- Front
- Back
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Aerial Triangultion |
process of piecing together overlapping aerial images so to make a map determine position of each image in a mapping frame with ground control points |
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Auto Correlation |
mathematically computing common features found in 2 or more pictures captured from different perspectives |
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How does Auto Correlation work |
Interest points with 2 overlapping photos, identify points based on invariability in translation, rotation, scale, reduce points mathemetically to the ones with the least variability |
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Orthophoto |
Rectified or Straightened |
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What are the required inputs for Orthophotos? |
- Digital Air photo - DEM (maybe DSM if making a True Ortho) - Output scale (pixel size) |
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How are displacements and distortions dealt with in orthophotos? |
- Camera Calibration (earth curvature, atmospheric refraction) - Photogrammetric orientations (tilt/tip) - Orthorectification (terrain/radial distortions) |
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Which resampling prodecures produce an orthophoto from an air photo? |
Geometric resampling Spectral resampling |
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Production problems of the image quality of ortho rectification |
colour matching/balancing radiometric correction feathering pixel size (too coarse) |
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Production problems of the positional accuracy of ortho rectification |
quality of external orientations ground control points DEM and mosaicking procedure |
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Standard Orthos |
DTM DEM Corrects ground elevations (fields, mtns, forests) |
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True Orthos |
DSM Corrects elevated features (buildings, trees) |
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What is the purpose of an orthophoto? |
gives visual details of an air photo and the usefulness of a map Photo Maps |
