lab4

GEOG 271 Feb 15, 2022, Winter Lab 4 1) A. Mean Min Max Standard Deviation Uncorrected Image Band 4 (NIR) 126.563 15 247 25.1818 Band 3 (Red) 55.6138 25 255 18.6735 Band 2 (Green) 60.8079 36 255 11.1395 Corrected Image Band 4 (NIR) 3904.66 463 7620 776.795 Band 3 (Red) 1147.6 1 5260 385.178 Band 2 (Green) 572.031 2 5202 265.611 B. C. Road Vegetated Area Water Uncorrected Image R: 64 G:64 B: 67 R: 149 G: 31 B:45 R:20 G:31 B:41

Corrected Image R: 1966 G: 1317 B: 725 R:4575 G: 638 B:203 R:615 G:638 B:108 2) In this kind of atmospheric correction, there are several assumptions made from the image parameters inferred from its metadata. For example, in the Sensor and image settings, the sensor information such as the Solar zenith is inferred based on the information about the satellite, Acquisition date and the solar azimuth. Another example is in Haze and cloud masking tab, the Omit choice identifies that the input image has no clouds so the cloud masking operation is skipped. In the illumination conditions tab, the base elevation (constant height) is based on a general measurement on web maps so it does not consider drastic elevation differences in small areas in the study area. From the satellite data, latitude and longitude, and collection date, the atmospheric information on the Visibility and ground reflectance tab is also auto filled to be rural and mid-latitude summer. To improve the correction procedure, information about the uncorrected image should be accurate from the data collecting standpoint rather than assumptions made from other metadata. 3) A. 3 errors: - The exact matching pixel allocation between the uncorrected and the referenced picture is difficult to b e exactly accurate (always at least a miniscule distortion) making warping of the image never perfect - The two images comes from different sources which has possible metadata differences which can distort location and status of features on the map - The resolution (pixel count) between the two images might be different therefore, warping will distort the corrected image B.

D.