AT 309 Week 14 - Geographic Referencing and Datums
This lab covered geographic referencing and datums, which we used to fix a set of bad GCP data.
We start with the concept of metadata. Why is metadata important? Metadata helps provide context to all the information that you’re working with and is extremely important to avoid confusion like what we’re dealing with above. Just knowing the physical location of where the operation was done can help me confirm the coordinate system, because then the GCPs will be at that location and not in the middle of the ocean, or Mars. The information we are given in this lab was improperly collected, so we have to do some investigative work to fix it. The data had bad altitudes as a result of using the geoid height rather than the orthometric height, so we had to use the online NGS map to find a survey marker nearby and learn what the offset is for that location.
Name | Original Height | GEOID12A Corrected Height |
Control 01 | 246.7 | 280.552 |
Control 02 | 243.69 | 277.542 |
Control 03 | 241.37 | 275.222 |
Control 09 | 249.04 | 282.892 |
Control 04 | 247.98 | 281.832 |
Control 07 | 270.51 | 304.362 |
Control 00 | 280.1 | 313.952 |
Control 06 | 280.58 | 314.432 |
Control 05 | 271.96 | 305.812 |
Control 08 | 266.98 | 300.832 |
Flag 3 | 263.61 | 297.462 |
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