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Post by wildbill on Feb 24, 2021 20:11:09 GMT -5
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Post by wildbill on Feb 24, 2021 20:17:34 GMT -5
I have successfully built 2 other golf courses using chads tool so I am fairly certain I have the process down. This is the first time that I have come across a missing EPSG value in the metadata. Trying various values of EPSG from spatialreference.org I just cant get the latitude and longitude correct for the OSM overlay.
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Post by wildbill on Feb 25, 2021 12:27:21 GMT -5
Well I found it. 6341 It wasn't easy. Found a technical data report prepared by the company that did the data collection. In it there was a scant mention of this EPSG number. Odd that this code does not show up on spatialreference.org/ref/?search=idahoAnyway I thought I would post how this problem got solved. Maybe it will help someone here
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mal
Amateur Golfer
Posts: 214
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Post by mal on Feb 25, 2021 12:30:24 GMT -5
You can always use lastools to look at the header data contained within the las files, and the correct EPSG code will be the one associated with the horizontal coordinates.
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Post by wildbill on Feb 25, 2021 16:52:49 GMT -5
Thanks mal! I will do this in the future if needed.
lasinfo did return header data from the .laz file that had the EPSG number 6341.
So I do have a question about Chads tool (which has been awesome BTW), if the correct number is in the header of this particular .laz file, why did the tool say that it couldn't find it in the metadata?
WKT OGC COORDINATE SYSTEM: COMPD_CS["NAD83(2011) / UTM zone 12N + NAVD88 height", PROJCS["NAD83(2011) / UTM zone 12N", GEOGCS["NAD83(2011)", DATUM["NAD83 (National Spatial Reference System 2011)", SPHEROID["GRS 1980",6378137,298.257222101, AUTHORITY["EPSG","7019"]], AUTHORITY["EPSG","1116"]], PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]], UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","6318"]], PROJECTION["Transverse_Mercator"], PARAMETER["latitude_of_origin",0], PARAMETER["central_meridian",-111], PARAMETER["scale_factor",0.9996], PARAMETER["false_easting",500000], PARAMETER["false_northing",0], UNIT["meter",1,AUTHORITY["EPSG","9001"]], AXIS["X",EAST],AXIS["Y",NORTH],AUTHORITY["EPSG","6341"]], VERT_CS["NAVD88 height", VERT_DATUM["North American Vertical Datum 1988",2005,AUTHORITY["EPSG","5103"]], UNIT["meter",1,AUTHORITY["EPSG","9001"]],AXIS["Up",UP],AUTHORITY["EPSG","5703"]]]
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mal
Amateur Golfer
Posts: 214
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Post by mal on Feb 25, 2021 18:08:46 GMT -5
The metadata would be an external xml file and these files rarely contain the needed EPSG information. Plus the tool doesn't always understand the metadata format anyway.
The tool doesn't usually pull from the header of the las file, though I have seen it successfully grab the prj coordinates on occasion. Anyway, just use lastools and you will have a 99% chance (some headers are populated with incorrect data) of getting the correct X/Y EPSG code.
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