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Discussion: State Plane feet in OCAD

in: Orienteering; General;

Feb 3, 2012 6:28 PM # 
guskov:
I am working with a LiDAR dataset which uses feet in state plane coordinates, extracting contours in OL-Laser, and importing them into OCAD. OCAD only seems to have state plane coordinates in meters, how do I deal with this inside OCAD, short of converting everything to meters earlier in the process?
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Feb 3, 2012 6:40 PM # 
Tundra/Desert:
Try importing as if they were meters, then "Stretch map" and then reset the real-world offset manually... perhaps not the best way but it should work. You'll preserve the state-plane north, which is a lot of help.
Feb 3, 2012 6:41 PM # 
JanetT:
The O-maps YahooGroup might have an answer:

http://groups.yahoo.com/group/O-map/
Feb 3, 2012 6:53 PM # 
Tundra/Desert:
Oh yes, a better way... reproject your raw .LAS into UTM right away. Google LAStools. Something like las2las -sp83 MI_S -survey_feet -elevation_surveyfeet -target_utm 17T -i %1.las -o %1_UTM.las (check your state plane designator and UTM zone!)
Feb 3, 2012 8:48 PM # 
guskov:
Sweet, las2las should work. Thanks!
Feb 4, 2012 12:01 PM # 
guskov:
For the record, this worked just fine:
las2las -target_utm 16T -sp83 MI_S -feet -elevation_feet -i input.las -o output.las

Thanks again.
Feb 4, 2012 3:17 PM # 
Tundra/Desert:
-survey_feet is somewhat important. If your coordinates' abs. value is large, and you have high-res orthophotos, you may have an annoying offset for your lidar vs. orthophotos of a meter or several. Nothing that "Move Map" in OCAD wouldn't solve, but one shouldn't ever resort to that when using properly georeferenced source data.

U.S. survey foot versus international foot
Feb 4, 2012 4:24 PM # 
guskov:
Ah, but I think the data uses international feet, lasinfo and accompanying xml both say
NAD_1983_StatePlane_Michigan_South_FIPS_2113_Feet_Intl
Feb 4, 2012 4:32 PM # 
Tundra/Desert:
Good catch. That's a surprise to me, I haven't seen lidar in international feet, but then I've only looked at data in California. Everything is in survey feet in California.
Feb 7, 2012 12:17 AM # 
guskov:
Very educational about survey feet though, for sure. Thanks!

It looks like lastools support xyz format now, anybody tried getting those XYZs directly into OCAD bypassing OL-Laser?

This discussion thread is closed.