Visualization of LiDAR by sub-meter elevation
George Chandeep Corea
Global Mapper UserTrusted User
I am trying to use GM14.2 to visualize and manually identify road defects using terrestrial lidar. Unfortunately I can not find a shader to uniquely colorize sub meter variations in elevation. This process works perfectly in the free Mars Viewer.
I tried to create a custom shader which would work but is very labour intensive as I have to manually enter a color for each 0.1m change in elevation...at least to the best of my knowledge.
The LAS files are loaded into a GMC and I have tried to view it by first return only but that doesn't help. I also tried some of the options discussed in http://cws.unavco.org:8080/cws/learn/uscs/2008/2008Lidar/handouts/Global_Mapper_and_GLW.pdf
Please see Options for manually identifying road defects from Terrestrial Lidar - Geographic Information Systems Stack Exchange for an example comparing GM with Mars and other software.
I tried to create a custom shader which would work but is very labour intensive as I have to manually enter a color for each 0.1m change in elevation...at least to the best of my knowledge.
The LAS files are loaded into a GMC and I have tried to view it by first return only but that doesn't help. I also tried some of the options discussed in http://cws.unavco.org:8080/cws/learn/uscs/2008/2008Lidar/handouts/Global_Mapper_and_GLW.pdf
Please see Options for manually identifying road defects from Terrestrial Lidar - Geographic Information Systems Stack Exchange for an example comparing GM with Mars and other software.
Comments
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You can specify the min and max range to use, then use the 'Evenly Space Elevations' button on the custom shader dialog to create elevations every 0.1 meter apart. Then just edit the colors as needed.
Thanks,
Mike
Global Mapper Guru
geohelp@bluemarblegeo.com
Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation -
Thanks Mike. I have tried this but the problem is that I then need to do this everytime I move the screen. Is there any way to get the color palette to only consider the data on screen and then assign unique colors (not a shade) to each elevation category.
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Oh I see, that is actually something on our todo list, but there isn't a way to do it just yet. Hopefully in v15 though!
Thanks,
Mike
Global Mapper Guru
geohelp@bluemarblegeo.com
Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation -
Thanks Mike -that would be great. Currently only Mars7 does this properly and I just spoke with ERDAS who are also looking at adding the feature in. Basically the ability to automatically generate the elevation grid based only on the points in the current view.
For now can I use GM to quickly extract just the ground and last return points that are within a polygon buffer of the road center line? I assume that if the software is restricted to just this data without major elevation changes, it will then symbolize more appropriately...is this correct?
If so can I script the clip road center to extent of lidar--buffer--extract--load--identify small changes on surface process as a GM script in 14.2?global_mapper wrote: »Oh I see, that is actually something on our todo list, but there isn't a way to do it just yet. Hopefully in v15 though!
Thanks,
Mike
Global Mapper Guru
geohelp@bluemarblegeo.com
Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation -
Yes you could extract a new file cropped to some buffer, then load that back either by itself, or with a non-shared shader assigned to it on the Options dialog for the layer so that only the elevation range of that layer is considered.
Thanks,
Mike
Global Mapper Guru
geohelp@bluemarblegeo.com
Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation -
global_mapper wrote: »Oh I see, that is actually something on our todo list, but there isn't a way to do it just yet. Hopefully in v15 though!
Thanks,
Mike
Global Mapper Guru
geohelp@bluemarblegeo.com
Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
Has this been implemented in 14.2? I notice that there is a lidar shader but that doesn't seem to resolve the issue.
best, -
It's not in v14.2. It's not done for v15 yet either, but might still get done for the final v15 release.
Thanks,
Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
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