Averaged Elevation
kbellis
Global Mapper UserTrusted User
Hello,
Having previously taken a comparison (signed difference) between a layer of LAS LiDAR points in NAVD88 and the same points transformed (using VDatum) to MLLW, visually the average value of that difference appears to be about 1.795m ±0.002m. It doesn't seem possible to obtain a more precise value from Global Mapper, or am I missing something?
AVERAGES1.PNG
Thank you very much.
Kelly
PS. Mike - FYI & FWIW - this message was also mailed to you at 9:44 Eastern and is being posted on the forum at 9:47 Eastern (a little test for measuring the latency in your email server
Having previously taken a comparison (signed difference) between a layer of LAS LiDAR points in NAVD88 and the same points transformed (using VDatum) to MLLW, visually the average value of that difference appears to be about 1.795m ±0.002m. It doesn't seem possible to obtain a more precise value from Global Mapper, or am I missing something?
AVERAGES1.PNG
Thank you very much.
Kelly
PS. Mike - FYI & FWIW - this message was also mailed to you at 9:44 Eastern and is being posted on the forum at 9:47 Eastern (a little test for measuring the latency in your email server
Comments
-
Visually the value of the differences between the two layers is 1.795m ±0.002m
visual1795.png -
Once you have the difference layer calculated, create a coverage area for it, then select that with the Digitizer Tool and right-click and select the Measure submenu to calculate elevation statistics for the area. That should include the average elevation.
Note that your emails have not showed up yet, so I guess the forum is the place to use for most requests so I see your emails sooner.
Thanks,
Mike
Global Mapper Guru
geohelp@bluemarblegeo.com
Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation -
Thanks Mike. I'll give it a try.
Mail server issue weird, ain't it? -
Well - if it should have shown that average elevation, I may have done something wrong:
no average seen.PNG
This took a very long time but I only saw area and perimeter reported - no average elevation.
What might I try next? -
I tried this without much success:
no average seen2.PNG -
Oh wow no you just want one coverage area for the whole thing. Just draw a box around it and calculate the stats for that. Looks like you have millions of little features.
Thanks,
Mike
Global Mapper Guru
geohelp@bluemarblegeo.com
Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation -
ha ha on me
-
Mike - that worked just fine.. THANK YOU
average seen1.PNG
Categories
- 12.7K All Categories
- 5.6K Features Discussion
- 342 Downloading Imagery
- 1.3K Elevation Data
- 380 Georeferencing Imagery Discussion
- 628 GM Script Language
- 53 User Scripts
- 113 GPS Features
- 414 Projection Questions
- 819 Raster Data
- 1.3K Vector Data
- 6.6K Support
- 177 Announcement and News
- 908 Bug Report
- 558 SDK
- 1.2K Suggestion Box
- 3.7K Technical Support
- 562 Other Discussion
- 129 GIS Data Sources
- 27 Global Mapper Showcase
- 233 How I use Global Mapper
- 107 Global Mapper Forum Website