Generating a Elevation Grid result on different X and Y spacing...
Dionybell
Global Mapper UserTrusted User
I have a Lidar data (las file) with points that I got from an UAV flight. The grid of points has a regular spacing of 0.15 m.
I use the Autoclassify Ground feature (on another software) to classify to Ground Points. It's the same method GM uses.
But when I try to regenerate a Elevation Grid using just these points (Ground Points) I get an X spacing of 0.28 and a Y spacing of 0.095 m.
Is this normal? Did I make a mistake. I thought it was optimal if the grid spacing is very similar.
Is there any risk to use that Elevation Grid? I notice that the new Grid looks worse than the old one in terms of resolution.
Thanks in advance. Please help.
I use the Autoclassify Ground feature (on another software) to classify to Ground Points. It's the same method GM uses.
But when I try to regenerate a Elevation Grid using just these points (Ground Points) I get an X spacing of 0.28 and a Y spacing of 0.095 m.
Is this normal? Did I make a mistake. I thought it was optimal if the grid spacing is very similar.
Is there any risk to use that Elevation Grid? I notice that the new Grid looks worse than the old one in terms of resolution.
Thanks in advance. Please help.
Comments
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When you generated the elevation grid what type of gridding did you use (i.e triangulated TIN, min/max/avg binned grid, etc.)? The TIN grid will clamp the maximum grid dimensions to 10000 samples in either direction if you choose the automatic spacing option, which could result in the spacings that you see. You can manually specify the spacing to use, or if you have the Lidar module use the bin grid methods with a native point spacing multiple or spacing in meters. The Lidar module binned methods will generate the grid much faster than the TIN method.
Thanks,
Mike
Global Mapper Guru
geohelp@bluemarblegeo.com
Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
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