export elevation grid changes elevations from source grid?

TreebeardTreebeard Global Mapper UserPosts: 25Trusted User
edited April 2015 in Technical Support
I have really been struggling on exporting grid information and having it change my data elevations. For instance, I may bring in points, lidar, grids etc. and when I export them as a new format grid, then load them back in it always changes my elevations identified on my vertical legend. Ie. I can export a smaller area from a larger data set and when I import the generated data set the legend scale identifies elevations that are way outside the original data elevation range.

I have to be missing a toggle or something? if I have data in UTM meters and I want NAD 83 state plane feet, then I set the state plane coordinate system in the config dialogue before I import. This always seem to reproject the UTM data to my desired state plane system when I import. Is there something in this process that is affecting my data export and resulting change in elevations. There must be a toggle I missing somewhere in the export dialogue?

Please help!

Comments

  • dcoggindcoggin Global Mapper User Posts: 259Trusted User
    edited April 2015
    Check the Vertical Options tab in the Configuration dialog. The selection in the box Elevation Display/Export Units affects the exported elevation units. Exported elevations also depends on Global Mapper correctly interpreting your original elevations. For file formats that do not natively include elevation information (e.g. shapefiles, ArcASCII grids) make sure the correct selection is made when importing or once imported check the Feature Types/Labels/Elevations tab of the Vector Options dialog (Overlay Control Center - highlight layer - Options button). The units there seems to tell you how GM is interpreting elevations in that layer. A combination of that setting and the export setting in configurations will affect the exported elevation value. I have to be very careful with this also.

    Hope that helps,
    David
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