How to add Datum NAVD 88?
naominch
Global Mapper User
I am very new to use global mapper. I want to add NAVD 88 datum. Is there available date to load for it?
Thanks.
Thanks.
Comments
-
Howdy,
As I understand it (which may, or may not be entirely correct) Global Mapper doesn't do vertical datums. The "datum" option on the projection dialog is for horizontal datums only. GM loads each separate elevation data layer with that file's "zero" as mean sea level, or 0 ft/m above sea level. That's it. You can make the adjustment from whatever the elevation file source says is it's datum to NAVD 88 by using the "alter elevation" tab for the layer.
Theoretically, you could use the "combine terrain" function, and combine an elevation layer with a digital "geoid", or a digital map of the NAVD 29 - NAVD 88 adjustment, or both; but I haven't done this yet. There would likely be some resolution/resampling issues with that.
Regards,
Mark -
Hello,
In order to use vertical transformations in Global Mapper, you would have to also have our Geographic Calculator product. Global Mapper can integrate with Geographic Calculator to allow you to work with geoids (including NAVD88) for vertical data.
For more information: Geographic Calculator
Cheers,
Bob -
Hi Bob and Mark,
Thank you for your comments. It's very helpful understand about meaning of zero. We might need to think about buying geographic calculator.
Thanks!
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