Global Mapper Pro

Export elevation data to ASCII Arc Grid with geographic xllcorner and yllcorner

Lance
Lance Global Mapper User
edited November 2012 in Elevation Data
Sorry for being a noob, but how do I export to ASCII Arc Grid so the resultant file has xllcorner and yllcorner values in decimal degrees (i.e. geographic)?

No matter what options I've tried, I get the following:


xllcorner -401151.13574
yllcorner 146703.19750
cellsize 0.333333



I'm using GM 12.02.

Thanks for any help!

Comments

  • global_mapper
    global_mapper Administrator
    edited November 2012
    You need to go to the Projection tab of the Configuration dialog and set the view/export projection to Geographic (lat/lon). Then your export will be reprojected to lat/lon and the corner coordinates stored as such.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • Lance
    Lance Global Mapper User
    edited November 2012
    You need to go to the Projection tab of the Configuration dialog and set the view/export projection to Geographic (lat/lon). Then your export will be reprojected to lat/lon and the corner coordinates stored as such.

    Sorry, that doesn't work - as that is what I have been doing.

    Essentially, I import the large area DEM data with a geographic projection, WGS84 as the datum, arc seconds as the planar units and meters as the vertical units. The input data looks correct when displayed and queried.

    I try to export a portion of the data to ASCII Arc Grid format - but before doing so, I choose Configure and verify the projection is geographic and the other parameters are the same as previously set. It exports, but I always get cartesian coordinates for the xllcorner and the yllcorner. I don't even know for certain what that cartesian system is.

    Any other ideas? Or please tell me what I'm doing wrong. Thanks!
  • global_mapper
    global_mapper Administrator
    edited November 2012
    Ah I see the problem, you mentioned you had your units set as 'arc seconds' for Geographic, so that is what you are getting for the corner coordinates. The older USGS DEMs use arc seconds natively. Change your units to Arc Degrees when you export and then you should get what you need.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • Lance
    Lance Global Mapper User
    edited November 2012
    Perfect! Works great! I can stop banging my head against the wall now. Thanks!
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