Show meters instead of feet in contour lines
Greina
Global Mapper UserTrusted User
I imported some contour lines from an *.mp file. GM writes the elevation data in feet (I presume) instead of meters. In Configuration > General Tab I already have meters as default for distances.
Comments
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By default the MP export uses feet, but you can change that by providing a template file that specifies the elevations to be in meters. In reality it doesn't matter since the actual GPS unit will convert the saved elevation values to whatever the user has setup for their unit preferences and display them that way. So long as you aren't physically looking at the text file in a text editor it doesn't matter how the units are stored.
Thanks,
Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
http://www.globalmapper.com -
Thanks. How must the template file look like and where to store it?
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The template file is just any valid MP file, although only the header is used. Just save one that you created and edit it in a text editor and change the Elevation field in the header to have a value of M. You can delete everything but the header. You select the template file on the MP export dialog, so the actual location doesn't matter.
Thanks,
Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
http://www.globalmapper.com -
Mike, I exported my contour lines from the *.mp file into *.gmg format (gridded export). I stated two small problems:
I have to confirm with "yes to all" to every single tile to accept constraint lines (no idea what this is). So an overnight export is impossible.
The export file looks a little bit strange at its border, in other words it shows no clear border. Please have a look to the screenshot.
ScreenShot248.jpg -
How are you doing the export from MP to GMG? Are you using a script or something like that?
The strips you are seeing are where the convex hull is filled. If you use the grid tightness slider (or script value) to make that close to tight then you won't get those.
Thanks,
Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
http://www.globalmapper.com -
Ah, now I know what error you are talking about. Occasionally when a data set has stacked points and things like that there will be an error adding a line segment (like from a contour) as a constraint so the points have to be added individually. This warning would appear once per operation if it happens. I have updated the gridding operation so if you are doing multiple grid cells the warning shouldn't be shown so you can do large overnight operations without interruption. I have placed a new build at http://www.globalmapper.com/global_mapper13.zip with the change for you to try. Simply download that file and extract the contents into your existing v13.xx installation folder to give it a try. If you are using the 64-bit v13 version there is a new build at http://www.globalmapper.com/global_mapper13_64bit.zip .
Let me know if I can be of further assistance.
Thanks,
Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
http://www.globalmapper.com -
Yes, gridded export works fine now without any error questions. Thanks!
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global_mapper wrote: »How are you doing the export from MP to GMG? Are you using a script or something like that?
The strips you are seeing are where the convex hull is filled. If you use the grid tightness slider (or script value) to make that close to tight then you won't get those.
Mike, I tried this solution: I manually created an area feature all around the contour lines and did the export with the "crop to area feature" option. This worked best.
Is there a chance to let GlobalMapper do the job to create this area feature instead of my manual work? -
That would be nice, but unfortunately what is obvious to human eyes in terms of where that area should exist is not so obvious in an automated way. By default it is already cropped to the convex hull of the input 3D points, but this of course crosses chunks of missing data on the triangles between your square regions of actual data. Obvious what you actually want by looking at it, but there are lots of cases where you have irregular data with inlets and other regions that have no nearby data but should be filled. The only way to automated filling inside a convex hull is to use the "no data" distance threshold to just say you want data near actual data points. This would automatically discard stuff in the big no data regions, but if you are gridding from contours could also leave holes if you have widely spaced contours.
Let me know if I can be of further assistance.
Thanks,
Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
http://www.globalmapper.com
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