The 45 minutes was just to convert the points. But exporting the point file, conversion and creating a Surface from the converted point file doesn't take to long. Maybe 10 minutes of less.
You might be able to get a point file quicker using Data Extraction. I was going to take lunch anyway so I thought I'd let it run and see if it would create the points. BTW. Make sure that point creation is set to Automatic for Elevation and None for description.
It is possible to non-uniformly transform a Civil 3D surface. Assuming the end result you are looking for is just a surface (or DEM/XML file extracted from a surface) then you can:
- turn the surface into a block (be sure to turn on non-uniform scaling and exploding)
- scale the block Z by 3.28084 (or as needed)
- explode the block
- if you look at the surface definition, a transformation has taken place (although the values given for the transformation are not useful to identify what has actually happened) and the elevations are now scaled
- note that this is a copy of the surface; the original surface is in the block definition; purge the block to get rid of the original
I'm not sure this is exactly what you are looking for but it does create a usable surface. If you are attempting to scale surfaces with a vary large number of points your results may vary.
This same non-uniform scaling can also be done with a bit of programming to bypass having to use a block. Extremely large surfaces can be adjusted in a few seconds with this method.
When it comes to DEM's, the size of the dataset makes any multistep process prohibitive. We really need a way to either pre-process the data before building the TIN or simultaneously transform it during processing.
- scale the block Z by 3.28084 (or as needed).
That might work going from meters to feet within the same system and could have worked after I brought the data in to our current system. But it won't work going from one system to another. I'd have to test it against one that was already transformed to see. Transformation from one system to another involves more than a scale factor.
I'm happier exporting the points from UTM and using Corpscon to do the transformation. The files the Army Corps of Engineers developed for Corpscon are the same ones that Autodesk uses for transformations in Map and Civil in the U.S anyway.
Thanks for the suggestion.
All I was trying to state is that if you have already transformed the XY then all you need to do is correct the Z. The non-uniform block scales the Z and leaves the XY at 1.
Yes. That would work in that case. I didn't mean to sound dismissive. I'm just finicky about using the proper transformation. We're going to be melding this with Survey later so I don't want to have to adjust much.
When I first saw your post I assumed you were suggesting exploding the surface, making the graphics into a block, rescaling the Z factor, exploding again and recreating the surface from the graphics. That process would take far too long.
Looking again more closely I see now you are just making the surface into a block, rescaling the Z factor then exploding it. That sounds like a doable workaround. I'll run some tests when I get some time.
Use Global Mapper to convert the file to the required datum, projection, and units.
Set coordinate System in GM
Load Source file
Export elevation grid format. USGS DEM
Set output units on options tab
Creates a 1meg point file in 45 seconds.
As far as I know, Global Mapper does not support NED. Can you confirm that it does?
I've spent quite a bit of time looking for a utility that can transform NED files. If anyone knows of one, please pass it on.
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