Creating Surface From USGS NED Files

[jakeamericus]

I have been reading and researching the issue on how to create surface information from a USGS NED file. I have found some round-about ways that involve importing a .adf file from map3D and creating polyline object information. What I did was, created and new surface-> expanded that surface in the prospector window -> expanded the "Definition" tab -> right clicked "DEM Files" and selected add-> navigated to to my folder with the NED file in it and select the largest .adf file and imported that. It created a surface with contours just like if I had imported a USGS DEM file. However, I didn't check the coordinates, I assume they are off and would have to be properly adjusted. This seems a whole lot easier then some of the other explanations, unless I am missing something or if this method produces a totally incorrect surface. Anyone have insite on NED surfaces in Civil3D? Edited by: jakeamericus on Apr 15, 2010 5:29 PM

[Anonymous]

It sounds like you are using the proper workflow in that you are creating an
empty surface and then adding the DEM vs. creating the surface directly from
the DEM. Therefore, when you add the .adf file to your surface object you
should see an option to specify a coordinate system in the dialog. If your
DEM CS does not match the drawing CS, you will need to specify the DEM CS in
the dialogue. C3D should then reproject it to fit the drawing.

[jakeamericus]

Thanks I'll give it a shot.

[jakeamericus]

do you know what the coordinate input information is for NED files? I know these files are created with the NAD83 but when I select this option in the "Select Coordinate Zone" while creating a new surface in Civil3D I don't know what the "Available coordinate systems:" should be set at...also do you know if there are any issues with XFEFing surfaces created from a .adf file?

[Anonymous]

See my reply to your subsequent post regarding the CS. I don't know what
issues you have in mind with XREF's. The surface should behave as any other
C3D surface.

[jakeamericus]

got it to work, I was using UTM NAD 83 but needed to use Lat/long 83 (LL83)...now, the surface is in to coordinates but was produced using meters, do you have any ideas how to convert elevations from meters to feet during the import of a .adf file?

[HC1975]

1. Set the coordinate system in the drawing:
i usually start with a blank drawing, save it and then go to TOOLSPACE, Edit Drawing Settings Tab, right click and choose the correct CS under "Units and Zone".

2. Import the USGS file and it should covert it to the currents CS and units (feet) as set in the "Settings TAB" in the background without any additional steps.

A webcast series details the steps:

http://www.adskmedia.com/civilwebcasts/archive.php

"Competitive Road Design Series: Integrating Geospatial Data with AutoCAD Civil 3D"

[nlthompson]

yeah, I had the same problem...how do you get meters to convert to feet as part of bringing in the .adf file?