I have a drawing from Civil3D, a .dwg, and I have a land xml that was created from that data set by original drawing creators. Also, there was a .dgn created from the same .dwg file, which has some visible contours shown in .dgn. When I view .dgn and then create a terrain model with xml, to verify contours are correct, the terrain model contours and contours displayed in the .dgn, are consistently off horizontally. Seems to be an international foot to US Survey foot difference, since horizontal is off by about 3 ft everywhere. Cannot seem to be able to get the contours to overlap original drawing. Please, help!
See picture: Yellow are the terrain model and white are the dgn contours.
Hi,
I might check out your coordinate systems? makle sure to lok at EDITDRAWINGSETTINGS in C3d and check if there is scakle factor applied an also check the Coordinate system your importing into also they should match or you can correct up the coord system in openroads im not 100% sure if its the correct coordinate or reproject but try both see iof that helps
When attaching a DWG, you have a chance to select DWG units. You need to specify US Feet vs just Feet, which is actually International Feet. One work-around is to turn off True Scale in the reference attachment and then set the scale factor to 1:1.
Charles (Chuck) Rheault CADD Manager
MDOT State Highway Administration
Yes as Joshua and caddcop indicate, best to know the data within the DWG if at all possible. (What state plane, datum, etc.) Using the Geographic tool (simply hit F4 search for "coordinate system" tool). will give you the option to assign a state plane to the file prior to attaching the DWG. Notice the list of state plane options have Foot/Meters, etc, so choose wisely. Once those are the same, your problem should be solved. If you don't know how the DWG was created (usually a data set from USGS or similar online source), most cases you'll be able to narrow down the choices based on the project state plane location.
Bentley Accredited Road Designer | Bentley Accredited Road Modeler
colliersengineering.com
Thanks, Josh. Just as my Gut was telling me, it was a foot to US survey foot discrepancy. ORD was thinking that the C3D file was foot and not USSF, therefore was correcting for that, but was incorrect. I think I am good to go now, everything is lining up. Now, time to re-do everything and write it down and take screenshots, so I can replicate next time!
I appreciate the response, Chuck. Like I told Josh, above, it is the fact that in C3D, there are two units of measure location (like ORD). One is the GCS, which will state Washington South us survey feet (nad83), and then under drawing utilities > units > drawing units > insertion scale. The unit of measure listed there, needs to be USSF, otherwise if its set to feet, ORD pulls that unit and thinks the data is is international feet (from what I am gathering and understanding). So, what I did was, open the dwg in civil3d, then change that unit of measure to USSF, save as a different copy, then brought that copy into ORD. This time, ORD asked me to select what unit of measure the data is in, instead of telling me that it was in feet and not giving me any other options. Thanks!