“I need to get a surface from Civil 3D for InRoads, I’ll just export a LandXML file, right?”

by Seth Cohen, CADmanage.com

So, you are asked to give a surface that you created in Civil 3D to a company that uses Bentley InRoads.  You assume, because you have heard it from everyone, just export it to LandXML and all will be good.  Well, that works……….sometimes.  Let’s look at some reasons why this is not always %100 correct.

In the example below, my surface in Civil 3D looks perfect.

Surface in Civil 3D

Surface in Civil 3D

However, when the surface is translated in InRoads from the LandXML file, this is what it looks like.

Surface in InRoads

Surface in InRoads

So, as you can see, sometimes it is not a one-to-one translation.  In this example the reason the surface did not come in properly is that in Civil 3D, the triangles were deleted and a surface boundary was not used to “bound” the surface.  The solution in this example is to extract the boundary of the surface in Civil 3D, and bring it into the surface as an Outer Boundary. When the surface is translated into InRoads, the surface boundary will come in as a breakline, allowing the InRoads user to use the boundary to create an Exterior Boundary (as it’s called in InRoads).

Another issue is shown below in the following images:

TIN in Civil 3D

TIN in Civil 3D

TIN in InRoads

TIN in InRoads

As you can see, the triangles don’t match up, and the InRoads user is not going to know that the triangles are incorrect.  Now sometimes this is more of an issue in each software package and the different algorithms used to triangulate the surface, and the InRoads user will have to Change Triangle Edges (Swap Edge in Civil 3D) to match the correct triangulation.  However, with the correct data provided to the InRoads user, the surface can match the Civil 3D version.

So, what can you do to ensure that an accurate surface will be reproduced in InRoads?  Here are some tips that will help ensure a more accurate model representation.

    • Add an exterior boundary to the surface (as mentioned in the first section)
    • Make sure the surface is using a style that shows triangles, and export the DWG to either a MicroStation DGN file or AutoCAD graphics.  This will allow the InRoads user to see how the surface should look (triangulation-wise).  Additionally, the InRoads user will have whatever 3D graphics they will need to make the surface work correctly.
    • Verify that the necessary settings are defined in the LandXML Settings dialog box.  This dialog box is found in the Settings tab > right-click on the drawing name > Select Edit LandXML Settings.

“Now you know, and knowing is half the battle.”…………G.I. Joe

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: