Re-create a Civil 3D Model from AutoCAD Data
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Hello, in this video I am going to show you how to recreate a Civil 3D model from an existing CAD drawing. For example, I have a drawing here that shows an alignment, some contours, and a profile view. However, if you click on these, you'll see they are just CAD lines, not Civil 3D objects. So, I'll demonstrate how to create a Civil 3D model from this data to enable modifications. Since a CAD drawing doesn't allow Civil 3D modifications to profiles or other elements, I'll show you how to create a Civil 3D model from this CAD data.
Our first step is to create a surface using the contours in the drawing. If you select one of these contours and check its properties, you'll notice it has an elevation. These contours are polylines representing elevations. I'll select all these contours, choose "Select Similar" to ensure only contours are selected, then copy them and paste them into a new Civil 3D drawing. This new drawing uses a template where we remodel elements from the AutoCAD file. After pasting, I'll create the surface by right-clicking in the Prospector under "Surfaces" and selecting "Create Surface," naming it "EG" for existing ground contours. I'll set the label style to "Border Only" and then add the contours to the surface by expanding the "EG" surface definition, selecting "Contours," and adding them with the default parameters.
Next, I'll freeze the contour layer, as I no longer need to see the contours but still want them in the drawing. I'll create a new layer for the contours if necessary, to avoid affecting future drawings. With the surface created, I return to the AutoCAD file to continue modeling. I'll select and copy the alignment lines and curves, then paste them into the Civil 3D drawing. I'll create an alignment from these polylines, specifying the direction and erasing the original entities after creating the alignment. I'll then turn on the alignment labels, ensuring the alignment is accurate by checking the end coordinates.
After the alignment is set, I'll create the profile view by generating a surface profile from the EG surface and adding it to the drawing. I'll select a location for the profile view, noting that the profile will differ slightly from the original CAD file due to surface creation limitations, but it will be an accurate approximation.
To create the profile, I'll measure the vertical scale in the CAD file and ensure the datum is correct. Then, I'll copy the profile lines and tangent extensions from the CAD file into the Civil 3D drawing, using the 25 elevation as a base point. I'll convert this into a Civil 3D profile using the profile creation tools, snapping to endpoints and ensuring the profile aligns with the original drawing.
Finally, I'll add vertical curves using the "Free Vertical Curve Parabola" tool, setting the curve length by specifying points the curve should pass through. I'll ensure the profile closely matches the original CAD drawing by checking gradients, curve lengths, and other parameters. I'll also verify the elevations in the profile view properties, ensuring the finished ground profile is consistent with the original CAD file.
This process creates a Civil 3D model from AutoCAD data, allowing for modifications, material calculations, and other analyses, especially useful for consultants verifying contractor or client data.