Why are driveways so difficult?

[Jeff Kogut]

Since there is no driveway tool (and there really should be) does anyone have a trick to trim a mesh around a complicated polyline shape?

I have made a copy of my site mesh, changed it to an asphalt material, elevated it 3", and would like to trim it to my 2D polyline driveway shape. To my mind this should be a 2 minute operation to create this driveway. But I see no way to trim to the polyline so as to keep the elevation data. I don't want to spend an hour moving points around.

Don't say morph it! Morphing something like this means moving many points and it's prone to all sort of pitfalls.

As the images show I can trim the outward edges and maintain the elevation data, but inside corners are impossible. Why can I not just be in the mesh tool, highlight the mesh, and spacebar click the polyline to trim? (The blue line is a polyline.)

[Jeff Kogut]

[Jeff Kogut]

[alemanda]

You could use SEO Intersection between a slab (the driveway) and the elevated (copied) mesh with asphalt material.

[Eduardo Rolon]

They are not 😉
This is a very old trick, possibly since AC8.1

Requirements:
• Mesh A = the ones with the contours
• Mesh B = The one that defines the path and has no contours and it intersects M-A in the Z coordinate. Previously we used a Slab for this but with BMats it creates major slow downs since the Slab needs to be calculated for the whole site.

Optional if you need the path either lower or higher than M-A then you will need copies of the previous meshes and lets call them:
• Mesh A2
• Mesh B2

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1. Using SEOs subtract M-B from M-A. M-B should be in a dedicated SEO Layer so that you can turn it off or wireframe if editing. The result is a hole tracing the path.

2. Using SEOs intersect M-A2 with M-B2 so that you get the path following the contours

3. Move M-A2 up or down (Z) to either have the path lower or higher than the base Terrain M-AB

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Usually I make the copies side by side and group them by set and them move one on top of the other. Editing the path later is easy since you can edit both of them at the same time because they share the same nodes.
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If by some other reason you don't need a difference in height between driveway and terrain then you can try
1. Subtract with Upwards M-B from M-A and select Keep Original Surface
2. Then do an Intersect with M-A and M-B
The result should work though I don't normally do it this way

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This procedure should not slow down the model but if you have a "Huge" site plan it might be easier to divide it into easier chunks to work with.
Hope that I have not forgotten any steps.

[Jeff Kogut]

Thanks ejrolon! After I figured out the explanation it worked.