Offset TIN surface

[caruga1]

Hi, everybody! I would like to know is there any possibility to create offset surface from existing TIN surface (not rise / lower) ? Thanks!

[wfberry]

What does offset mean, laterally?

Export surface via LandXML.  Rename current surface.  Import LandXML.

I am sure you can just move it laterally, I have had no reason to try it.

Bill

[caruga1]

Hi, wfberry! Maybe I wasn't clear enough - i have to offset existing surface normal to itself, not move it laterally - but can't realize the way to do it in C3D... I can extract triangles from existing surface and than offset them using surfoffset command and create TIN again, but this method is not very accurate and it is time consuming. I'm looking more automatic and more ACCURATE way to do it... Let say that offset surface represent excavation line and has to be very accurate in this case.

[SkipBurns]

I'm a little confused by your explanation, but I think that what you are trying to do is create a copy of the existing surface that is lowered by a certain amount.

If so, create a new surface and use edit-"paste surface" to paste the existing surface into that one.  Then use edit-"raise/lower surface" to lower that surface by the amount.

You will then have two surfaces.. the existing.. and the "excavation" surface.

[caruga1]

I would like to create surface to be offset normal to the triangle faces of existing surface. I posted picture below that illustrate difference between offset and rising / lowering. In the First picture is shown what I'm trying to achieve. Thanks!

[caruga1]

Here is the picture

[Neilw_05 · Accepted solution]

This question has been raised several times in the forums. Try a search for offset+ surface+normal.

AFAIK there is no way to do it.

[caruga1]

Thanks!

[Joe-Bouza]

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@caruga1 wrote:
Hi, wfberry! Maybe I wasn't clear enough - i have to offset existing surface normal to itself, not move it laterally - but can't realize the way to do it in C3D... I can extract triangles from existing surface and than offset them using surfoffset command and create TIN again, but this method is not very accurate and it is time consuming. I'm looking more automatic and more ACCURATE way to do it... Let say that offset surface represent excavation line and has to be very accurate in this case.

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No kidding. What happens when two normal vectors intersect at the offset distance? Or diverge and the surface area gets larger? sounds undefined and redefined to me.

What are you building that a datum excavation wouldn't give a close enough representation of the volume?

[caruga1]

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@Joe-Bouza wrote:

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No kidding. What happens when two normal vectors intersect at the offset distance?

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Please, see picture I have posted in my earlier post.

I said that offset line represent excavation line not that i'am looking for excavation volume. What i'am looking for are new positions of grade brake points

on the offseted surface.

[abekip]

Did you ever find a solution to this? It is suprising Civil 3D does not have this capability as it is very relevant in projects ranging from land dev to environmental. I have worked in both fields and have always needed the use of an offset feature to find subgrades and also do define clay liners in construction drawings. Everybody seems to just suggest copy and pasting the surface up or down, but that obviously would not suffice.

[AllenJessup]

I've been involved in discussions about this for over a decade. Still no solution. I took a lead from your post and added this to the Idea Station.

For a bit on a previous discussion. See HERE.

Allen

[eirij]

Hello Everyone,

Have you guys found any solution to this? 

[AllenJessup]

Not me.