AutoCAD Civil 3D General Discussion

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troma
Posts: 2,519
Registered: ‎05-21-2008
Message 31 of 36 (761 Views)

Re: Offset a surface

11-19-2012 09:29 AM in reply to: neilyj

Neil,

looking at your pretty picture there; isn't a MAPCLEAN going to delete one or the other of the endpoints on the magenta lines?  If so, that's not correct either.  Neither endpoint is right, the intersection of the lines is the point you need.

Sounds like we need some sort of TRIM & EXTEND command for surfaces, to find that intersection (or FILLET with zero radius).


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neilyj
Posts: 3,694
Registered: ‎08-01-2008
Message 32 of 36 (754 Views)

Re: Offset a surface

11-19-2012 10:25 AM in reply to: Sindarin
indeed and that pretty picture is only considering a 2D view, its even more complicated in 3D.

mapclean, snap clustered nodes is about the best approximation at the moment
neilyj
(No connection with Autodesk other than using the products in the real world)


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neilyj
Posts: 3,694
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Message 33 of 36 (748 Views)

Re: Offset a surface

11-19-2012 10:27 AM in reply to: Sindarin
and as Allen said its worse as the offset increases.
neilyj
(No connection with Autodesk other than using the products in the real world)


IDSP Premium 2015 (mainly Civil 3D 2015 UKIE & Infraworks with some limited 3ds Max Design)
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ArchD
Posts: 312
Registered: ‎07-30-2008
Message 34 of 36 (728 Views)

Re: Offset a surface

11-19-2012 01:23 PM in reply to: el.Topo

I just tried vk_topos method and it is pretty fast. But I do believe after creating the new offset surface a step or two should be added.

 

Setting it to show points only and extracting them so that MAPCLEAN can be used to consolidate the point clusters down to one point per cluster, and added those consolidated points to a new surface will give it a more accurate offset surface and smaller file.

 

I think until Autodesk adds this to Civil 3D, this will be my method of choice. 

Archie Dodge

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troma
Posts: 2,519
Registered: ‎05-21-2008
Message 35 of 36 (714 Views)

Re: Offset a surface

11-19-2012 02:04 PM in reply to: ArchD

Archie, as Allen said: "The problem is that the solution would be the intersection of the 3D Faces.... Not the average of the endpoints."

So I don't see how Mapclean gets you a more accurate surface.  Smaller file, yes.  And probably no less accurate, but not more accurate.


Credit where credit is due! Give kudos or accept as solution whenever you can.

New Member
JoseJoseJoseJose
Posts: 1
Registered: ‎12-11-2012
Message 36 of 36 (671 Views)

Re: Offset a surface

12-11-2012 08:29 AM in reply to: troma

Guys:

 

I read this topic with interest and I have something to share.

If you have access to ArcGIS and the extensions Spatial Analyst and 3D Analyst, you can basically build a TIN on ArcGIS, convert to raster, and use the raster calculator to get an approximate offset, then convert back to contours. I used this procedure many times to do offset surfaces and tapered offset surfaces. I can post detailed instructions if you guys are interested.

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