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A better way to trim a triangulation

A better way to trim a triangulation

Be able to trim triangles on the edge of the surface which have no inner angle greater then 90gr and the opposite edge not being part the surface boundary or a surface breakline.

I created a little tool using .net to do so, but more as a prove of concept. Hence, I like it to be a setting in the surface definition tab.

16 Comments
BartDeMaesschalck
Contributor
Must have feature

 

joantopo
Mentor

In the corridor properties, you can create a corridor surface and there is a tab to add boundaries for the corridor surfaces.

 

Don´t you like those boundaries?

 

I don´t like the behaviour of Civil 3D when we enable and disable some regions of the corridor which they are in the curve such as a roundabout because in that case there is "irreal" triangulation between regions. In the disabled region carry on with triangulation.

 

This is very annoying specially when we enable and disable regions.

 

 

opatis
Participant

Hi Joantopo,

 

This method will work for all surfaces. It is particularly useful for non-corridor surfaces as those are created using 3d polylines either from a survey or import from other design applications for instance. So they do not originate from a corridor.

 

I understand your problem. Are you looking for a way to discard those triangles? I might work if you add max-triangle link and use the region length as a property. But then again if other regions are longer, they too get discarded. You might want to post this as an idea too.

 

Jeroen

The Surface Build operation "Use maximum angle" and setting the "Maximum angle between adjacent TIN lines" to 90 is intended to clean up TIN surfaces exactly as you are showing in the video. Are we missing something in that operation?

 

Regards,

 

Peter Funk

Sr. Product Manager

Civil 3D

Autodesk, Inc.

joantopo
Mentor

I think that the "Maximum angle between adjacent TIN lines" just makes sense  if it is a corridor surface, where points are in the same station.

It is not appropiate to non-corridor surfaces, where in general, we must to add a outer boundary from a polyline. I don´t know another method to non-corridor surfaces.

 

 

Do you have an example of where it wouldn't work on a non-corridor surface? The surface settings was designed to work on non-corridor surfaces. For the corridor surface, in many cases the corridor can supply the boundary automatically from the point codes.

 

Regards,

 

Peter Funk

Sr. Product Manager

Civil 3D

Autodesk, Inc.

opatis
Participant

Hi all,

 

To better explain it; this function will not only remove a triangle with a check on maximum angle between adjacent TIN lines (eg 90gr). but check the opposite TIN line (= TIN edge) if that is part of a breakline. If it is not, the triangle will be deleted.

 

I created an update screencast that displays the different results of both methods. First the surface is created from 3d polylines by adding those as surfacebreaklines. Using the max angle function in the surface definition tab all triangle will be deleted even if the are valid (inside of the breaklines). This is not usefull. So an additional check should be done which is demonstrated in the .net application.

 

Theoretically the current max angle function works for most of the non-corridor surfaces but not on those that have for instance an daylight that changes from cut to fill or that have sharp corners.

 

The example data in the screencast can be downloaded via this link: http://we.tl/ZLLqORhpzH

 

@peterfunkautodesk - I put the tool itself in my box account created by Tim for last weeks Civil3D Gunslinger if you want to test. I had a talk with Dave about it too he has an email with the .dll to test.

 

regards,

 

Jeroen

 

ceethreedee.com
Collaborator

@opatis I think @peterfunkautodesk is asking if you have actually used this in the surface propsoerties-> build definition?

It works exaclty as you are are describing. Only trims outside triangles for the "maximum angle" setting. Maximum length will trim triangles anywhere.

 

See my blog post here for full use.

http://ceethreedee.com/drawing-management/drawing-production-cheats-for-civil-3d-objects-slope-shadi...

ceethreedee.com
Collaborator

Saying that. Its pretty annoying where this is stored @peterfunkautodesk. See my idea here to move this outside of the surface proerties box so that you can edit multiple surface defintions at once.

opatis
Participant

@ceethreedee.com please look at the screencast I posted in the comments on februari 2nd. 

It's shows the results of the two methods and no, also valid triangles on the inside are deleted unfortunately using your settings. Btw maximum triangle set to 5m is too less for most of our work so I prefer not using this option at all as you also mention that inside triangles are deleted then sometimes...

Looking at this again, the change that we need to make is for the max triangle angle build option to not remove any tin edge that is part of a breakline. This isn't a whole new way of working or a new command.

 

FYI, with the existing software, if you just set the max triangle edge to 120 and turn it on, you will get a tin that has only 3 extra triangles in it.

 

Cheers,

 

Peter Funk

Sr. Product Manager

Civil 3D

Autodesk, Inc.

Status changed to: Accepted
 
opatis
Participant
Yes, adding that check would be most welcome. But remember to check opposite edges of that specific angle.

And 3 triangles seems not much but the setting of eg 120 might be different with each surface and the invalid trangles too. The suggested change to the angle check will work for all.

Thanks a lot anyways for the followup

The change we're looking at making is that for both of the automatic edit operations: triangle length and max angle, we never remove a triangle edge that is from a breakline.

 

With this change in place, you could set the max angle to 90 the surface should match your surface triangle for triangle.

 

Cheers,

 

Peter Funk

Sr. Product Manager

Civil 3D

Autodesk, Inc.

opatis
Participant
Great! Much appreciated.
Rgds jeroen
gherrmanRQ549
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