surface boundary repeatedly fails

[wkiernan]

I created a surface

and then I added a boundary (the white lline) and it gives me this

I've tried a 2d polyline, a 3d polyline, data clip vs. outer boundary, offsetting the boundary 0.1 feet outside the site, etc., etc. but I repeatedly get that v-shaped piece cut out of the surface.  This is where the last four hours of my day have gone; I could have gotten the volumes quicker with an HP-41.  Anybody have any ideas?

[Jay_B]

Nice drawing title 🙂

Can you post your DWG here for someone to take a look?

[seattlesurvey]

I run into similar situations of 'boundary fails' which I can't resolve.  My boundaries are snapped to points, so I verify the points are in the surface point group.  When I've eliminated that and other potential issues, I've ended up creating a breakline along the boundary in the area where it's 'failing,' and that always fixes things.  On a project where I may see several such areas, I create a feature line of my boundary, have it use the elevations from the surface, and then add it as a breakline and, voila, problems resolved.

So, not an explantion, but a potential work-around.

HTH.

[Anonymous]

Can you repost a screenshot with the TIN triangles turned on?
Are you using a non-destructive boundary?

[wkiernan]

What was happening was simple and easy to work around but somewhat unexpected.  Two TIN triangles crossed the boundary line so they got deleted; when I edited the TIN by flipping a TIN line the surface filled the white polyline.  But having read the docs I thought that, depending on whether the "non-destructive" box was checked, where TIN lines crossed a boundary they would be truncated at the boundary and an interpolated elevation assigned to the endpoints, and then the surface generator would make a new surface using those interpolated points.  I tried it both ways (checked or unchecked) but no go. 

I did this after reading your suggestion for a breakline, which I also incorrectly thought worked that way - that is, I thought where a TIN line crossed a breakline it would interpolate a new point, so thanks! yay! I get to go home tonight.  Here's to you:

So that's a solution, manually edit the TIN so none of the TIN lines cross the boundary, and I hope this will be of service to some other person searching the forum for "surface boundary."

[doni49]

What version are you using?  Duh.  Never mind -- it's in the screenshot:  2014.

[doni49]

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@wkiernan wrote:

What was happening was simple and easy to work around but somewhat unexpected.  Two TIN triangles crossed the boundary line so they got deleted; when I edited the TIN by flipping a TIN line the surface filled the white polyline.  But having read the docs I thought that, depending on whether the "non-destructive" box was checked, where TIN lines crossed a boundary they would be truncated at the boundary and an interpolated elevation assigned to the endpoints, and then the surface generator would make a new surface using those interpolated points.  I tried it both ways (checked or unchecked) but no go. 

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All points outside of the boundary will be completely excluded from the surface definition. 

Now on the other hand, let's assume for a second that you draw your boundary line such that it's NOT on any surface points and/or breaklines.  Then you add it as a boundary with the non-destructive option turned off.  You're basically adding a breakline that will also serve as the boundary.  If you draw your boundary by connecting surface points, then you won't see any change other than eliminating triangles that are outside the boundary.