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Message 1 of 11 (311 Views)

# Surface boundary problem

311 Views, 10 Replies
01-09-2014 06:06 PM

I have this surface that I have created

I drew a polyline around the site then added a boundary with a destructive break line because there were points outside the line I want to ignore but this is what I got.

You notice there are parts missing from the surface anyone know why it does this? Below is a zoom in on the bottom section that is missing.

I realise that I can do it with non-destructive boundary see below but why is it doing this, anyone know?

Any help is appreciated.

*Expert Elite*
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Registered: ‎11-08-2005
Message 2 of 11 (287 Views)

# Re: Surface boundary problem

01-09-2014 09:51 PM in reply to: allywhite666

A destructive boundary "destroys" any TIN triangle that crosses it - removing the entire thing.

In this case you may want to use a non-destructive boundary, which works more like the ACad TRIM command - clipping the existing TIN triangles at the boundary and then connecting the end points with new lines to form new triangles.

Steve
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Valued Contributor
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Message 3 of 11 (283 Views)

# Re: Surface boundary problem

01-09-2014 10:00 PM in reply to: sboon

But non-destructive will include all the points outside the boundary. There are two triangles it should have created in the example below.

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Message 4 of 11 (277 Views)

# Re: Surface boundary problem

01-09-2014 10:13 PM in reply to: allywhite666

But non-destructive will include all the points outside the boundary.

Nope - The new surface edge will stop at the non-destructive boundary.

There are two triangles it should have created in the example below.

The software will not re-triangulate after adding the boundary to fill in the missing edges.  If you really want a TIN line from 222 to 228 then you need to add that after the boundary.

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Posts: 66
Registered: ‎01-01-2014
Message 5 of 11 (276 Views)

# Re: Surface boundary problem

01-09-2014 10:15 PM in reply to: allywhite666

Ok I figured it out, the outside points were causing the triangles to run outside the boundary. So I put a break line round the boundary first then set the boundary. Thanks for the help

.

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Message 6 of 11 (271 Views)

# Re: Surface boundary problem

01-09-2014 10:19 PM in reply to: allywhite666

Another solution which may work better - offset your current boundary polyline slightly, 1-2 cm outside of your intended surface edge, and then apply that new polyline as a destructive boundary.

Steve
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Posts: 66
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Message 7 of 11 (269 Views)

# Re: Surface boundary problem

01-09-2014 10:27 PM in reply to: sboon

@sboon

"

But non-destructive will include all the points outside the boundary.

Nope - The new surface edge will stop at the non-destructive boundary.

"

This will not work you have to put the break line in to make the triangles run along the boundary or it will include the points outside the boundary and distort the contours see below. The circle shows the errors.

non-destructive break lines.

Destructive boundary with break lines.

It smoothed the errors.

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Message 8 of 11 (261 Views)

# Re: Surface boundary problem

01-09-2014 10:38 PM in reply to: allywhite666

Can you post a copy of the drawing?

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Message 9 of 11 (251 Views)

# Re: Surface boundary problem

01-09-2014 10:50 PM in reply to: sboon

No problem Steve.

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Message 10 of 11 (232 Views)

# Re: Surface boundary problem

01-10-2014 12:31 AM in reply to: allywhite666

I wanted to try something else, but that didn't work so I did some messing about to show some other things which can improve your workflow and possibly make life easier in future.

I've added string numbers to some of your points that represent linear features, like fences and edge of roadway.  I edited your Description key and added wildcards to those keys so that the numbers are recognized as part of a legitimate description.

I added your drawing points to survey database and built a Figure Prefix database to create survey figures that connect the points with string numbers.  Unfortunately the FP database doesn't allow wildcards but it's easy to copy and renumber them.  Some of the figures are 3d breaklines, while others build 2d lines only.

If you add string numbers to your field coding then you will be able to "draw" the lines as you work, and you can automate the drafting and surface construction.

Steve
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