Surface boundaries and pasting....hurting my head

[troma]

One large surface.

Pasted into multiple smaller surfaces; made smaller by adding outer boundaries.

The smaller surfaces are adjusted by using the Raise/Lower edit.

Make a new surface.  Paste all the small surfaces in together.

Now, I notice an area that was not included in any of the small surfaces, but was part of the original large surface.  Somehow, this area is showing up in my final surface.  Any suggestions on prevention or removal of this?  So far I tried adding the polyline that forms the 'outer' boundary of each small surface also as a 'data clip' boundary, but don't see any difference.  Only thing that works is delete surface point...click, click, click.

Going home now.

Thanks for all advice.

[MikeEvansUK]

Have you left a gap of say 0.5m (3" in old money) between the boundaries?

Have you draped & added the boundaries as a breakline definition in the "master" surface. If not this may be the problem.

Just clutching at strings really as it could also be the order of surface selection.

M.

[Neilw_05]

I've run into a similar situation some time ago. I used a hide boundary to fix it.

[troma]

Half a metre is roughly 20" as far as I remember. My gaps vary from close to that up to 90m in one spot. What does editing the "master" accomplish?

[troma]

I don't really want to hide the gap. I just want it to triangulate from one area to the next. In one spot I need to add some feature lines to it, so I don't think the hide boundary will work....or will it work if I use the hide boundary first and then add the FLs afterwards?

[Neilw_05]

In your original post I didn't discern you had a gap. I took it to mean you were getting unwanted triangles. I don't think a hide boundary applies in this case so I don't have an answer.

[troma]

Where there should be a gap, or where the TIN should be trinagulating straight across an area, unwanted data is showing up.
I tried a hide boundary. I added it to an area and then added feature lines to that same area. No go: the unwanted data showed up again when I added the feature lines.
I worked through it erasing surface points. That worked anyway.

[MikeEvansUK]

Have you got a picture or a file I can look at pls? Hard to help trying to work it out in my head.

[Neilw_05]

Since you've raised and lowered the various subsurfaces you will need to treat the edges like walls, meaning there has to be a slight offset between the boundaries for triangles to form between the boundaries. Too you'll want these boundaries to be breaklines for the triangles to form. Thus I think you'll need to somehow take all the subsurface boundaries, turn them into breaklines and slightly offset them, then add them all to a composite surface (rather than pasting the subsurfaces) to get the desired results.

P.S. I was wrong about not pasting the subsurfaces. You'll have to do that to get the subsurface triangles inside the boundaries. Will have to think about this some more.

[troma]

I appreciate the help guys. Right now I'm under the gun, but I'll work on getting a picture to you so you can see what's going on.

I do have gaps left between the surfaces. But some of the old data was showing up in the gaps. Basically.

[Neilw_05]

I suspect the problem you are seeing is related to using the same base surface in all the subsurfaces. The software is probably having issues resolving the merge between the boundaries in the composite surface which may be why the base surface is showing up.

[Neilw_05]

What happens if you extract all the subsurface boundaries and add them as breaklines to the composite surface?

If you end up with triangles forming across the subsurfaces, you could try making a surface from the boundaries as breaklines and pasting it into the composite surface BEFORE the rest of the surfaces.