Shrinkwrap Cogo Points

[Anonymous]

I have lots of points and need to delineate a boundary from the points. I have been extracting the boundary from the surface and modifying the polyline to snap to the points that were skipped.......Is there an easier way to do this? I have tried the "Maximum Triangle" trick, but that also does not snap directly to each of my bounding cogo points that would be good for my surface boundry.

Thanks in advance!

Scottie

[neilyj666]

Don't think there's an easy way to do this.....presume you are having problems with triangles spanning "concave" areas??

A possible way is to create the surface as normal, then draw a polyline just outside the outer limit of the valid triangles and use this as an outer boundary (or even as a surface crop perhaps??)

[AllenJessup]

I thought I had a great idea. Create point blocks from the cogo points, explode the blocks and use the points for a Lineworkshrinkwrap. A test did not go well. Got some very weird results. Also I had also thought that the PType display was only a display and the point was always just a node. The results I got challenged that idea. See the attached.

Allen

[neilyj666]

I think that LINEWORKSHRINKWRAP needs connected linework (a bit of a clue in the command name) to work correctly...!!!!

Another way would be to extract the triangles and process them down to lines, mapclean to remove the duplicate lines along the common boundaries, erasing the line defining non valid triangles and then shrinkwrapping - but this could be a bit of a chore

[AllenJessup]

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@neilyj666 wrote:

Another way would be to extract the triangles and process them down to lines, mapclean to remove the duplicate lines along the common boundaries, erasing the line defining non valid triangles and then shrinkwrapping - but this could be a bit of a chore

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Don't forget to flatten the lines before shrinkwrap.

[neilyj666]

Glad one of us is paying attention...

[AllenJessup]

Yeah. I remembered that because I'd reread what you posted in creating surface from 3d face.

[neilyj666]

LOL - it's getting late, time to go home...!!!!

[troma]

There are some interesting ideas here, but are any of them actually better or faster than just drawing a closed polyline?

Here's what I do:

1. Build the surface.

2. Turn off all layers exept the surface, set the display to TIN only.

3. Set your OSNAP to Endpoint only

4. Set the OSNAPOVERRIDE system variable to 1

5. Draw your polyline to your heart's content; close when you come around.

6. Set the OSNAPOVERRIDE system variable to 0  (I have a love/hate relationship with it)

7. Put the polyline to zero elevation (it inherits the elevation from the first point you clicked)

8. Add polyline as a boundary.

[AllenJessup]

Very nice. That contains some good Tricks/Tips. For the OP original request to "ShrinkWrap Cogo Points" I'd suggest taking his original method of extracting the Surface Boundary and modifying it. Use your suggestion to use OsnapOverride and set the running Osnap to Node. Then he can quickly modify the polyline extracted from the Surface Boundary.

Allen

[neilyj666]

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@troma wrote:

There are some interesting ideas here, but are any of them actually better or faster than just drawing a closed polyline?

Here's what I do:

1. Build the surface.

2. Turn off all layers exept the surface, set the display to TIN only.

3. Set your OSNAP to Endpoint only

4. Set the OSNAPOVERRIDE system variable to 1

5. Draw your polyline to your heart's content; close when you come around.

6. Set the OSNAPOVERRIDE system variable to 0  (I have a love/hate relationship with it)

7. Put the polyline to zero elevation (it inherits the elevation from the first point you clicked)

8. Add polyline as a boundary.

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Is this not what I said in my first post ?? - although I'll check out the OSNAPOVERRIDE variable

[AllenJessup]

Set OSNAPOVERRIDE to 1. You then cannot pick a point that does not conform to your running osnaps.

So that means that if you miss the Node, Intersection, Endpoint, whatever you won't create a bogus vertex by accident. You can stay zoomed further out and not worry about missing. Just remember to set it back to 0 when your done because if you have the Osnap set to Node and OsnapOverride on, you would never be able to select anything hat didn't have a node.

Also useful - OsnapNodeLegacy

Allen

[neilyj666]

...so this means I won't create an accidental vertex near to one of my endpoints, nodes etc due to overenthusiastic clicking? I wish I'd known of this setting several years ago...!!!!!! Putting this on a right click macro is a good idea

[troma]

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@neilyj666 wrote:

......

Is this not what I said in my first post ?? - although I'll check out the OSNAPOVERRIDE variable

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Hmm...In your first post you said "then draw a polyline just outside the outer limit of the valid triangles".  I'm saying snap to the triagles, not outside them.  But some of us prefer destructive, some non-destructive boundaries, so I won't judge.

The reason I'd snap to Endpoint of the triangles rather than the node of the points is to enure I'm not snapping to points that are not in the surface.  There may be topo that is not included or not suitable for building a surface.  So I've normally got it built from a point group that includes only the points suitable for building a surface.  The easiest thing to draw the polyline to is then the surface TIN itself; if you try by node you could end up snapping to one of the bad points.

[Joe-Bouza]

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@Anonymous wrote:

I have lots of points and need to delineate a boundary from the points. I have been extracting the boundary from the surface and modifying the polyline to snap to the points that were skipped.......Is there an easier way to do this? I have tried the "Maximum Triangle" trick, but that also does not snap directly to each of my bounding cogo points that would be good for my surface boundry.

Thanks in advance!

Scottie

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that sounds odd. Are there other data in the surface getting snaped to? Are you making the surface with only points?

[Anonymous]

I have imported points from a file, then create my surface for only those points. Then extract boundary, then modify boundary by snapping to the nodes. Sometimes the boundary will not conform to the points especially on a concave side, so i have to hover over the vertex and select new vertex, then snap to the node...over and over again until my boundry is the points from file.

[Joe-Bouza]

If you are only using the points, playing with Max triangle is a good start. Then inspecting the perimeter for extra triangle for deletion is required. Tweaking Max triangles should get it very close.

[neilyj666]

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@troma wrote:

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@neilyj666 wrote:

......

Is this not what I said in my first post ?? - although I'll check out the OSNAPOVERRIDE variable

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"... But some of us prefer destructive, some non-destructive boundaries, so I won't judge..."

I suggest it's not a case of preference rather what gets the job done that I am trying to do.....(with the minimum of crashes)...

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[troma]

True.

Generally I prefer a boundary that's absolutely on the outermost piece of data for a topo surface, using the method I described.

Design / Finished Ground surfaces are a different story; I'll often use a boundary that trims the surface to a smaller area, but use a feature line outside of the boundary to build the surface.

BTW, do you like the terms 'destructive' and 'non-destructive'?  To me they are very confusing terminology.  'Trim' or 'Delete' would seem to me to make more sense as options for an outer boundary.