Cropped surface issues with object selection

[Buzz0m]

Hi there,

I'm trying to crop my surface with a polyline but with no success. Here's what I've tried:

1. Create cropped surface
2. fill in necessary fields (the "new surface"-section of the dialogue) for creating a cropped surface in an existing open drawing.
3. Select surface to crop (the "crop information"-section of the dialogue).
4. Select crop area: I clicked the "..." symbol and the hit O for object, select my polyline and click inside of the closed polyline
5. I get the error message: "invalid boundary selected"
6. Curse a few times
7. Repeat steps 1..5
8. Curse some more
9. Look for help on AD forums...

The surface is not referenced. I've tried simple rectangular polylines as cropping objects. If I use polygon or window as the selection method for the crop area everything seems to work.

I would also like to know wether or not it is possible to make the cropped surface dynamic as a data shortcut reference?

I'm grateful for all tips!

[jmayo-EE]

"invalid boundary selected"

Your polline boundary has issues. Bow-tie overlaps from daylighting, puesdo/null nodes, etc...

Take the boundary. Force it closed and try to use the BOundary command to recreate a new one.

If this fails explode the pline, start MapClean or OverKill and begin to clean up the linework. With MapClean you can break crossing objects, delete duplicate objects, combine colinear lines, and more.

[Buzz0m]

Thanks for the tips!

I tried most of those things on my original boundary but to no avail.

I also tried drawing a simple rectangle and using that as the cropping polyline... still got the error...

[doni49]

Just for kicks instead of just drawing a rectangle that you will later try just drawing the boundary by points (when prompted to choose points or enter O/P, pick points).  Will it let you crop your surface now?

Check to be sure the polyline really does close.  When I tried to recreate your issue, the ONLY way I could generate the error you're seeing is by breaking the rectangle so there is a gap.

If all this fails, post your dwg file and someone will take a look.

EDIT:  I forgot to ask what version you're using.  I have 2012 and 2014 installed here -- I did my tests in 2014.

[Buzz0m]

drawing the boundary with the polygonal option ("boundary by points") and window works in my drawing. And the rectangle polyline I mentioned in my previous post is closed and non-overlapping.

What I'm trying to accomplish is divide my surface into 3 separate surfaces (stages of construction) and save them all in one drawing. I want to be able to edit where the surface is divided (that's why I've been trying to use the object selection method hoping that if I change the object in the future the cropped surface boundary will change. To my dissapointment I'm starting to think that cropped surfaces do not retain any relationship to the original surface or drawing whatsoever?! This would mean that I will not be able to update the cropped surfaces as one does with data shortcuts?). The original surface might also change so an optimal solution would be a dynamic link between the original surface and its 3 cropped parts.

I know there is one obvious solution: why doesn't he just use 3 surfaces? I could do that but the border areas between the 3 surfaces would need much work and tweeking each time I change the design and I'm not that fond of doing alot of extra work 😃

[doni49 · Accepted solution]

Take a look at the attached dwg (I did it in 2014 -- hopefullly you can open it).

I have an EG surface.  Then I created three FG surfaces and pasted EG into each one.  Then I drew three rectangular polylines and used each one for one of the FG boundaries.

I think this should accomplish what you're looking to do.

P.S. You're correct that the cropped surface doesn't maintain a link back to the source surface.  The method I've outlined above WILL.

[Buzz0m]

Thanks for taking the time to do the attached dwg! I've never used the paste surface option before! That is exactly what I need! Props to you, Doni!

[doni49]

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@Buzz0m wrote:

Thanks for taking the time to do the attached dwg! I've never used the paste surface option before! That is exactly what I need! Props to you, Doni!

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Yeah when I first started working with C3D, a co-worker showed me the paste surface option and I KNEW that would prove useful and it has on many occasions.

[jmayo-EE]

Thanks for picking up the slack Doni.

Just note that although the method is smack on and works perfectly the reality is that you carry the entire surface definition in each of the three surfaces and simply hide the extraneous data with an outer boundary. No an ideal situation for a large dataset...

If cropped surfaced or data clip boundaries worked as expected with DRef's (as the OP was hoping to do) you would have the benifit of smaller surface definitions....

[jmoellering]

I have a surface I want to make several holes in.  First try worked fine, but when I tried to do all of them, I got "Error creating cropped surface".  Turns out the first hole happened to touch the edge.  It appears that when cropping, the new boundary must be contiguous, no isolated holes inside a larger surface.

[amonsour]

WOW! I just spent an hour trying to figure out why my polyline was saying "invalid boundary selected".  It was closed, put at elevation 0, tried adding as a boundary in my surface...restarting AutoCAD, trying other versions of AutoCAD.  I kept thinking, "I've done this SO many times before and never had this issue!".  

Yeah, make sure you're in USC World, friends...don't be like me.  

[Buzz0m]

That is definitely something I'll remember next time I run into that issue! I can't say I've heard about that issue before but thanks for mentioning it, @amonsour !