How to Delete Higher of Two Surface Points?

[Anonymous]

The scenario: I was given a datum tin surface (no feature lines or CRDR) and I need to trim areas up in order to merge it into another surface. The issue is at the curb & gutter locations where the datum surface goes from bottom of subgrade to top of curb in the shortest of distances, so unless you really zoom in, the two points are effectively on top of one another. Picture a section view, the surface is shaped like an L. I need to delete that top of curb point so I only have bottom points. The two points are so close together it would take me forever to manually zoom into each triangle, pick and delete the top point. The curb and gutter offsets vary as well, so I can't create an offset polygon and use as a surface boundary. Any ideas?

Thanks,

RJ

C3D 2016

[Anonymous]

Could you post the file and some images highlighting what you are after

[Anonymous]

Hi Ian,

Thanks for responding. Attached is a screen shot of a partial section. Circled in blue are the points I want to remove. The two green lines I added represent the surface I need between curbs in this scenario.

RJ

[AllenJessup]

The distance has to be >0. Call it X. Can you create a Featureline defining the top of curb and offset it 1/2 X? That way you could use it as a Surface boundary an paste the one Surface into the other.

[Anonymous]

Allen,

That would work on portions of my surface where the curb defines my outside limits; however, what would you suggest for a median situation as my screen capture shows (attached in my second post)?

Thanks,

RJ

[AllenJessup]

Hello RJ. I read it as paste the green surface into the red surface. If the green surface doesn't extend far enough. I'd create a FeatureLine for bottom of curb, offset it a minor distance and add it to the green surface.

[Anonymous]

Sorry, I should me clarify. The green lines represent the changes in the red surface after removing the top of curb points. Actually, I need to past the red surface onto the yellow surface, after removing those points. Unfortunately making feature lines at the bottom of curb isn't feasible (as far as I know?) because curb offsets vary and all I was given was a TIN so I cannot extract feature lines from a corridor.

[AllenJessup]

Does the surface contain any breaklines you could insert into the drawing?

[Anonymous]

Unfortunately no, there are no breaklines in there. I was only given an XML of the surface.

[Joe-Bouza]

if the green line in your image is the surface you want to paste together, you can first create a volume get the 0 contour in the fill areas then you'll have polygons to trim the erroneous triangle

[Joe-Bouza]

Another option is to call the corridor person and ask for the correct datum surface

[AllenJessup]

Hopefully @Joe-Bouza's idea will work. Otherwise I can't think of anything else. I tried to tip a Surface into 3D so I could differentiate the top of curb from the bottom. It looks like Civil 3D doesn't recognize Surface points if the view is 3D. See my post: 

Can't select Surface point in 3D view 

[AllenJessup · Accepted solution]

I have found out that you can tip the surface up and select Surface points to delete. There was a problem with the drawing I was testing it in.

This is a very attractive method of doing this. But you can differentiate top of curb from bottom. Hopefully something better comes along.

[AllenJessup]

You might try to Simplify the Surface. Set a Maximum change of just over the largest curb height. It might be an iterative process. I've never used it myself. So I'm just guessing.

[TerryDotson]

This has been added to C3DTools as Surface Point Delete, Relative option.  Prompts for a horizontal and vertical tolerance along with which point to keep (high or low).  Existing users simply run Check for Updates.  Any other way to logically delete multiple points on a surface let us know.

[ACADuser]

The unwanted points can most likely be removed using MS Excel to manipulate the data.

[Anonymous]

I probably shouldn't have included the green lines as it didn't add clarity. The green lines represent the change in the red surface in between the curb points after the top points are deleted. It is not a surface.

Joe - The volume surface zero-contour tact is a clever one, but it just doesn't apply here. I'm gonna keep that one in the back pocket though! I ended up taking your second suggestion and got a hold of our client and they're going to try to get the corridor file.

Allen - If above doesn't work, I'll do as you suggested. Crossing my fingers that I won't, but it sure beats the alternative! Thanks for checking that avenue out for me.

Thanks again,

RJ

[AllenJessup]

I don't blame you for not wanting to take that course. It's just a port of last resort, so to speak. If you can get the corridor or featurelines or even polylines it would be much better.

As @ACADuser mentioned. You could export the points and write a formula in Excel to remove them. But that would lose the triangulation. Recreating the Surface from points without breaklines might yield strange results. But it's a possibility.

[Joe-Bouza]

Good luck RJ
It should be quick and easy for them.
They may need to add a generic link under the c&g but no biggie

[Anonymous]

Well, I ended up having to do as Allen suggested; rotate the surface to a 3D view and manually delete the points. It wasn't as bad as it could've been. One thing that I did that really helped differentiate the points I wanted to delete was this: in Surface Properties / Analysis / Slopes, I set it to have two bands - 1<200%, 2>200% slopes - making the flat slopes a very dark gray, while setting anything over 200% to be red. With this visualization, I was able to easily spot my near-vertical faces and rotate my view at angles where I could delete many points in one swipe.

Thanks again for all of your suggestions!

-RJ