topic Re: How to represent "Platforms" in Civil 3D? in Civil 3D Forum

How to represent "Platforms" in Civil 3D?

soonhui — Fri, 08 Jul 2022 04:05:23 GMT

I define "Platform" as a 3D surface that is a coplanar polygon. Take for example, in a residential area, a road can consists of multiple platforms, lying alongside with the residential platforms ( where houses are built). The residential platforms are "flat", in the sense that all the z coordinates on the platforms are the same.

You can understand Platforms as TIN surface, but there might be drop between edge to edge of the triangles.

Now, how to represent "Platforms" in Civil 3D to the best accuracy? TIN surface is not really suitable, because between the triangles, there can be no drop.

I append a drawing here for illustration purpose. The entities in the both layers "Others" and "Terrain" are platforms according this definition. Note that in between the entities, there can be drop.

So how to properly representing them using Civil 3D level objects like Surface?

Re: How to represent "Platforms" in Civil 3D?

rl_jackson — Fri, 08 Jul 2022 04:09:26 GMT

IMO just a quick look, I believe your OCD is overthinking things. You are using straight ACAD objects (or something) to achieve something that is built into C3D and not using a ADESK product based on my initial open of the file, Try the application your usings forum

Re: How to represent "Platforms" in Civil 3D?

soonhui — Fri, 08 Jul 2022 04:52:22 GMT

@rl_jackson, I don't understand what you are saying. You mean?

I need to represent those Platforms as Surface because I want to do cut and fill between two surfaces. I don't think normal CAD objects can accomplish this goal?

Re: How to represent "Platforms" in Civil 3D?

surafeltklt — Fri, 08 Jul 2022 09:39:28 GMT

I believe its possible to do TIN surface with drop downs but the drawing is not from civil 3d and I did not quit understand it but you could do holes at those areas you called platforms I think we call them building foot prints and on this holes could make a surface defined by 3d lines or points for that mater; the thing building the flat surface in side the hole after that you could add those surfaces using edits to paste the flat surface on the other surface. well to to the dropped part in the tin make another boundary adjacent to section that is on higher elevation and build another flat surface inside the new boundary the paste this surface to the higher elevation flat surface. there could have been many work around to do this if you describe the situation more clearly thank you sir.

Re: How to represent "Platforms" in Civil 3D?

soonhui — Fri, 08 Jul 2022 09:48:30 GMT

@surafeltklt, yes, the drawing is not from Civil 3D ( it's from AutoCAD).

My task is to convert the entities on the two layers: "Others" and "Terrain" into one TIN Surface. This is a challenge because

it contains drop ( eg: there are edges/points that have the same {x,y} but different z), which I am not sure whether Civil 3D TIN surface can handle?
I need to preserve the original lines and triangles.

I can relax the second condition if it's not possible for Civil 3D to do so.

Re: How to represent "Platforms" in Civil 3D?

surafeltklt — Fri, 08 Jul 2022 10:14:22 GMT

I think civil 3d can handle it. just try the work around I mentioned earlier

How to represent "Platforms" in Civil 3D?

ChrisRS — Fri, 08 Jul 2022 15:35:01 GMT

The internet ate my reply.

I do not have time to recreate it.

Short version.

You have a drawing that was created by non-Autodesk third-party software.

"Platforms" are not AutoCAD or Civil 3D objects.

The surfaces you are interested in are represented by meshes.

You can explode meshes to 3d Faces, then add those to a Civil 3D surface.

Link: Creating-Surface-from-3D-Faces

To get Volumes, you need overlapping surfaces. Use Original Terrain and Others.

Revised File Attached.

Good luck,

Chris Stevens

Others

Original Terrain

FG Paste in Original Terrain, then paste in Others.

Re: How to represent "Platforms" in Civil 3D?

surafeltklt — Fri, 08 Jul 2022 19:51:40 GMT

1st convert the mesh to tin then follow this procedure I believe its possible to do surface with drop downs. you could do holes at those areas that you want create flat surface and you could make the flat surface defined by 3d lines or points for that mater; the thing is building that flat surface in side the hole; after that you could add this surface using edits to paste the flat surface on the other surface that could be existing ground. well about making the dropped part in the flat surface make another boundary adjacent to or on the middle of the flat area and build another flat surface inside the new boundary the paste this surface to the bigger surface.

Re: How to represent "Platforms" in Civil 3D?

Joe-Bouza — Fri, 08 Jul 2022 19:19:21 GMT

In Civil3d each Platform has to be its own surface to prevent triangles from dropping

Re: How to represent "Platforms" in Civil 3D?

sboon — Mon, 11 Jul 2022 21:33:54 GMT

If you only want to calculate volumes between the Original ground and the Others surface then there is no need to combine the two data sets. I did pretty much the same as others - exploded the meshes to get 3d faces and then used them to build two surfaces. After that I can calculate volumes as shown below. The software will create a vertical boundary at the edge of the Others data where the two surfaces have different elevations.

Re: How to represent "Platforms" in Civil 3D?

soonhui — Tue, 12 Jul 2022 02:57:16 GMT

@Joe-Bouza , what do you mean by

@Joe-Bouza wrote:
In Civil3d each Platform has to be its own surface to prevent triangles from dropping

Are you saying that inside a Surface, there can be no two vertex with the same {x,y} value, but different z values?

Re: How to represent "Platforms" in Civil 3D?

soonhui — Tue, 12 Jul 2022 03:18:33 GMT

@surafeltklt , can you show me an example drawing of a surface contains drop ( ie: vertexes that are the same in {x,y} value but different in z)? Thank you!

There is a good reason I think that Surface in Civil 3D can't support surface drop, because the FindVertexAtXY Method can only return one point, and not multiple points. What is the documented behavior for Civil 3D on this?

Re: How to represent "Platforms" in Civil 3D?

sboon — Tue, 12 Jul 2022 04:08:36 GMT

Civil 3d and pretty much every other piece of software used for building terrain models uses the Delauney algorithm. That algorithm can only accept one elevation for any X,Y point.

If you Google "Civil3d wall breakline" you can find a tool that allows you to create a close approximation of a vertical face.

Re: How to represent "Platforms" in Civil 3D?

rl_jackson — Tue, 12 Jul 2022 05:15:03 GMT

@Joe-Bouza is saying exactly that. A TIN can not have the same x,y,and z at the same x,y there must be a slight shift no matter how minute. You cannot have a "vertical" face in a TIN model".

Re: How to represent "Platforms" in Civil 3D?

surafeltklt — Tue, 12 Jul 2022 14:55:54 GMT

yes, there can't be two points with the same xy and different z within the same surface or same triangulation; that's why you have to do two triangulation one for dropped flat surface the other for the remaining flat surface.

Re: How to represent "Platforms" in Civil 3D?

Joe-Bouza — Tue, 12 Jul 2022 17:15:17 GMT

not exactly but this is the case.

I am answering your question specifically; there can be no drop. a separate surface is the only way to do that

You can understand Platforms as TIN surface, but there might be drop between edge to edge of the triangles.

Now, how to represent "Platforms" in Civil 3D to the best accuracy? TIN surface is not really suitable, because between the triangles, there can be no drop.

I append a drawing here for illustration purpose. The entities in the both layers "Others" and "Terrain" are platforms according this definition. Note that in between the entities, there can be drop.

Re: How to represent "Platforms" in Civil 3D?

surafeltklt — Tue, 12 Jul 2022 18:49:16 GMT

you must have get me wrong sir; I did not say that you can have a surface containing the same xy and different z sir if u have read my first comment i say use two surfaces one for dropped part the other for the remaining flat part then paste then to create one single surface that's to avoid this issue.

Re: How to represent "Platforms" in Civil 3D?

soonhui — Wed, 13 Jul 2022 01:20:54 GMT

@Joe-Bouza , your drawing is missing....

Re: How to represent "Platforms" in Civil 3D?

soonhui — Wed, 13 Jul 2022 01:40:25 GMT

@surafeltklt , sorry for the misunderstanding ! Can you attach a drawing to illustrate your point?