how to create 3d terrain from contours

[cjstrom15]

hello, i am trying to create a 3d solid from a file with contours i have. this file is attached below, and also has elevation points, buildings, and water. only the contours have an elevation yet, and that's all i need for now, but i can't figure out why i can't make a solid terrain. i have access to autocad educational, but no other autocad options.

i have tried using the loft command, and then thickening the mesh, but i get an error 114066 code. 

i have tried using drape command, but i have autocad educational, and it does not exist (command not found).

i am trying to get what i have (in the file), to look like the image i also attached below. any advice or help for autocad educational would be appreciated, thanks!

[R_Tweed]

Were you able to get as far as a surface mesh?

[cjstrom15]

no, thanks for responding, but when i try the loft command, it says error 114066, and cancels action. i cant get any sort of mesh, cant create a surface, and it wont create any sort of solid terrain. any suggestions?

thanks again.

[R_Tweed]

The error code is from the lofted surface wanting to self intersect.  A different approach can be used that will accommodate all the switchback contour lines using a network  <<here>> .   You might want to also consider creating a solid of the area where detail is needed and use a different mesh creation method for other areas.  The attached lsp routines can be used to create a 3d face network. 

[cjstrom15]

hello again, i'm not intirally sure what you mean. i have checked the model, and no contours intersect, or overlap.
also, what do you mean by creating a solid? i don't know how to do that, what i have done so far it outline the model edges, but nothing changes.
any suggestions?

[dbroad]

The contours may not self intersect but successive contours are overlapping and don't make sense, especially at ditches. There needs to be a lot of fine tune editing of moving verticies to logical locations relative to one another to make them workable to turn into a solid IMO. You would need also to select the contours in the correct sequence.  That, itself would be quite a challenge with so many.

[R_Tweed]

For future readers using ACA. Drape would be the command to use in this situation. the use of guide lines in valleys and ridge will be helpful to create a better surface drape. That said, the ending solid in the method below can be converted to a mass element if editing is needed. See ridge lines and sharp valley areas in the attached model.

I'm not sure how to explain the issues with lofting contours that are not somewhat uniform. The picture below shows two simple lofts and the effect of variation in the profiles or contours. When contours overhang or have abrubt elevations, sharp returns lofting will fail.  I don't believe you will be able to create a lofted surface from the contours as shown without a considerable amount of editing and preparation.  See below for alternate method.

The following method has been automated to a high degree with programs like C3d.  The lsp routines provided in the previous post will "help" in developing this type of surface. The first routine will place points at each vertex of a polyline there are additional lsp routine on the web for refining or adding additional vertices to polylines as well.

The second routine will place 3d faces as a network of triangles connecting the points. This is a TIN or Triangulated Irregular Network.

Once you have a triangulated surface, some editing will be needed to adjust the orientation of triangles particularly along ridges and valleys.

If you want a solid object,  use CONVTOSURFACE to convert the faces to surfaces.

Create a boxed surface with bottom and sides to enclose your surface.

Use sculpt to convert to a solid.

I've attached a portion of your file for reference.

[cjstrom15]

thanks for clarifying, i will try these ideas. ill report how it goes, and we could work from there. thanks again!

[cjstrom15]

hello again, i cant figure out how to import the lisp files, maybe im not doing it right. autocad repeatedly inserts the text into the drawing. what button do i hit to get the lisp to run?

also, i think it might help if you have the entire story for my project. i started with a pdf of the terrain, attached below, and am trying to get a solid surface that i can export in a stl file for 3d printing. i already have shown you the file so far, attached again below, with contours, water features, and buildings. 

based of the videos i have seen, and my knowledge of autocad, i should be able to create a solid using what i have already, right? 

[R_Tweed]

You can load a lisp file by to dragging the file from windows file explorer to your autocad workspace.  Yes,  the steps above will generate a solid model which can be saved as an stl file using 3dprint.  The previously attached zip file has a solid model that you can use for testing.

[cjstrom15]

hello again, just one more question. how are you making the surfaces, in the picture above, that are orange? i have the terrain surface and its solid, but i cant figure out how to get the sides to become solid like you have it. any suggestions? thanks.

[R_Tweed]

Create a surface and then extrude as a surface. (see mode)  Then use sculpt to convert to solid. Hopefully the attached video will show up.