Modeling a terrain as a solid (not a mesh) in Autocad, with a smooth surface

[teocruz105]

Hi. I've been facing problem creating a solid 3D terrain in AutoCad. I'm using DRAPE to create a mesh from curve level. the Mesh looks great. But I need it as a solid. So when I convert it to a solid, the surface looks really bad. I need it as a solid to edit it as such, and the then to export it to STL. The stl file will look as bad as the solid. Does any one know a procedure which allows me to creat a decent solid terrain in AutoCad as solid? I posted this question here some weeks ago( https://forums.autodesk.com/t5/autocad-forum/modeling-a-terrain-solid-not-a-mesh-with-a-soft-surface...

and I received good adviceces, but the issue is not solved yet. I am attaching a file that can better explain what I'm talking about.

[j.palmeL29YX]

In the LISP above I forgot the underscore, please correct to 

(command "_pline" p1 p2 p3 p4 "_c")

(if you use a non English AutoCAD version).

Sorry ... 

[Anonymous]

Hi 

Thank you for your input. But i find it difficult to make buildings solid with what you have suggested. Can you try for the file uploaded below. And please do send me the video also.

Thank you

[Anonymous]

HI

I could not follow after appload as some library box opens up for me instead of mreg.pa. Can you guide me further and would be nice if you could send me a video along with the file of following dwg file.

thank you

[j.palmeL29YX]

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@Anonymous wrote:

HI

I could not follow after appload as some library box opens up for me instead of mreg.pa. Can you guide me further

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First unzip the mreg-pa.zip and save the file mreg-pa.fas anywhere (e.g. in a folder c:\MyLisps) on your computer. Then start the appload command, navigate to the folder c:\Mylisps, select the file mreg-pa.fas and pick the Load button. You should see a message, when the file was loaded successfully. (the corrected mreg-pa .fas I will attach here).

Now you can run the mreg-pa command. 

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...  and would be nice if you could send me a video

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The video is linked in post #40

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...  along with the file

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No the result file I will not post. You should create it yourself 😉 

Good luck. 

[j.palmeL29YX]

Using your first posted model "Downtown 1-0002 - 3D View - 3D View 1.dwg" [Post #38] all worked perfect as I described above and I got the here attached result "Downtown 1-0002 - 3D View - 3D View 1_Solid buildings.dwg". 

Trying the same with your last posted model "Downtown 1 - 3D View - 3D View 1.dwg" [Post #42 and #43] I see after exploding the block reference twice, that there are some 3DFaces less (38.289 vs 38.281) ond of course less regions. I did not compare which modifications you did (I think you know better what you changed). The annoying consequence: While modifying the file you damaged or deleted one (or some) Polyfacemeshes in a manner, that one or some important 3DFaces (and consequently regions) were lost. So you don't have a watertight model anymore,  which can not be converted to a 3DSolid.  

Either you use the attached dwg  (a successful created 3DSolid) or you check your modifications and repair it to maintain a watertight model. 

[j.palmeL29YX]

After a second try I got the attached successful result. (I'm not sure why my first attempt failed). 

HTH

[j.palmeL29YX]

@Anonymous 

Could you solve your problem in the meantime? Or do you need further assistance? 

[Anonymous]

Hi

i have not been able to generate a model that works fine in the cfd tool simcentre star cmm+. I have no idea of where the error is now as the buildings were solid initially in the first model i posted here. Now when larger area is considered the model has buildings that are not solid. Even after following mreg.pa, the model when imported in simcenter has only few buildings not all the buildings. I tried to convert the original file to stl format and now all the buildings are imported and it seems they are not solid. Will you be able to convert all these buildings to solid. Also the box does not give solid terrain when imported in simcentre. I have here with attached rvt and auto cad  file if you would like to see it.

 Thank you

[j.palmeL29YX]

I'm not sure if I understand your problem. Do you have problems to create the "building"Solid in AutoCAD or does the problem occur after sending the AutoCAD file to your "cfd tool simcentre star cmm+" (whatever that is)?
If the last is correct (and you have a correct Building solid in AutoCAD), then you must search in cimcenter what causes the problem.

If you can not create a solid in AutoCAD - I posted you a file "Downtown 1-0002 - 3D View - 3D View 1 _ Solid buildings.dwg" (post #45) and a "Downtown 1 - 3D View - 3D View 1_ 3DSolid.dwg" (post #46).

Is your last posted "model to be made water tight and solid 3d.dwg" (post #48) a third, new version of your model? After a first quick look I can not see any differences to the file which I posted in #46, but of course I did not check all dimensions. If it is a new one and you have problems creating the solid model I can try it again. But before I must be sure that you need it, it is a time consuming job. 

[Anonymous]

hi 

can you try to make this imported buildings and terrain to solid. even for terrain box command wont help as it will be empty inside when box is used. This buildings are imported today only.

[Anonymous]

When the model is not complete solid this happens in the cfd tool. surface repair tool does not help me in simcentre so my intension is to get complete solid model in autocad. Can you try to create complete solid model for the dwg file posted here and also terrain(not by using box tool).

[j.palmeL29YX]

Unfortunately you don't answer my questions. 

Here again: Can you use the solids which I posted above (post #45 and #46) successfully in your app simcenter or not?  

[j.palmeL29YX]

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@Anonymous wrote:

When the model is not complete solid ... 

Can you try to create complete solid model for the dwg file posted here and also terrain(not by using box tool).

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I don't know what you still need or want. 

In >>this video<<  I show you how to create a terrain solid. 

In >>this video<<  you see, that your buildings are already solids. What still do you want? Of course you must explode the block reference to get the solids (I don't know if if you application can read and handle block references). And if you need ONE solid, you can union all building solids to one. 

But this all has been already shown and said (written) above. 

If your app has problems to read this solid you must search there what causes this behavior. It is not an AutoCAD problem, here is the wrong forum for that. 

[Anonymous]

hi

I have finally managed to create a model that works fine for me in running a CFD simulation in simcentre star ccm+. But the problem is now for few buildings that i have edited in civil 3D. I have few buildings floating (having different elevation). I have really little idea on managing elevation in civil 3d. Can you suggest me some idea regarding this. I have herewith attached my civil 3D model.

Thank you

[j.palmeL29YX]

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@Anonymous wrote:

I have finally managed to create a model that works fine for me ...

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How did you do it? Didn't noone of the postings above help you to find a solution for your issue? 

Your current problem: 

In the plain AutoCAD you can - after setting SUBOBJSELECTIONMODE to 3 - grab the upper face of a building (or some faces at once) and drag it to the needed height. Either you know the difference (example_1, e.g. difference to the current height = 10000)) or you need a given height (example_2, needed height =20000).

>>video<<

If you need or want to use a Civil 3D tool you should ask in the appropriate >>Forum<<. 

[Anonymous]

Hi

I think i  didn't explain the problem well. I have some floating buildings in the model which means they do not have same ground level. Clarity of the problem can be found in the picture uploaded. 

I have learned many things from what you have posted above but to be honest i have not got what i was looking forward to with the model in cfd tool. Mnay buildings are missing in CFD tool even after converting to the solid following your guidelines. So finally i have extruded this model individually using civil 3D.

Thank you for being really helpful

[Anonymous]

hi the picture is attached here

[j.palmeL29YX]

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@Anonymous wrote:

I want to convert traingualted polymesh terrain to solid in autocad as it is disregarded in CFD simulation tool simcentre star ccm+. Can you please suggest me steps to convert terrain to solid of the following model.

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That was your main question. 

In the following postings above several times was explained and shown, how to get the wanted 3DSolid(s) in AutoCAD. 

If your CFD tool has problems reading this solids, you should ask in a forum where "CFD people/spezialists" hang out. 

Here we are in the AutoCAD forum and at the AutoCAD side we can do nothing else but creating valid 3DSolids (as shown). I'm sorry. 

[Anonymous]

I totally agree with what you have said. Thank you for all those guidance. Can  you suggest the way to bring all the buildings to a same ground level for this model. I have done it but i am not sure wether they all are at the same level or not. I tried to move every buildings individually to the same level.

[Anonymous]

And how do i accept your solution just let me know i will accept them all.