how to convert a building model into a solid object for 3d printing

[Allen Brown]

Title says it all "how to convert a building model into a solid object for 3d printing". Trying to make a mass model of just the exterior face of a building, image attached. Converted to mesh, generic object, nurbs and combining, stitching, closing, etc.  I've tried the model commands, adding, subtracting, intersecting with a cube, etc. Also tried make solid with Meshmixer with disastrous results. There should be a relatively easy way to do this that I'm missing! 

[BartH]

Hey, Allen.

There is a whole other subforum for 3D printing, check it out:

https://forum.vectorworks.net/index.php?/forum/42-3d-printing/

 

In my experience, it isn't as simple as you would think. VW models are composed of many types of geometry. In 3D printing, overlapping geometry are often seen as hollow spots. 

What you might be looking for is a watertight "shell" that wraps all of the geometry tightly, ignoring everything inside the shell. 

VW doesn't have the tools for that. But other apps can do it. Meshlab is amazing if you can figure out the interface.

Blender has a Voxell remeshing modifier that might do it for you, as well as some other plugins that might help

 

The only other option is to rely on the Slicing software to recognize holes in the model and try to fix all holes.

 

Bart

 

 

 

 

[Allen Brown]

I've downloaded Meshlab and imported the model; any tips on the interface?

 

[BartH]

Hey Allen,

 

I've been experimenting over the weekend. Unfortunately, Meshlab doesn't seem to be good for hard-edged things like architectural models. 

 

I've found two techniques that help with cleaning up models for 3D Printing.

 

A) Use a meshlabs filter to remove points inside the mesh with an Ambient Occlusion filter

B) resample a point cloud over the surface of the model and create a new surface with a Screen Poisson reconstruction

 

The reality is that the geometry from VW makes both of these tricky. 

The Ambient Occlusion process struggles with close together points, like the glazing, and wants to remove them.

The Poisson reconstruction works great on organic shapes but wants to smooth edges quite a lot. bad fro architect.

 

Here are the general steps

 

Ambient Occlusion culling:

1. Load the model into Meshlabs
2. Use Filters> Color Creation and Processing>Ambient Occlusion. Use the default setting
3. Use Filters>Selection>Select Vertex by Quality> Check the Preview tick-box
4. Adjust the Max Quality slide down so that all of the interior vertices are highlighted, leaving the exterior points in tact.
5. Hit Apply and Close, to close the dialog.
6. Use the Delete Key to remove selected vertices.

Repair errors:

1. Filters>Cleaning and Repairing>Repair Non-Manifold vertices by splitting
2. Filters>Cleaning and Repairing>Remove Unreferenced Vertices
3. Filters>Cleaning and Repairing>Repair Non-Manifold Edges (You might run these 2 or three times)
    

You will have removed all vertices that are "inside" the outer shell. Unfortunately, this also seems to remove the glazing because those corner points are "hidden" inside the walls. 

 

Close Holes

1. Filters> Remeshing, Simplification and Reconstruction>Close holes
2. Adjust the hole size parameter until all holes are filled. 
3. Repeat as needed.

I think this will get you as close as possible. The more you can do in VW to make a solid model, will help.

 

There is an "Alpha Wrap" Filter under Remeshing, Simplification, and Reconstruction, which should "Shrink-Wrap" a new mesh over your model. 

In my brief experimentation, it does well with organic shapes and struggles with models that have large flat planes with tiny details ( like windows in walls).

I'll try a few more tests and let you know if I get a better Process.

 

Bart

 

 

 

Edited April 20 by BartH
Typos

[Allen Brown]

I’ll give it a try! Appreciate your help..

[Allen Brown]

Couldn't get decent results but probably operator error. The Alpha Wrap is promising but also nada. I've uploaded the obj file if you want to work with it. -AB3111.obj.zip

[BartH]

OK, I've had some luck.

 

Running the Alpha Wrap filter with the Alpha setting at 0.06%, I get a reasonable result:

 

It took 30 minutes to run on my machine and generated a model with over 5 million faces.

Using the Filters>Remeshing, Simplification and Reconstruction> Simplification Quadratic Edge Collapse Decimation> with the percentage set to 0.25 I get a model closer to 1.3 million faces as seen above ( this took several minutes, too)

Model attached. Depending on the scale you print at, this might be Ok. 

3111 Reduced.zip

[Allen Brown]

Impressive! But still hollow..

[Allen Brown]

14 hours ago, Allen Brown said:

Impressive! But still hollow..

To clarify, as the scale is reduced, the windows disappear and interior is visible and hollow. Here's a screenshot from orcaslicer at .5 scale showing supports (interesting none for the pitched roof). My intent if I can generate a solid object is to then cut into three sections to eliminate supports then glue together. 

[BartH]

Odd, I really thought this would ignore the interior faces, but it didn't.

Here is a test using the Ambient Occlusion mapping to remove interior vertices. See if that is better.

 

Out of curiosity, what slicer are you using? There might be an option in there to disable "Union overlapping volumes."

3111 Reduced R2.zip

[Allen Brown]

That seemed to do it! Here's results from orcaslicer and Bambu studio. I'll look for the option also.

 

[Don Seidel]

We print on a base model Bamboo 3D printer. No difference between STEP or STL export that I can remember (your mileage may vary).

 

of note: VW doesn't export doors or cabinet faces with panels well for 3D prints. We have to first thicken door panels and window sashes, then convert these objects to mesh. Successful print, usually with a void where glass is, but that's fine with me/ us.

Obviously, details are scale-dependent. Some railings just too small to print, and look funny if we fatten them enough.

[Allen Brown]

32 minutes ago, Don Seidel said:

We print on a base model Bamboo 3D printer. No difference between STEP or STL export that I can remember (your mileage may vary).

 

of note: VW doesn't export doors or cabinet faces with panels well for 3D prints. We have to first thicken door panels and window sashes, then convert these objects to mesh. Successful print, usually with a void where glass is, but that's fine with me/ us.

Obviously, details are scale-dependent. Some railings just too small to print, and look funny if we fatten them enough.

Thanks for tips! Since the post, per BartH, I've been able to create "mass models" by "shrink-wrapping" the exported OBJ mesh using MeshLab (although it generates millions of triangles) then printing on a Bambu P2S. Do you have a more direct method? Attached a photo of a few models..

[Don Seidel]

we don't do any post processing after VW export. We live with the limits in that process. (I have posted bugs that paneled doors and cabinet doors don't properly export to STEP or STL), and what modifications are practical. We have done a 32" (actual length) long house model by slicing VW copy into 5 models before exporting.

[Allen Brown]

Looks good! I'll have try one at a larger scale. How do you support the floors during printing?