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Phil5635

Painting a sculpt for 3D printing

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Hello,

I’m new here, otherwise a bit old. I’ve been producing some reasonable simple sculpting results in 3DC v4.8 and prepared a couple of files as STL’s to send to Shapeways. Those have been straightforward, single-colour prints.

Now, I have a sculpt to which I’d like to add colour and then send off for Shapeways to print in full colour.

The story so far:

I made a precise but simple shape in Rhino, which I then imported (STL) into 3DC to add lumps and bumps by sculpting;

then, I’ve tried to find a way to add colour in the form of a speckled granite rock. I did have a go at manually painting using the 3DC brush or airbrush, but that really doesn’t work. Now, Shapeways comment that they cannot produce surface colours from “procedural colours/textures” which I assume to mean Smart Materials in 3DC, (no colour showed up outside 3DC);

there’s plenty of bitmaps around showing the sort of rock that I’d like to “paint” onto my model (even a few in my Genetica free viewer), but I have so far failed to discover how  – or even if – I can import and use a colour bitmap on my 3DC model. Yes, I’ve managed to import a bitmap to use in 3DC “stencils” but of course that becomes a sculpting tool, not a painting one.

I realise that I’m trying to run before I can walk, but, in my mind, it seems that what I would like to do should probably be very simple. I have spent quite a time checking out various 3DC videos, but haven’t found the answer there, yet.

So …. 1 model in Rhino OK; 2 import sculpted model STL into 3DC OK; 3 add granite colour; 4 send to Shapeways for full-colour sandstone print.

Hoping some kind expert can offer some guidance in my quest.

Thanks

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This should help you. 3DC supports the exporting of VRML files (wrl)  Pretty sure 3DC exports version 2 of the VRML format.

https://www.shapeways.com/tutorials/exporting_to_vrml_and_x3d_for_color_printing . Shapeway supports bitmap textures that have a uv set, The creation of which is  very possible in 3DC.

https://www.shapeways.com/materials/full-color-sandstone

Some of the above you could have read already but here for your FYI. 

Also the above is not a tutorial on how to prepare the model for 3D color printing in 3DC.  I will look around for a tutorial for you, if I can not find one then if you like a skype session can be arranged.  A volunteer service I do at times when it would just take too much typing to explain. 

Side Note: The exporting for printing under the File menu will not work for full color printing as it only supports the exporting of Stl files and Shapeway requires VRML for full color printing. 

I am not a 3D printing expert as it is outside my workflow but the process I understand and how to get there in 3DC on the creation of the uv set and texture maps. The wall thickness and all such information is outside my knowledge at this time.

Edited by digman

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13 minutes ago, digman said:

This should help you. 3DC supports the exporting of VRML files (wrl) 

https://www.shapeways.com/tutorials/exporting_to_vrml_and_x3d_for_color_printing

https://www.shapeways.com/materials/full-color-sandstone

Some of the above you could have read already but here for your FYI.

Thanks for your reply, Digman. Yes, I've followed the Shapeways' instructions that you mention and, whilst I'm only using a simple 'per face' colouring method, I have uploaded a  manually painted file successfully. What I have failed to grasp though is putting a granite colour (bitmap?) actually onto the surface of my model in the first place, so that when Shapeways prints the full-colour model it actually looks like a piece of rock.

I haven't migrated to the "texture map" method of applying colour yet (mostly because it seems a little complex), but I had wondered if an alternative to applying my granite colour would be to export the 3DC texture map to a bitmap editor, add the granite bitmap to the texture map and bring it back into 3DC; I can't see that working though.

 

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You will need a uv set for the texture map method. Creating a uv set appears complex only because it is a new area that you have not learn yet. That happens to all of us when we are learning something new. Happens to me all the time but I know after awhile the light will turn on and it is no longer complex. 

It would be faster over Skype to help you but that is your call. PM me if interested.

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Thanks Digman. Yes, you're correct: I'd forgotten about the VRML. I will persevere for the moment, but I did welcome your comment about learning new routines. Frankly, I should probably fill in some of the gaping holes in my 3D learning, but I have a tendency to jump to the bits I need RIGHT NOW!

I'm not entirely computer illiterate, but once I've discovered how to PM you - I will let you know if I've advanced at all!

Your time is valuable, and I really do appreciate your spending some of it with me.

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Hey Phil,

Rather than starting a whole new thread I would like to add to this as well.  I work in the medical field and we are exporting our renders as stl through TeraRecon (TeraRecon FDA approved for creating DICOM renders).  Like you, I would  like to import these high poly stls into 3D coat to add texture and bumps in order to produce more realistic looking models.  We have access to ta Connex 250 (3 color) and  a J750 (multi-color)  

I've played with adding textures to some of our imported models and then exporting as an obj.  I then load it up into Netfabb to check if the texture held.  It seems that the texture is holding but bumps that were created do not hold, which in honesty is probably because i'm doing wrong ( i'm just using a brush and changing depth, don't know if that's the right method).  In any case, I would appreciate if anyone can help me with a workflow or provide me with documentation that will help given my needs.  In the meantime I will take a look at links that digman has attached to the board.  

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Hello eN0a,

Digman may give you some more succinct answers, but I can tell you how far I've progressed with this topic. Originally, I imported into 3DC a basic 'slab' made in Rhino with exactly the correct dimensions. No lumps and bumps ... which is what I needed.

Sculpting the lumps and bumps in 3DC to look like a piece of old granite was a bit time-consuming, but straightforward. After this, I thought to simply paint (texture) it as I wanted. Looked great, but couldn't export the .obj model with textures for Shapeways' printing. So, back to the drawing board several times in the last month or two. 

Retopologising is the key. See Alienminefield's YouTube videos at 

which are most helpful, although I must say that I nearly went crackers trying to retopologise my piece of granite. Following retopo, you can take the model into the paint room and paint it with colours, different brushes and even stencils. Then you can export the painted model (yes, VRML2 as required by Shapeways) and then upload the several zipped files.

I can't speak for any other type of printing, but I know that Shapeways explicitly mentions 'no procedural colour', which I take to mean PBR or 3DC's 'Smart colors'.

Like you, I have been concerned about the loss of  detail - especially after retopo: there seems to be a trade-off between original fine quality lumps and bumps and the retopologised model needed for painting/texturing. I've now ordered my full-colour sandstone model from Shapeways (I don't own any sort of printer) and I'll post a couple of photos of it when it arrives. 

I hope that this helps a little, but I admit to a lack of experience! 

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Please correct me if i'm wrong, it seems like retopo is a way to maintain quality by lowering your poly count whereas decimation will also lower poly count but lower the quality of detail, in some instance even deform the object if you are overly aggressive?  Either way to retopo the models i'm working with would take forever and I don't necessarily know if it's necessary as the printers we have can handle the large files and high poly count.  Nevertheless, my experience is limited so any knowledge for my specific use is greatly appreciated.  I attached a picture of one of the models we worked on.  I would love to add different textures to the heart, ribs and lung and be able for those textures to hold for printing on our Stratasys J750.

 

Capture.PNG

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Superb work. I see the problem with retopo!

I'm at the limit of my knowledge, I'm afraid. As I tend to  get confused over phraseology, are we talking 'texture' as in lumps and bumps? or 'texture' as in colour?

If it's colour, then in the paint room; if lumps and bumps, you could use stencils in the sculpt room, perhaps needing 'res+' at the bottom of the toolset.

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@Phil5635

FYI--- PBR Smart Materials are not Procedural. They can be used for vertex painting (poly painting) but only the color is supported in the exported file which is the limitation of vertex color format

The below is not a tutorial but the method.

Your workflow is texture map based for printing at Shapeways up to 1 million polygons. 

One workflow is decimate your model to just under 1 million polygons. Export that model and then import directly into the paint room using Automap creation for your uv set. It does not have to be pretty just functional.

Use  a smart material to create the look you are going for or hand paint. Now I do not believe Shapeways supports PBR printing.  The way around that is to bake the PBR textures and lighting into one texture map. Also the normal map depth will be simulated in the bake, not real depth but the appearance of depth. Most of your real details will be from the model itself but a normal map could be use to create small details which are baked into the texture map in blender. 

Blender is used to bake the lighting, PBR look and normal map depth to one texture file that Shapeways can print.

Example is the the skull and spline plus some ribs. Decimated to about 850,000 polygons. Imported directly into the paint room. Used a copper smart material. Next I would take this model into blender and bake the Lighting and PBR look into one texture map for shapeways printing.

The model is only for demo to show the process. This is in 3DC's paint room with a uv set and texture map.

Side note. Of course if you choose the blender route does not have to be used.. If you want to see what the truer appearance of your colors that will be printed switch to flat shade under the View menu. 

The scene lighting will have not effect in flat shade.

copper.PNG

Edited by digman

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@En0a

If your printers support vertex color printing. In 3DC you can vertex color paint (polypaint) the sculpt room surface mode models. The vertex color will be exported in the file. several file formats support vertex color. I do not know the file format that your printers support.

Model in first picture is vertex color painted. 

The other workflow would be the same as one I gave Phil minus the Blender part as you want just to paint some color variations.

I do not know how large in polygon count your models are. PPP mode can handle beyond 1 million polygons I have found. I have imported for per pixel painting up to 4 million polygon models.

Model shown just for demo to show the process.

Second picture is the model texture mapped with a uv set. The model was directly imported into the paint room (Per Pixel Painting ) using Automap for the uv set creation.

Side note. I had used Mesh Mixer and 3DC to clean up the scan some but not done for quality here again just to show.

Scan is from Embodi3D for non-commerical use.

wip.PNG

texturemapped.PNG

Edited by digman

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