CAD & FBX imports - Retopo options?

Hello,

I’m wondering if anybody has had experience with importing high density, converted solids (*converted from b-spline to mesh) into Blender? And if so, how do you retopologize/remesh it? I’m using those terms interchangeably, so I’m not sure what the distinction, if any, is.

Depending on the model, these CAD files are usually high density, triangulated meshes. I know Blender has some good tools for remeshing, but it seems like they’re more geared for organic objects, and not hard surface. Is this assumption correct? I’m sure one could remesh a hard surface with such tools. I just wasn’t sure if there was a better way. Now, I have used the program MOI to covert to quads, at the very least. But it’s still extremely dense. I’d prefer to just handle everything in Blender.

Here’s a portion of the model I’m attempting, a Transformer leg (or GoBot if you prefer :slight_smile: ). If you want to take a crack at it, go ahead.

Transformers - Detour - Filleted Assembly.fbx (675.6 KB)

EDIT - I guess I’m looking for suggestions besides building another model using the snap-to-surface or shrinkwrap feature, and using the original as a guide.

what is your goal with this ?

it does not look bad in viewport

topo is not good but it looks ok to me

you could redo it in blender
no retopo
just model it
is not that complicated

happy bl

@RickyBlender Hi there -

Maybe for you :wink: :slight_smile:

The goal is to texture map it, so it’s going to be a tricky UV process. The end result will be for a “photo shoot”, or beauty render.

In short, I’m trying to acclimate to a commercial photography studio’s workflow. I’m aware it’s probably easier to use procedurals on this, but let’s assume there is a specific texture map that’s needed for the end product.

So I’m trying to balance accuracy and efficiency. I’m assuming the client wants an accurate model from the CAD assembly, then have specified textures in addition. This model is just an exercise, but these scenarios are what I’ll be faced with. I suppose down the road I’ll be quick enough to remodel something like this. The other difficult aspect of this is the watertight nature of it. I’ve heard of this Boxcutter add-on that would probably help.

watertight !
do you need to print this in 3D ?

did you try to assign several material to different parts of it and unwrap it to add images
as long as the topo/smoothness is there it should be possible to add some image texture and get a good rendre

or you could try to use some procedural texture

did you start adding some texture for testing it ?

happy cl

Hello,
Often you will get an assembly with more then 100 parts. So an automated remesh would be great.
Also the parts HAVE to Look exact.

Greetings

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“Instant meshes” might be useful.

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@polyboy

Absolutely. Exactness is the key here. I did actually buy a remesher from Blendermarket. Unfortunately, the results were horrible. But perhaps I just need to tinker with the settings more (even though I don’t think it will produce anything better).

That’s why I’m thinking auto remeshing just isn’t a good option for hard surface models. I’m having to take @Rickyblender’s advice and just remodel it. The results so far are OK. The trickiest part is maintaining consistent bevels, and incorporating holding edges (much of the bigger spaces converge into much smaller detail).

Also, Rickyblender, I did attempt to texture it. But even before that, if you apply a chrome matcap, you’ll see a lot of distortion. This is because of all the poling, tris, and stretched geometry.

Hmm- Can you get a STP file of the original CAD file and run it through moi3d? While not perfect, its mesher is much more UV friendly. For product viz like this our team here relies mostly on procedural texture. You may want to use Decal Machine for surface graphics or shrinkwrap simple subdivided 2D graphics planes to your model.
Not a big fan of retopo on large assemblies.

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Hardops also has some nice mesh clean up tools- combine that with manual edge loop cleanup and you can create a fast workable render mesh.

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@parel - Hello!

I have actually done that with MOI. And it does usually produce UV friendly geo - but in this instance, there is still a lot of manual cleanup involved. I actually use Fusion 360 for conversions. Still not great though.

Yes, Decal and Hardops, I was considering getting those! I’ll have to look into them a little deeper. I didn’t know Hardops had clean-up tools?! Is there a manual for that?

when you look at the model I’v shown in post 2 I think

it looks fine to me - very smooth and ok

what is wrong with it ?

by the way if needed there is another Retopo addon being worked on which seems to work very well and can lower verts counts with decimate I think
did you test it have to find the name but it is in the Addon forum

can you use procedurals textures instead of UV mapping?
UV mapping would give a more photo realist if absolutely necessary but require more work and this takes time to adjust !

happy cl

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if you use the moi export options with quads and n-gons- it seems friendlier for mesh post operations.
Upload your moi file and we can help further.
Hardops is somewhat brute force- Its a command to clean mesh. Helps in many situations but more suitable for planar surfaces.

@parel - Would if I could. The trial license expired a while ago, and since then I had to reformat my computer and lost my files. Haven’t been able to purchase a pro license yet. When I’m able to get around to it, I’ll let you know. But thank you for your suggestions and help so far!

@RickyBlender - Your screenshot looks fine. A matte texture would be ok. But I’m looking to add glossy, which is where everything falls apart. And you’re right, procedural might be the way to go. My goal was to simulate painted metal, and have stickers on the surface (like the ones that come with toys). But I might just add those as separate objects.

there are very good proc texture for cycles
including some with scratches ect…
and easy to add some glossy using principle shader
many nodes available

and easier to add labels as external object
may have to do some nice projection onto your model but should look nicely
may be remove the Lamps shadow and it will work well

happy bl

one problem I see now
model is like 10 mm
I think you gone have to scale up this to get a nice render

I did some renders here but model is too small

if you look at the bottom part with lots of details
at this size it might give some render problem cause it is too small
just in mm
which is at the limit of blender !
and the surface there is not flat it is a curve surface
also this does not have a lot of verts to define finely the surface
and may give some shading issues but would be difficult to correct

but it looks like you can add a subdi modififer and looks a bit better
but verts goes up the roof !

happy cl

some of the verts are not at same level and create shading issues
this creates some non co planar faces and shading issues

but is it supposed to be at same level

happy bl

@RickyBlender - Yep. That particular raised part is supposed to be beveled all the way around, actually. This is the downside to using others’ models - you don’t know what problems you’ll encounter.

That’s why I decided to try and attempt to just build it, using the original as a guide.

to get high precision model might be difficult

could be easier to correct the model here and there
to get proper smooth shape

also as I said model is too small at 1 cm !

or when you export it is it possible to increase number of verts ?
might help

happy bl

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Possibly, yes. It’s a balancing act though. I also have to consider the rest of the assembly (which are also complex). This is only 1 part of many. :open_mouth:

***there are some shortcuts I can take, certainly. In the end, I would like to render both car AND robot forms.

Screenshot 1 - top
Screenshot 2 - underside (lots of detail!)

do some testing to get some more verts on curve surfaces and get a smoother
surface
and see how it renders in blender

happy bl