Exporting metaball as obj uv issues

Oso3D

So I made a random bunch of metaballs, converted to vertex, exported as obj, imported into Daz.

From what I can tell, uv mapping is pretty much... toast. No patterns appear, or it's some tiny corner magnified weirdly. So while I can certainly make cool shader stuff (like water and glass), anything using texture maps just doesn't work.

Any tips?

 

evilproducer

After you convert it to a vertex object in Carrara, can you do any UV stuff to it? I don't know the complexity of the shape, so it is hard to suggest a projection method. That, and I suck at UV mapping, so be warned, my suggestions may suck as well. ;-)

MarkIsSleepy

evilproducer said:

After you convert it to a vertex object in Carrara, can you do any UV stuff to it? I don't know the complexity of the shape, so it is hard to suggest a projection method. That, and I suck at UV mapping, so be warned, my suggestions may suck as well. ;-)

I think this would work,except the converted metaball is a real mess geometry-wise, so it's not easy.  I'm not great at UVs either but I gave it a quick try and there are no good edge loops to add seams and the shapes are weird enoughthat none of the default projections work at all. 

Here's my quick try - it's two positive metaballs, converted to the vertex modeler at 100% fidelity.  I added one seam looped more or less around the bottom to split it in two pieces and then unwrapped it.  I had to move the two islands around a little since Carrara just crunches them at the bottom of the grid, and the result was kind of distorted.  I added one level of smoothing before exporting (when you export from Carrara it converts those extra smoothing polys to real polys).  You can see it kind of works but still has quite a bit of distortion - if you really took your time with creating the UV unwrap I think you could avoid most of this, at least in parts you know will be seen in your render.

Image Below: UV Edit Mode in the Vertex Modeler, showing the geometry and my final UV map:

Image Below: 3DL render of the UV mapped metaball object, with a quick grid map applied, after I imported it to Daz Studio.  You can see it is pretty distorted in places because the triangles in the UV map above are all difference sizes - if I had taken more time on that I could have reduced the distortion by a lot.

MarkIsSleepy

I tried taking the Carrara export into Blender and using the Smart Project UV unwrapping then importing that one into DAZ Studio.  The results were a less distorted but there are still some issues.  I think to get a good unwrap on a metaball object you'd either need to be much better at UV mapping than I am; have a ton of time/patience; use a dedicated UV mapping program (I don't have one but from what I hear they have a lot more options for this kind of thing); or else after you create it, take it into a program like Blender and re topologize it.  I don't have any tips on that last one as I'm just starting to dip my toe in that subject.

To the OP's original question - any of the methods I tried will work if you want to 3D paint your texture on it, but I think that if you are just applying a premade image as your texture, then you are going to get some level of texture distortion unless you spend a fair amount of time on creating the UV's.  If you are going to use a texture that doesn't have a ton of detail on it, I'd probably go with the export to Blender and then use Smart Projection to unwrap it.

Image below: metaball object after being converted to a vertex object, exported from Carrara, imported to Blender, smart projection unwrapped, exported again, imported to DAZ Studio and rendered in 3DL with a basic checked pattern in the diffuse.  It sounds like a lot, but it took me a total of about 5 minutes to actually do it, and part of that was because my cat was attacking my mouse while I was working.

So if your texture image doesn't have a ton of detail and you're OK with the mediocre results I got above, you could try two things:

Method 1

1. In Carrara, Edit/Convert to other modeller (convert to vertex modeler/facets)
2. In Carrara vertex modeler, go to the UV Editing Mode
3. On the Unfold Tab select a line of edges splitting it more or less in half and mark them as seams, then unfold it (the more complex your metaball object was and the higher fidelity you convert it at, the harder this step gets)
4. Move and scale the two parts to take up more of the map (this is more art than science and is the hardest thing about unwrapping in Carrara because there is a lot of potential to add distortion to the map here, when you are supposed to be fixing it and Carrara's tools for moving the UV islands around are finicky and take some practice)
5. Select the whole thing and make sure it is at 0,0,0
6. Go back to the Assembly room, make sure it is at 0,0,0 here and move the Hot Point to the object, and export as OBJ with the default settings
7. Import into DAZ Studio with the default settings and set up your materials

Method 2

1. In Carrara, Edit/Convert to other modeller (convert to vertex modeler/facets)
2. Make sure the object is at 0,0,0 in both the vertex modeler and the assembly room and move the Hot Point to the object
3. Export to OBJ with the default settings
4. Import into Blender
5. Select the imported OBJ and tab to Edit Mode
6. Select the whole object and hit U for unwrap, then choose Smart Projection
7. Tab back to object mode
8. Export your OBJ with the default settings
9. Import into DAZ studio with the default settings and set up your materials 

Oso3D

Hmm, interesting, thanks a lot.

I'm still struggling with even the basics of UV mapping. The workflow you mention with smart projection looks useful. Is it pretty straightforward to do the projection unwrapped thing in Blender?

 

MarkIsSleepy

timmins.william said:

Hmm, interesting, thanks a lot.

I'm still struggling with even the basics of UV mapping. The workflow you mention with smart projection looks useful. Is it pretty straightforward to do the projection unwrapped thing in Blender?

 

Yes - it's literally just click a few buttons.

1. In Blender, File->Import->Wavefront (.obj) (it will probably import huge, taking up most of your scene, that's OK, just scroll your mouse wheel to zoom out until you can see it)
2. Right click on the imported object to select it (unless you changed your Blender settings and have left-click set as the selection key)
3. Tab to go to edit mode
4. Make sure the whole object is selected (it will be orange), if it's not hit A a couple times until it is
5. Hit U to bring up to UV unwrapping menu
6. Select Smart UV Projection (I used the defaults in the pop-up that comes next because I don't know what the settings all do)
7. Tab back to edit mode
8. File->Export->Wavefront (.obj)

One caution on the export though - make sure there is nothing else in the scene or it will all get exported together - the first time I tried it I ended up with an OBJ that included the ground plane I had added and the light I had in the scene. 

Oso3D

MD: I suspect a lot of people make that mistake. I've grabbed a bunch of free obj online and a bunch of them end up with weird ground or back planes that don't seem to serve a purpose. Thanks.