Sketchup, UVs and cleaning models for export

Kenny Bones

Ok, I love Sketchup and it's userfriendly interface. And it's real easy to model buildings.
But I'm having real trouble with exporting my models to external softwares like Zbrush, Bodypaint etc.
First of all, I've tried different settings for export and how found that some basic settings keep my model intact, but Unfold3D says that there are errors in my mesh and UVs come out all scrambled and stuff. Also, trying to paint on the model in Bodypaint creates odd results. It seems as though my model has several "layers" of UV or something, cause when I try to paint on the model, I simultaneously paint on other places on the model too. I guess this has something to do with Unfold3D giving me the error message and stuff.

I created a thread about this is c3dcafe.com:
http://www.c4dcafe.com/ipb/index.php?showtopic=34981

Now, I don't know all there is to know about 3dmodels, in fact, I don't know much at all!
What about UVs, do they always matter? Do I NEED to set up UV correctly to be able to texture my model?
It's building by the way, very simple.

Also, what settings to you use when exporting Sketchup-models to other 3d apps? I've heard something about "reversed faces", but my model doesn't seem to have any. What is your best workflow when exporting models?
Do I need to setup materials? Do I need to do explode all components from my model or should I create a component of the entire model so that it becomes one component? What should I do?! Thanx in advance.

Tobobo

Kenny,

I'm no expert at rendering but one thing I can see that might solve it is try to create the face on the lower wall as one face.

Kenny Bones

Sorry, I don't quite understand what you mean here. I'm not really trying to render anything, I'm just trying to wrap my head around this whole exporting thing, what format to use and which settings to use when exporting from Sketchup etc. Anyhow, I just created a window just now in Sketchup and exported this to OBJ and imported it into Bodypaint. Then I exported it to 3ds and imported it again and the whole model became one object. I think this might be the right approach. It certainly made the UVs alot better! At least I'm not painting on several layers of UV now.

This is the window in Sketchup

And here's what it looks like in BodyPaint 3d at the moment:

Still, there's something not quite right. But that may be just the use of Bodypaint I guess. I've painted the edge on the window with a white color. And on the UV-map it seems as though it's been separated into several individual squares (well, two triangles put together to form a square)

But in general, seems as though Sketchup relly sucks at exporting and that you can get various results everytime you try. But it seems as though Sketchup creates a new object everytime something is copied. For instance, I created a window and made this into a component. Then I copied that component and never though more about that. But now, I see that since all the copies of that window is identical, all texture I apply to one window gets transferred to the other windows as well. Surely there seems to be some sort of connection here.

Edit: Rightclick on the last image and press "view image" to see the entire image. Looks like these boards have some sort of max width set on pictures.

Kenny Bones

Wait a minute, just found out something. Ok, so I selected all windows on my model in Zbrush (the components) and clicked "explode" and then I removed all components while the windows were still intact on the model. And then I selected everything in my model and chose Intersect --> Intersect with model.
This took a while, but now when i imported this OBJ-file into BodyPaint, there's only one single object! Hooray! Could this actually mean that modeling in Skethcup doesn't need to be a pain later on? Certainly would seem that way. Now, I just need to figure out how to layout my UV-map to make it behave a bit like this:

See, the edges are somewhat connected together in order to have seamless textures. Oddly, my UV map seem to be not connected at all, where each little part and bit is assigned it's own separated space. Should be able to connect the ones I want, just don't know how yet. Or if there's a more automated way of doing it.

solo

I have never used the software you intend exporting to so my advice may be pointless, however you can try the following (back up your model first)

Try exploding your model and exporting.
I use Deep Exploration for all my file conversions, especcially to .3ds as it keeps the mesh intact and maps the UV's much better.
Make sure all your faces are correctly orientated before export as sometimes it creates problems in third party apps that only recognize single faces.
Choose the 'stand alone edge' option in the export options when using SU .3ds exporter (seems to keep model more stable)

These are only ideas as I have not experianced your concerns, hope they help.

Kenny Bones

Ok, just thought I'd edit this post.
I now understand how the UVs work and how I can arrange parts to make sure there are no UV overlapping, which is the main thing I need to focus on. Where each UV-part actually are would actually be quite irrelevant since I would be painting textures directly onto the model in Bodypaint or Zbrush. Therefore I don't need to worry about where the UV actually is. I just have to make sure it's projected properly and we're good to go! I think I've finally found a workflow that can actually work!
My back actually shivered a bit just thinking I possibly would need to learn how to model in another 3d app than Sketchup!:P

Will post results in this thread from now on

Kenny Bones

Ok, another question now. After talking to some experienced modelers who's taken a look at one of my Sketchup models of a window in Cinema 4D, they say that the model basically is a huge mess. Meaning, there are triangles everywhere and some ngons too. They recommended me to remodel it in Cinema. But I really don't want to do that! Sketchup is so easy to understand! Why can't the development team do some more work on the export-feature and make some good export-features instead= So that it won't be a big mess?

Chris Fullmer

One of the rason that SU is so easy is because it ignores some aspects of modeling. And it gets especially ugly when you export it to another 3d app. What they want to see are a bunch perfectly triangulated faces. But SU doesn't worry about each and every line that actually makes a face. It only cares about the edges of faces, which is why it is so easy. I don't think I'm explaning this very well. But essentially SU doesn't model the same way that other modelers do, and it tends to look VERY messy when imported in to those other modeling softwares.

Chris

Kenny Bones

Hmm, I see.. I get what you're saying. But then I don'¨t think I understand exactly how other 3d apps really work. Can't believe that the model get completely useless after exporting from Sketchup. The export features ARE there, so it must be possible to clean up the model after exporting somehow.
In Bodypaint, I tried to convert all geometry to ngons and all triangles was lost. But after working on the UVmap a while, I got this error that several faces was shared by a polygon. And a few other glitches in the model. But other than that, it works just fine.

Could it be possible to write a rubyscript that scans for these errors? And then fix them?

Chris Fullmer

I don't use other 3d apps too much, so if there is way to clean up SU models, that could be cool. But I think its a common problem where one program that works one way will always export a little bit less than perfect to another program. CAD to SU is another example. It works, but it takes some cleanup in CAD and SU.

There are definitely examples of people doing very high poly stuff in SU, then texturing it in SU (I think) and exporting it succesfully to a renderer and getting inredible results.

So I wouldn't call it completely useless. But I think it does get a little bit clunky, because of the way faces are turned into triangulated geometry.

But for sure there are people who know a lot more aboutt he technical details of this than I do....

Chris