Geometry breaking Cheetah3D 4.0 -> Unity?

Have any of you experienced geometry transfer problems from Cheetah3D to Unity? What might be the reason for the mesh exploding if there are no bones in the models?
The geometry is originally from 3DS MAX, but Cheetah3D shows it just fine and additions are made in Cheetah3D to the original model. The .jas was saved to Unity Pro project folder. See the result image attached.

 

After discussing this with Martin, it seems that the problem is Unity related as other 3D software (Maya, MAX, Cinema4D) load the scene via path Cheetah3D -> FBX -> 3D App just fine. Unity is the only one that explodes the meshes.

 

Thats one of those report bug type scenarios that means the brains round here gets to see your model and work out what caused it to go astray. It some times happens to me from bryce to unity or bryce>maya>Unity, if I make something with loads of intense angles and long n-gons. Try saving it to a few different formats though, that might fix it?
Good luck, it looks like a sweet model.
AC

 

I've occasionally had problems with models from Blender importing wrong if they are saved with quads. If I convert the quads to triangles, the problem goes away. No idea if that's the case here, but I'd thought I'd mention it.

--Eric

 

I never had any issues with static mesh export from C4D. If you like, i will give it a try, exporting the model from c4d to fbx. C4d can read .3ds files, so this wont be a problem, i think.

Edit:

Maybe there is a problem with n-gon export? Did you use any n-gons in the original model?

 

Try unchecking recalculate normals inside of the Unity import settings of the model.

-Jon

 

Thank you for your responses. Actually some of these misbehaving objects are from our client that wants us to prepare a visualization from a set of models that we got in FBX format. According to your suggestions I've tried so far:

- direct 3DS MAX orginated FXB import to Unity
- import FBX to Cheetah3D -> JAS -> Unity
- import FBX to Cheetah3D -> FXB -> Unity
- import FBX to Cheetah3D -> obj -> Unity
- import FBX to Maya -> .MB -> Unity
- turning off the automatic normal calculation in Unity import
- in Cheetah using triangulate and optimize (removes isolated vertices) tools for the model


There are no bones and shouldn't have ngons in the model (esp. after triangulate in Cheetah).

None of this helps. The worst thing is that we do have several of these models coming to us that we can't get into Unity in a proper way, while they seem to be ok in Cheetah3D, Maya and according to Martin at least in one test case in C4D also.

The whole scene is fairly large, but I can e-mail one exploding object (telescope) to Alpha-loop, thanks for the offer of having a look at this! See the images attached how the telescope model behaves in Cheetah and in Unity PRO in this post.

We'd like to be able to show something working to our client soon. I'll also send the telescope object via the bug report tool to the Unity guys, any help greatly appreciated!

- JR

 

Ok, maybe this will help.

If you have "impossible Quads" in your Model, the triangulation could mess up the model, like shown in this example...

Until triangulation your model may look fine inside the 3D app.

If your model contains some of these, try to triangulate the quads by hand, before giving the rest to the software. In some apps you can also flip the verts, that part the quad. Could be worth a try!

Cant think of another solution yet. And i am still willing to test one or part of your model from C4D converted to FBX to Unity, if you want that.

Cya

Frank

 

I posted the telescope scene with the reporting tool as Case 10466. Do you need some other form of posting? I also sent the FBX via e-mail to Alpha-Loop, even this part seems to be 4M zipped so it may get stuck somewhere in between.

Thanks,
- JR

 

4 Mbs are no problem. I will give it a try!

 

That looks like a Lot of polygons. are you sure it isn't a vertex count problem?

 

Hmm. Maybe in Maya, have the polycount HUD visible and select the model>merge verticies?-Maybe the model is built a bit funny? And yes, triangulating it in Maya is a good idea too.
Post the models here, if someone can get them working, we can send them to you in a unitypackage?
AC

 

Hope the forum does not get stuck with this... It is the original fbx that I received, zipped. Hmm, regarding the polygon count: if there are too many polygons, would it still load? I've experienced polygon count complaints in Unit with other models from the clients, but then the whole model didn't appear at all when dragged to the scene.

If this is related to the polygon count, it is a bit problematic as in product model visualization the models can be originally from CAD. Those programs tend to triangulate their parametric surfaces to a huge soup of triangles. Naturally there is no sense in displaying 1000 000 tri coffee cup, but it might be fairly difficult to reduce the triangle count to 1000 for example without the model breaking up in the reduction tool already. As far as I understand some reduction has already being done for the telescope (I do not know if this was originally a CAD model), but this model can tolerate more reduction I think.

It is very interesting to us to see how this turns out as I'm afraid we can sometimes get quite big models from clients. However I have to say that I got approx 400 000 tri machine model yesterday from a client's SolidWorks CAD program and it displayed in Unity just fine after getting it to FBX! The reason for this was that no single part had more than 40k tris.

I have to check the Maya hints as well mentioned here.

Thanks again for assistance!
-JR

 

Hmm... is this some kind of 3D Scan or was polygon reduction used on it?
There are many parts with very unclean geometry.

The dish for example will have shading issues in the areas marked 1 and 2. A round form should be modeled with polys of equal size, or as equal as you can make them. The geometry piercing through the dish at point 3 will also cause flickering or even worse effects.

The Triangulation is really messed up. To guarantee a clean shading and geometry rendering the triangulation should follow an equal pattern. This is not given in any way throughout the complete model. The tris are very long, normally two "good" tris should form something equal to a quad or rectangle.

Automatic optimization function of C4d removed more than 4.000 Polygons, that shared the same space, or of geometry with a thickness of 0. That will lead to display problems too.

There are normals flipped, wich will cause rendering issues.

I could continue the list on and on... in one word the model is a complete mess, in my opinion unusable and non-fixable at this state. I can tell only one thing for sure here... your problem is not unity or max related, it lies in the model itself.

Is there an untriangulated version i can look at? At best a model, that was not send through poly-reduction processes as well... Parts of the original Model will be enough to evaluate the original quality and to find a solution. 3DS Format is no problem.

 

Thanks for having look at the model. Sure it is not a nicely constructed model. However this is the stuff we got. And this is not the first time things are like this.

In the gaming world people can build models nicely for a specific purpose. In the product visualization world the situation can be a little tricky: we are sometimes forced to try to cope with models coming from CAD packages like CATIA, SolidWorks and others and there may not be enough resources to remodel the meshes from scratch. The meshes tend to be sometimes nearly very difficult to use for nice visualization.

However with this particular example: I still don't understand why Cheetah, C4D and other display it correctly (in its not so nice state) and Unity just explodes it?

- JR

 

Sorry I didn't answer to the question if I have non-triangulated model. The FBX is what I've got, but I'll try to ask for a model in its more original form!

- JR

 

I dont really know the exact reason, but a game engine is optimized for speed and realtime effects and therefore needs optimized input as well to do a good job. Living within boundaries is what GameDev is about... Thats for sure.
And just to mention, putting shaders on that model for high quality renderings would surely end up with light- and renderartefacts, when taking a closer look.

But i see your problem. And its not a small one if your client has no other files...
When you get other data than the posted .fbx, feel free to send them in anytime and i ll take a look.

Frank

 

I've been following this thread as we are also frequently called upon to work with models that originated in Solidworks or some other NURBS CAD system. Like yourself, the models we often get are in the hundreds of thousands of poly's in size. The problem is that no current game engine (that I know of at least) is designed to handle such large numbers of poly's (EDIT: And as Alpha Loup correctly explained, game engines also require specific mesh qualities in order to properly display a 3D model) and the CAD apps themselves usually don't do a very good job of optimizing their output. Even the 3D tools we normally use to produce our models (Cinema 4D, Carrara Pro, Modo and Blender) don't seem to handle such huge poly models very well. (Side note: Beleive it or not, Blender seems to handle high poly models the best of everything I've tried so far.)

The only reliable and economical solution we've found so far is to manually re-create the entire model to bring its poly count to a manageable level. Optimum poly counts for Unity are around 4,000 per object, and that's normally what we shoot for.

The other option is to use one of the mesh reduction applications available, but the only one that IMHO does a decent job of maintaining the mesh's geometry while bringing the polycount down to a usable size is way out of our price range (SIMS Rational Reducer http://www.sim.no/products/RR/app/ ).

Hope this helps.

 

I can second and recommend that. But looking at the complexity of the models it will sure take about 2 - 3 weeks per model time and a pro skilled vertex-pusher who knows what he is doing... when you aint got that at hand, its getting something between expensive and impossible.

But hopefully there will be cleaned up models available. C4D for example comes with a very easy to use poly-reduction tool. And as long as the original is made of clean quads and is then triangulated, it comes out with good and fast results. I will give it a try, when i get the new test model.

 

Yup, there in lies the dilemma. I've spent 2 weeks doing both: reducing, cleaning, and UV mapping a model or re-creating from scratch. Seems like a waste of time when you already have a model on the screen, albeit one you can't use in your game engine.

FYI, SIMS Rational Reducer sells for $8,000 USD, cough, cough, but does a lovely job of reducing a high poly mesh like this.

 

yeah, i'd imagine rebuilding to be the only controlled way to do it as well. especially if you're going to have anything other than a simple tiled texture - unwrapping that monster would be a PITA (and i can't imagine that's already done for you if they're cad models).

the one bright side though is IMO its much easier quicker to model something when you have a correctly proportioned 3d reference available ; )

 

Thanks a lot for your feedback and efforts in this area. This discussion has been most useful.

We have also tried different polygon reduction tools, it is interesting information to hear that you have figured out that Rational Reducer could probably be among the best. I've no personal experience on this tool.

I'm sorry I didn't notice the 65k limit for this particular model, as a new Unity user I encountered the limit a week or two ago but got the warning from some other models so I didn't suspect anything in this case.

Now we can proceed! We are actually intending to build something that involves interfacing the application with particular machine hardware. It might not be a spectacle in computer graphics terms, but it could be interesting for people to see how widely Unity is actually applicable beyond gaming. I will post something to the forums when we get there (there should be an exhibition in August where these things will be demoed).

- JR

 

My background is 3D military training apps.

I've worked on a lot of DOD projects and this is how you handle such projects.

1) Render textures from the High Polygon Models.
2) Model low polygon versions.
3) Map the the textures onto the low polygon versions.


FYI: The best poly conversion tool on the market is polytrans by www.okino.com - Polytrans was a GameDeveloper Front Line Awards winner and has been around for 19 years. Not sure how good the reducer tool is but rendering to a texture is the BEST polygon reducer period.


Cheers,

 

VICTOM - Good tip about Polytrans, haven't used it, but at $400 it's a bargain compared to the SIMS product (assuming it does a comparable job).

I have a question about the workflow though: The problem we normally run into with models from CAD apps is that the mesh is, in addition to having way too many polys, is a mess and would be very difficult to UV map. Does Polytrans have tools to automate UV mapping / texture baking in addition to mesh reduction? I've got a half dozen models from Pro-E I'm going to have to reduce in the near future. If Polytrans can automate the process it'll definitely end up on my "buy" list.

Thanks!

 

1) Don't UV the Hi-Poly models. Render them as orthographic textures.
2) Do color passes in PhotoShop, much faster and easier.
3) Take the orthographic renderings and map them on your (hand modeled) Lo-Poly versions.

---------------------------------------------
This is a supplied penciled character drawing.
http://tryster.com/pages/Stalker_Step1.html

This is the color passes in PhotoShop.
http://tryster.com/pages/Stalker_Step2.html
---------------------------------------------

Although the image is not an orthographic rendering from a Hi-Poly model it might as well have been. The color pass was completed in a day's time. Multiple DOD textures could be completed in the same time.


Another solution to "Fixing" bad model topography and reducing high polygon count is to use the topography bush in SILO. Not sure what the max poly count for SILO is but I think ZB3 (release date May 15th) will also have a topography brush and will be able to handle a mere ONE BILLION (yeah a billion) polys.

Truth is most of the DOD models in a project are just background models and don't need anything more than crude 3D shapes that have nice textures. Any models that need to be interacted with will need special modeling attention.

Unfortunately there is no "push button" solution to fix this issue. You will need production artists involved with this project. Let me know if you need any help with your pipeline. At least I hope this was informational and of help.


Cheers,

 

Yup, that's our situation. Ortho renders mapped to simple cubes or other simplified geometry won't work for us I'm afraid. I'm gonna give Polytrans a try to see how well it does in reducing the mesh, but past experience with mesh reduction apps usually caused a mess for UV mapping.

Your tool combo of Silo + Cheetah sounds like a winner. Haven't used Silo on a Mac yet, but loved it on a PC.

 

[Sorry JR I just realized this was your thread]

bigkahuna <- then you really must rebuild the geometry the way I described. I think you maybe over simplifying and discrediting this method I'm describing.

The LO-poly versions are not OVERLY crude - just what needs to be there for making an interactive model and nothing more.

I've worked on 3d manuals that dissembled tanks and trucks. Then had the user rebuild them, using these methods. These same models trained the user on the internal job/work areas of the vehicle.

Your not going to get that from running your DOD supplied assets though any poly reducer.