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Pastscapian 09-20-2006 05:08 AM

Model sizes
 
Hi all,

We are creating a model for a third party who will he using Vizard to create a virtual tour. We are modeling in Cinema4D and will be converting to .OBJ for import into Vizard. We have a few questions regarding this that we can't find answers to:

Is OBJ the best format?
Is there a rocommended polygon maximum size for the total model?
Is it best to keep texture all at the same size: 512 for example?

We won't be involved in the Vizard side of thing, directly, but want to make sure we supply a model that's going to import and work fine, without too many changes to be made. It is a detailed model, and this worries me a little.

Thanks for your help.

Pastscapian

farshizzo 09-20-2006 09:18 AM

Hi,

1) The best format to export to would be Vizards native OSG format. There are OSG exporters for 3dsMax and Blender. OBJ should work for simple models though.

2) The max polygon count depends on the computer/graphics card being used. If you need real-time rates then it would be best to keep the polygon count under 200,000

3) The textures don't need to be the same size, but you need to make sure that the texture dimensions are a power of two. Also, most graphics cards have a maximum texture size of 4096, so an individual texture cannot exceed this. Again, the total recommended size of all the textures depends on the graphics card. We were recently able to fit a 50000 x 6000 size texture on a graphics card with 256 MB by splitting up the textures into 2048 x 2048 size tiles. So you can definitely put a lot of texture on modern cards.

Pastscapian 09-20-2006 09:36 AM

Thanks very much for that farshizo. There are several problems here:

1. Our model is far from simple.
2. It well exceeds 200,000 polygons (unless you mean 200,000 polygons in view at a time).
3. You can't export from C4D in OSG format, unless you know of a plugin that we're unaware of?

Many thanks,

Pastscapian

farshizzo 09-20-2006 09:47 AM

Quote:

1. Our model is far from simple.
By simple, I mean that the model is just a static set of polygons with a texture applied. The OBJ format won't support animations, shaders, or multitexturing.

Quote:

2. It well exceeds 200,000 polygons (unless you mean 200,000 polygons in view at a time).
Vizard performs frustum culling, so it will only render what is onscreen. However, to take advantage of this you need to ensure that your model is broken up into spacial hierarchies so that Vizard can quickly determine which part of the model to render.

Quote:

3. You can't export from C4D in OSG format, unless you know of a plugin that we're unaware of?
I am unaware of an OSG exporter for C4D. What formats does C4D support?

Pastscapian 09-20-2006 11:12 AM

Thanks for all that.

Cinema 4D will export 3DS, OBJ ect, but there's no OSG export, or a plugin that will do it. Would it be best to export as OBJ or go via 3dsMax (3DS) and export to Vizard from there?

P

Pastscapian 09-20-2006 11:28 AM

I meant to ask if the spacial hierarchies means that you can have a bunch of models, which may be 100,000 polygons or more and as long as they're all not being seen at once this is fine. Does this also mean that it can be used for going from a building exterior to it's interior which is a different model?

P

farshizzo 09-20-2006 11:29 AM

I recommend using whichever modeller you are more productive with. If you prefer C4D and the exported OBJ/3DS files work with Vizard, then stick with that. If you decide to switch over to 3dsMax, then we can provide you with better support, since this is the modeller we use internally at our company.

Pastscapian 09-20-2006 11:35 AM

We have to stick with C4D for the modelling, it was more a question of whether it's better to do the final prep and export via 3dsMax?

I think you were answering my previous post whilst I was writing another, listed before your last post.

P

farshizzo 09-20-2006 03:24 PM

Quote:

Originally Posted by Pastscapian
I meant to ask if the spacial hierarchies means that you can have a bunch of models, which may be 100,000 polygons or more and as long as they're all not being seen at once this is fine.

Yes, that is what I meant.
Quote:

Does this also mean that it can be used for going from a building exterior to it's interior which is a different model?
I'm not exactly sure what you mean here. Vizard does not perform occlusion culling, which means if you are inside a building it will still draw whatever is on the other side of the wall. However, you can manually switch off the interior geometry when you are outside the building and vice versa.

Pastscapian 09-20-2006 09:38 PM

Thanks again.

Will get back to you with more details to the other question as I have to dash of to the airport. Thanks again.

P

MuseumTech 09-27-2006 10:19 AM

Hi - joining here with a couple of questions farshizzo - we will be using Pastscapian's model in Vizard - exported through 3DsMax - thanks for the help so far. We have just purchased Vizard and are still getting up to speed - could you clarify a couple of points for me please. Why do we need spatial hierarchies if Vizard only renders what is on screen. Is there a speed advantage for Vizard in working out which part of a smaller model is in view? In some scenes there could be over 200,000 polygons in view at once in the model as it is. Will a better graphics card help here or does everything start grinding to a halt above 200,000. Can Vizard move seamlessly between hierarchies/models? Does it render all parts of every model in view - ie if you are in one model but can see through a doorway to another. Thanks

farshizzo 09-27-2006 01:03 PM

Quote:

Why do we need spatial hierarchies if Vizard only renders what is on screen.
Vizard will not split up meshes and only render the parts that are in view. If even one polygon of a very large mesh is in view, then Vizard will render the entire mesh. So if you have a mesh that takes up a large area, then I suggest you break up the mesh into smaller pieces.

Quote:

In some scenes there could be over 200,000 polygons in view at once in the model as it is. Will a better graphics card help here or does everything start grinding to a halt above 200,000.
I just threw out that number as a general guideline. A better graphics card will definitely be able to handle more polygons.

Quote:

Can Vizard move seamlessly between hierarchies/models?
Sorry, I don't exactly understand your question here.

Quote:

Does it render all parts of every model in view - ie if you are in one model but can see through a doorway to another
No, if your model is split up into submeshes, then it will only render the submeshes that are in view. However, as I mentioned in an earlier post, Vizard does not perform occlusion culling, so it will still render objects that are occluded by a wall, for example.

Pastscapian 10-03-2006 08:12 AM

Thanks for all the answers Farshizzo and and glad to see that MuseumTech, our client, has joined in the discussion.

Whilst I've managed to greatly reduce the polygonal count of our C4D model it will be interesting to see what happens when we put it into Vizard tomorrow. This is going straight in via C4D's .3ds export. It's a shame that the format is so old and doesn't handle UV's too well (with textures ending up all over the place) as it would certainly have been the easiest way for us to export. As it is, it looks like we'll have to go via the .obj route to 3DSMax then in to Vizard. (Not such and easy method from C4D but with much better results). There is no OSG option, which is a shame. Would love it if someone would come up with a plugin for C4D and I can think of a number of people who'd like it too.

If you have any advice on any of this it will be gratefully received.

P

Pastscapian 10-03-2006 12:18 PM

Forgot to ask one more question: can Vizard import fbx files?

P

farshizzo 10-03-2006 12:33 PM

Vizard does not support fbx. We are currently experimenting with a new COLLADA importer. The COLLADA format is looking to be the next generation universal 3d file format. Most modelling programs already have some basic support for it. Does C4D have a COLLADA exporter?

Pastscapian 10-07-2006 02:48 PM

No, there's no COLLADA exporter for C4D. I just had a look at the COLLADA forum, where another C4D user posed the question and their answer was "... if enough poeple ask Maxon.." so I'll join in there, along with a request for an OSG plugin.

P


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