Painting AM models in Zbrush

[JohnArtbox]

ZBrush 2 has arrived and AM has gone through so major alterations so I'm re documenting my AM to ZB and back pipeline. I've received a lot of queries about this so I thought I'd document it here. I'm going to check all of the asumptions I made when I originally mapped out the process a year and a half ago.

5 point patches are not particularly well handled in the obj exporter of the current version. I used to go back to version 8.5(which has a great obj exporter) but this afternoon I had an epiphany. By exporting to AVA and reimporting the model AM will maintain UV's while creating two 4 point patches wherever there are 5 point patches. You can then export the AVA based model without problems.

The image shows several different export options. The AVA is the only exported model which didn't created holes when subdivided(RHS image in each case).

[JohnArtbox]

I then did some very quick texturing and modelling in ZBrush. Using displacement painting I added breasts and stomache detail, plus some hair bumps, at the same time adding skin and hair textures. I then used the displacement map export to export the added detail as a displacement map. I placed the colour and displacement map back over the original model.

Once again 5 point patches were the main offender, causing creasing artifacts, but otherwise the process works well. If 5 point patches can be exported correctly and react cleanly to displacement a lot of models will be easier and less time consuming to create.

[KenH]

Good stuff! I wonder what the fine details look like from displacements. Will the mesh have to be subdivided(in Zbrush) more to get them? I'll have to look into it too.

[Rodney]

John,

 

Thanks for your research and documentation on this!

Another Thank you for the information on exporting to AVA to correct models... this could be quite useful to more than a few people!

 

Keep researchin'!

[jon]

could anyone compare increased geometry detail versus displacement maps as it impacts realtime 3d?

 

i imagine that with the newest video cards, displacement maps might be a more efficient way of adding detail, versus more complex geometry.

 

thanks,

-jon

 

ps: thanks for the legwork john!

[Zaryin]

Nice. I want to make a character where displacement would be a large factor, but am afraid to invest the time.

[binder3d]

How do you export AVAs?

[Rodney]

Christina,

 

From a Model window

Select Plugins

Export

Avatar 2 (*.AV2)

 

There may be other ways.

Here is a screenshot:

[nerrazzi]

Wait a second.... you can paint on A:M models in ZBrush? Is there a clone tool that will allow you to reference a pic and paint on the model using that reference? Like photoshop's clone tool...

[Michael Hartlef]

That's great. I own ZB2 too. But ZB2 can only import/export OBJ and DXF files. So how does it work when you export to AV2 from AM?

 

Michael

[Rodney]

As far as 'I' can tell, John is only using the AV2 (AVA) files to solve the problem of exporting A:M models with 5 point patches:

 

By exporting to AVA and reimporting the model AM will maintain UV's while creating two 4 point patches wherever there are 5 point patches. You can then export the AVA based model without problems.

 

Not sure of the final format John is importing into ZB2. But he is exporting the AVA out and then back into A:M to solve the model's mesh problems. *Most* exporters don't know how to handle 5 point patches. Evidently, neither does ZB2.

It sounds like John has found an excellent work around.

[Michael Hartlef]

ah, now I understand. He still exports with the OBJ plugin. Thanks

[JohnArtbox]

Quick answers

Nerrazzi: There's not a rubber stamp tool but you can do similar things, You could 3d copy by placing your model on top of an image or you can paint with a texture

There's a free demo which will let you experiment. If you want you can send me a model file and I'll convertin into a ztool so you can work with it in the demo.

(Note the demos 1.55, z2 is much better)

Michael>What Rodney said by converting the model file to get 4 point patches the exported obj file is much cleaner.

Zaryin>displacement works well if you can avoid using it on 5 point patches and hooks, and it can save a ton of modelling time.

More stuff later in the week, I'm going back to dinner now

[JohnArtbox]

Another zb painting test. I modelled the zpiral pattern onto the zb model and then generated a displacement map for use in AM. Because of the detail i added it in AM as a bump over the top of the previous displacement.

[John Keates]

Thats looking real nice there John. I must give this a go soon.

[KenH]

Aww Dagnabit....I saved the cage as an obj and exported the displacement map. Then in AM, I changed the map to displacement and this is the result. I swear I didn't model a dogs dinner!

Any ideas where I'm going wrong?

[Rodney]

John,

Looking VERY good!

 

Hmmm maybe we should warn the makers of ZB2 that the A:M users will be arriving shortly...

 

Don't forget to tell them John (and Animation Master) sent you...

[JohnArtbox]

Ken, I don't import Zbrush objects, I use it for painting my am built models.

If you're importing the zbrush models then I would assume that theimport function had problems creating continuous splines at join areas and that these then carried down the splines.

Here's my workflow

1.build in AM and assign a decal so that it covers the entire model(to setup UV's)

2.Export the model to an AVA file

3. Import the AVA file to create a new model (Steps 2&3 give you a cleaner obj export by getting rid of 5 point patches)

4.export an obj file.

5. Load the object into zbrush and asign the original object as a morph target

6. Paint textures and displacements (refer zbrush docs)

7 export the displacement and colour textures. (it may be better to export an obj because of some of the cleanup features, I'm still exploring this)

8. import the generated textures into you original AM model and adjust settings.

Questions welcome

[JohnArtbox]

Couple of questions Ken)I apologise if they're basic, I just want to cover bases):

did the model look correct before displacement?

Are all the normals facing the correct way?

Is the displacement map criented correctly(I do a flip vertical on impot and export)

[littleandy]

Hey John, I know this is probably a little off topic, but I really like that skycast lighting your company uses. I went to find it, but how much does it cost? I couldn't find that info anywhere.

 

-Andrew

[JohnArtbox]

http://skycast.artboxanimation.com

Cost is US$25.00

[Mega]

I highly reccommend it! One of the best bargains at $25!

 

Tony

[JohnArtbox]

I was sent these questions, but thought that the answers were worth putting in this thread. That way it becomes a mini FAQ

I have been trying to get my AM models into zbrush and am having some problems.

 

1.  I am finding that hooks create a hole.  What is the best method of solving this?

 

2.  I am not finding that the texture map gets carried across.  I am using the obj exporter from the resource matrix.  Is this the most up-to-date one?

 

3.  If I try painting on an imported model then I find that the texture map dissapears when I drop from projection master.  This happens even if I load the model into Wings and then save it back again.

 

1. In the latest beta this seems to be much better. I have found that it's not good to have hooks into the texture seam patches ie the ones that are on the outside of the stamp. When I run some more tests I'll post the results.

 

2. The texture map doesn't get carried across, but the UV's are written into the obj file. Once you load the object file into ZBrush, load the texture, flip it vertically and then assign it to the object. it will sit perfectly in place.

the obj exporter I have is 96KB and dated 9 Jan 2004.

 

4.When you drop the object in projection master the texture map disappears because it and the model combine to become a pixol surface. You can then modify the 2.5D image quickly and with a wider range of tools than available with a 3D model. When you use Projection Master to pick the model back up it rebuilds the model and texture to encompass the changes you have made.

 

This is the latest image I have done using this technique from the Superhero thread. To get greater percieved surface resolution I'm currently using the zbrush model to generate a displacement effect, and then (using the difference between the AM displacement and ideal subpixel displacement) generating a bump map which adds the smaller displacements as bumps.

[JohnArtbox]

Found an interesting side effect to the displacement maps. If you toon render them with a toon bias of one you get an edge around each subdivision, giving a kind of sketchy look. Because the effect is based on 3d geometry it animates well with very little jitter.

[cartoonimator]

Let me ask, could a similar pipeline work just as well in ZBrush 1.55b?

That's the one I've got, and I don't have the money to upgrade. =/ Did you have a previous pipeline for that version?

[JohnArtbox]

if you've got the full version of ZB1.5 then you get a free upgrade to ZB2.0. The pipeline for 1.5 is similar, the main addition is that ZB2 can generate displacement and bump maps.

If you are using the demo you're out of luck because it can't import obj files, it's one of the demo limitations

[zued]

HI.

 

.. I´m looking for a working link to the .obj -exporter.

Help needed..

 

Thanks

[KenH]

The object exporter is already in AM under Plugins>export>

[DMerchen]

Hey Ken, I am running the Beta, but I don't see the obj exporter. I see 3DS, ply, and AV2. Is there another exporter? Please...

[zued]

..same here..

[KenH]

Oh ok...I thought it was shipped as standard. It must preserve what's in your plugin folder already.

Put this into your HXT folder in the root folder of AM...

OBJ.hxt

[zued]

Thanks!

[KenH]

Just thought I'd share a rough model I got in from zbrush with displacements on it. This is all I got done before I was forced to stop due to some problems I was having. Hopefully they will be resolved soon though.

The displacements didn't actually come out too bad. There's another level of detail that's missing, but it's still ok.

I was going to woo a few zbrush forums with a cool Animation Master animation. Fingers crossed.....

zed.mov

[JackMcRip]

when you modeling in Z-Brush and export, will that generate triangle or quad Polygons ?

[KenH]

They're all quads and you can set it at different sub-division levels.

[JackMcRip]

WOW

 

Really Quads, no trinaglepolys.

I don't know many about, im/exporting.

I try something and all my Problems was when i want to import a model with triangle-polygons...

 

I'm very interested about Wireframes, that was modified by ZBrush.

 

I'm looking at the zBrush-Website and found this image:

 

There are triangle-Polygons!

Is it only because divide poly???

[KenH]

Anything made within Zbrush is made with quads. That image looks like the mesh has been optimised(reduced) and so tri-polys were created. You can see they are all in red. Either that or it was made in another app and imported in.

[JackMcRip]

Sounds very good !

There is no demo ZBrush 2.0 :-(

 

Is ZBrush realy a tool, that works fine with A:M ???

Or better use the fine UV-Editor ?

 

You have try to modify Models from A:M in ZBrush by zbrush-modeling-tools ?

[CRToonMike]

Thanks for the tute John!

 

I'll try it when ZBrush releases the Mac 2.0 version.

 

mike r.

[KenH]

You have try to modify Models from A:M in ZBrush by zbrush-modeling-tools ?

 

The main reason for using zbrush IMO is to generate bump/displacement/normal maps by painting directly onto your model. If you are worried about the model not animating well, just make the model in AM and import it to Zbrush and then get painting. But most of the time models made in zbrush will come through to AM perfectly workable with minimum tweaking. Just keep the poly count low and only use quads.

[Philip Fong]

Does the OBJ-exporter work on the current ver.10.5r?

[KenH]

I think so. I use v11. But importing with textures is a problem currently.

[heyvern]

Would zbrush allow you to import a "non-quad" mesh and save it out as a quad mesh?

 

Vernon "Ever seeking" Zehr

[KenH]

Yes. If I remember correctly, it allows you to set an option while importing whereby 2 tris side by side will be converted to one quad. Can't handle 5 points though.

[cartoonimator]

Thanks, John, I got my upgrade!

 

Now to play around a bit....

[JohnArtbox]

I've always avoided importing models into AM because I figured it was just as easy to model them in AM. Graeme the Barbarian is from an image I painted in zbrush last night, and while he's a lot more spline heavy than my usual the import isn't half bad. There's some splinage that needs to be converted with hooks and 5 point patches but he's a pretty good start for less than 40minutes of modelling time. Plus sketching him in threeD allowed me to resove a few problems before I hit them in AM.

This is a straight import, all I've added is a colour and bump material, and lighting.

[JohnArtbox]

And here's the original image.

[Rodney]

WOW. That is all.

[JohnArtbox]

Here's Graeme.

The LHS has the skintone map and zbrush's displacement map imported at the same time as the mesh. The displacement map doesn't work properly where the import has created a discontinuous mesh (noticebly on his face and at the end of his penis) but again I've been pleasantly surprised at the results.

One important factor was the use of the GroupUVTiles option within ZBrush. Using the AUV tiles option caused complications in the mapping. Apart from that and having to flip the textures vertically and resave them, it was a straightforward process. Rendertime was a pleasant 14 minutes on an Athlon 2100, with a twin SkyCast light and 25 passes.

From unpainted model through import and setup for render was about 40 minutes

[KenH]

Nice! He does indeed look spline heavy. I guess that is to get the displacement to work properly.