3dsMax/Zbrush + GoZ and Scaling issues while setting up for rigging

[Kidd_Kosmonaut]

Im running up against an issue when using the GoZ feature of Zbrush to link into 3dsMax. I created a model in Zbrush that I want to rig in Max. I got about 95% of the modeling/texturing done in Zbrush and then GoZ'd it into Max. When the model came into Max it was super small so I had to scale it up for the rigging procedure. About halfway into the rigging I wanted to make some very small topology changes (add some ring loops, even out spans, that sorta thing). Typically after I make a topology change in Max I will GoZ into ZBrush to smooth out spans or make sculpting edits or to reproject textures that might have gotten messed up with the topology change. Now that I have made the scaling change to my model for rigging when I GoZ it into ZBrush the sculpt model is no longer the same size as the rig model. The rig model comes in WAY bigger then the sculpt model. The rig models' scale is proportionate to the home grid when in perpective camera in max so it appears to me to be an appropriate size for the model/rig (which is to say im not doing some insane or extreme scaling on the model). However when the mesh comes in at this larger size it makes certain brushes in ZBrush not perform the way they should. Im just wondering if other people have had to deal with this and what a workaround might be.

[Kidd_Kosmonaut]

So I had some success this afternoon although it still leaves a little to be desired. So I made some topology changes to my character mesh and wanted to Symmetry those over to the other side. I did this and then my UV's werent symmetrical (both halves were sitting on top of each other). I brought the mesh I made changes to in Max back into ZBrush. Once again, the max mesh was huge compared to the ZBrush mesh. With the Max mesh selected I could use the Unify option under deformation to make it the same scale as the ZBrush mesh. That was great because I really don't like having to eyeball match scales' between meshes, its a pain and usually somehow introduces problems. So then I could do all my projections no problem because the meshes were right on top of each other. With that completed I was ready to go back into Max. Back in Max my GoZ import from ZBrush was tiny again compared to my Max rig mesh. Here i was hoping to mimic that Unify scale match that I did in ZBrush, that made my life so easy , but was unsuccessful. I tried aligning the position and scale of the ZBrush mesh to the Max one and tried all the various options (pivot point, center, minimum, maximum) but none of them matched my zbrush mesh perfectly with my Max mesh. Tried to do a bunch of things but none of them quite got me where I needed to be. In the end I was able to copy a UVW modifier off of the ZBrush mesh, eye dropper the material off that mesh too, and then apply those both to my rig mesh. So this works for getting textures from a ZBrush mesh onto a Max mesh in the case where the ZBrush mesh was imported into Max and there are scale discrepancies. However, if there were sculpting edits that I needed to get onto my rig mesh I would still be having a problem. I did try placing a Morpher on my zbrush mesh and setting the target to the rig mesh but it didn't work how I thought it would, the mesh just moved globally slightly (which I think is suggestive of a pivot offset between the two meshes) but it didn't scale up to the size of the rig mesh or anything.

Ideally any edits made in ZBrush would be imported into max and I would be able to get the newly imported ZBrush mesh to REPLACE the one that I am using currently to template out my rigging (I haven't skinned to it yet or anything just getting placement down for all the rigging). That way I don't have to worry about transferring maps, sculpt edits, whatever from one model to another I could just use the new model with the most current textures and modelling. Zbrush seems to throw a monkey wrench onto what could be a beautiful harmony by scaling the model during the GoZ process. GaH! why do they do this? Anyway, for the moment I have a way to transfer textures but if anyone has a way to transfer sculpt edits, or better yet, a work around for the GoZ-scale-monkey-wrench issue.

*Brainfart: Maybe I could create a Morph Target when I first import the mesh into ZBrush capturing at the scale that is needed for the rig, then Unify the import down to the size of my ZBrush mesh, make any modelling/texture changes, when finished morph back to Max size and then GoZ into Max.

[Anonymous]

All you have to do is make a tall box in max, make the box 200cm high and import that box into zbrush. In zbrush unify the box and go to the export settings at the bottom of the tool menu. GoZ the box into the max scene with your 2meter high model and play with your export settings until the GoZ box is exactly the same as the box already in max. Takes about 1 minute.

[Kidd_Kosmonaut]

Hey so I'm pretty sure I am following what you are saying but Im not getting very successful results. First off, when I try doing it with a cube I will create the cube in Max, GoZ the cube into ZBrush, Unify it, and then attempt to GoZ back into Max. When I do that the cube coming in from ZBrush just replaces the cube that was in my Max scene and I am unable to compare the results without having both pieces of geometry in the scene. I was assuming the cube coming from ZBrush would be added to the scene (not replace current geometry in the scene) and in that case, yeah I could just keep GoZ'ing cubes out of ZBrush until I landed on the proper export settings out of ZBrush.

When I attempt to do it with my character model I get slightly better results, that is the incoming model from ZBrush is added to the Max scene and I can visually see scale comparisons that way and can fiddle with ZBrush export settings until I get something close enough. However, I am trying to make morph targets out of ZBrush and I need the mesh from ZBrush to be exactly the same size as the one in Max not just close enough. And so far, even after many attempts at changing the scale in ZBrush export settings I havent felt confident that the ZBrush meshes are the exact same size. It further complicates the matter that there is some sort of offset between the incoming ZBrush meshes and where my model sits in the Max scene. So it becomes this process of moving the ZBrush mesh around slightly until it lines up with the Max mesh and then I have to eyeball it to see if it looks like its the right scale which is not a very exacting method.

In the meantime I guess I can just export OBJ's from Max>ZBrush>Max because when I do that I don't have to worry about all this stuff. However it would be really nice to take advantage of the GoZ feature if it wasn't causing these sort of problems. Any further instruction on the issue is appreciated.

[Anonymous · Accepted solution]

Yup I see what is going on.

Make a cube in max like I said and make it at x=0 y=0 z=0 and copy it. Send the copy to zbrush. In zbrush unify the mesh so it is at optimal zbrush size for all the edit functions in that application. CoZ the imported copy cube out of zBrush and play with the export settings until the cube you export is exactly the right size and position as the cube in max. You will find that the settings in zbrush are numbers like 1 and 9 and so on which means you dont have to fiddle very much to get it exact. We are not interested in the cube in zbrush just its export settings and size in zb. Import your character into the scene in zbrush and scale the character so it is exactly the size of the cube subtool. GoZ the character out of zb to max and use that mesh to as a base for your morphs. Saving the ztool using the save as or saving the project will save the export settings for that model. Using this method you can even make stuff in max and bring it into zbrush and everything will be the perfect size, always.

Hope this helps.

Cheers

[Kidd_Kosmonaut]

Ok cool. Im getting something closer to what you are describing now.

So my MAX mesh was rigged and skinned but it seems like it will be easier to just reskin a mesh that I generate via this process out of ZBrush that way I know my verts are all lining up except for the ones I have edited for morph target purposes. I would have tested a morph on my skinned mesh to make sure but during the GoZ process out of ZBrush my new mesh generated a few extra verts somehow so I cannot really test how it would have effected my skinned mesh. However all my subsequent GoZ'ing is landing these meshes right on top of each other with identical vert counts which is perfect.

As an aside, I was following Digital Tutors Creating Morph Targets for Facial Animation in 3ds Max and ZBrush and the instructor makes absolutely no mention of this issue when jumping from Max to ZBrush. Which caused me to think 'Is this a common occurence or does it just happen occasionally?' It seems to me based on my last year of trying to create a character production workflow between Max and ZBrush that this occurence happens every time. Which again forces me to ask why there was no mention of it in the Digital Tutors tutorial? Not expecting an answer to this by any means it has just been a point of frustration of mine when tut providors gloss over an important aspect of a procedure.

Anyway, thanks a lot for your help!

[Anonymous]

Ok what I forgot to mention is that I make my first cube in 3dsmax 2 meters high for a full body character, that way when the character goes between zb and max it is optimized for working in zbrush and is a real world size for max which has all sorts of advantages further down the line.

I dont know why people dont have a problem with this. The first thing I did with GoZ was export a zsphere generated mesh out of zb only to find in max that it was tiny. I like to go between zb and max a lot and often have them both open. I think perhaps many modellers do everything in zb and only export the end result and rescale the result then. Also if the instructor has done this a thousand times before then it is easy to forget.

Glad I could help.

Cheerio

[Anonymous]

That technique is not exact. In order to get your meshes exact do the following:

1. In 3DSMAX you can use GoZ or just export your model as a OBJ.

2. Load your obj into Zbrush or if you used GoZ from 3DSMAX it will already be a tool in ZBRUSH

3. In ZBRUSH draw out your tool or mesh if you will onto the screen and hit EDIT. Then go to Deformation roll out in ZBRUSH.

(DO NOT HIT UNIFY as stated in other posts) You can hit UNIFY but your scale back to 3DSMAX will be wrong!!!

4. Instead of UNIFY I want you to use the SIZE Slider. The Size Slider only goes in 100 units at full slide to the LEFT to get smaller or RIGHT to get larger.

(I used the Size slider to the left 3 full times. which was 300 units) The only thing I wanted to do here is to reduce the size of the 3DSMAX model to a comfortable size for ZBRUSH.)

5.  REMEMBER HOW MANY TIMES you moved the SIZE Slider!!!! Very important!!!

6. Do your MOJO or whatever you are detailing in ZBRUSH.

7. Decimate your mesh in ZBRUSH

8. Finally use the SIZE Slider back to the right 3 times.

(This will bring your model back to the the size of what originally came from 3DSMAX)

9. Export as a OBJ or GoZ your mesh back into 3DSMAX

10. IT WILL MATCH PERFECTLY!!!!

11. Have FUN!!!

[Kidd_Kosmonaut]

Nice, thanks for the simple solution!

[Anonymous]

When you use a 3d application they have a preferred size for optimized use. If you deviate wildly you are going to have issues with viewports, tools and the end export of the model for sale or to clients. The huge advantage of using zbrush in combination with 3dsmax is that you can set up the scale (really easily) once, and then hop between the apps as often as needed without the hassle of changing settings.

Just for a standard character you can easily have 30 subtools if you use the method I described you only have to do it once and the model is optimized for use in zbrush and max, maya etc. Not only that but if you save the subtool or project the export settings get saved along with the file. I dont really see the advantage of resizing three times then resizing back every time you want to goz one item.

[Anonymous]

Its been awhile since I looked at this thread. I still have been trying to adopt your method. I can not seem to get it to work the scale is always not correct.

Playing with the Export values in ZBrush really takes me a long time to just even get close.... but not exact to the scale from 3DS MAX. The values when playing with the export scale range from 0 to 10000. Of course it takes no time to get close but it is not exact. values like 24.3315 even makes matters worse when dealing with 0-10000. Over and over I have tried your method, probably 50 times by now at this later date. I really wish ZB would have a UN-Unify button that would rescale my model back to its original scale size.

    But from what I understand about Unify in ZB work exactly like scaling  on the x, y and z axis. It just scales the object to a size in ZB that is within a certain set of values in order to be comfortable if you will in ZB's workspace. Programs as robust as 3DS Max, Maya and ZBrush should be able to play well with each other without all this discomfort.

Still moving the Size slider method works for me. But I really wish I could get your method to work. Please do a video on youtube of your method and I will do one of mine. I could do a video of me trying your method and you can tell me what I am doing wrong. LOL I don't know what else to say. I have banged my head on this problem for a 2 or 3 years.

As for deviating wildly I agree with you. But when using my method all you are doing is returning the mesh back to its original scale in which it originated in 3DS Max. So I am not really going all that wild. One thing we know is the Unknown Values of the scaling that the Unify Button does to your model. The Export scale values are equal to that unknown value. Which range from 0-10000 and tenths, hundredths and thousandths of values in between. Which playing with SUCKS and never has taken me a minute to do and never ever has worked exactly.

Thank you again for showing your method maybe you can some how get it thru the thickness of my cranium.

Thanks Max3d2 

[Anonymous]

Hi

Ok. I just sent something from blender (using GoB) that is an environment piece and it came in pretty big, cause it is big. Unifying the model shrunk it a lot so I just left it at the original size and GoZeded the thing back to blender and it was exactly the same size as it left. So I saved the tool and everytime I pull something back or forth the size stays the same.

If I am making a character and I want it to be 180 cm tall I make a cube in Max and sent my zsphere (or dynamesh) unifyied base to max with GoZ and twiddle with the export settings till I have it pretty exact. Save the base mesh tool and the export settings are saved with it. If I want to model assets for the character in Max (and I always do) I send a decimated version of my hirez character to max (derived from the base mesh remember) model stuff around and on top and when I send from max the size and position in ZBrush is exact.

So the two situations are different. The first I am using a model with real world sizes that I created externally and just left the ZBrush settings at default. The second I sent a model started in ZBrush, unified it and adjusted the settings till it was pretty close. If you want exact measurements then you have to use the first method. If a client wants a character in a game to be 180 cm tall then the second method works fine. If I had to do archiviz (perish the thought) then I would have to use the first approach because 1.4235 millimeters will stay that size once I go from an app where I can make measured models and back to that app. I wouldn't unify that model though. I would just have to live with the scale in ZBrush.

Hope that helps.

[Anonymous]

I can get it pretty close using the Unify method. I just cant get it dead on vert on vert. I which someone would write a plugin that would show the exact values Unify does to the model. Then I could have a exact value for the export back into Max. I was playing around with the teapot in Max. The teapot's original axis is in it's base not centered. I usually re-center the teapot's axis since when you Unify in ZB it re-centers the axis. I see your point with the two scenarios very good examples. Thanks for the quick reply BTW!!!

max3d2