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View Full Version : Importing bump map from Zbrush...getting tiles showing up...please help...


Kahwatikid
03-27-2005, 04:36 AM
Hi folks...

I've just brought in a model from Zbrush ...actually from xsi to zbrush and back....I decided to do the quick 1 - 2 UV mapping method in Zbrush...which creates an awful lot of tiles...anywho....I tested out my maps in Maya (which I'm currently migrating from) ...and everything worked out fine....except for the fact that Maya sucks ass at handling Sub-d's....so I wanted to bring it into XSI.

Anyway...I know that I plug in my texture through a "Bump Map Generator" node....into my Material...thats cool...but all the borders for my Bump map are showing up like crazy...and I dont like it (obviously). I've tried playing around with the "Bump Filtering" with settings like "Max. Eccentricity=.05(sloooow) max pixels for min =1 and bilinear interp on....etc....actually none of it really made any difference....

I really dont know what to do...Can anyone help? Pleeeeeze?

Also....since I've got you here....I do add a custom geometry approximation for my model's displacement map.


Thanks...and happy Easter!

JDex
03-27-2005, 04:49 AM
If memory serves, you need to rotate the image in PS or another editor... Zbrush UVs are flipped the wrong way per MR. See the big honkin thread at zbrush central where RRay describes the process in detail. Sorry, no link at hand at the moment for you.

Finkster
03-27-2005, 06:26 AM
Yep, flip the map vertically (just go to the image PPG and do it there, but if you do it in photoshop ensure that color-profiles are not attached to the image). For finest displacements, you'll probably want to use geometry approx. with fine displacement, view dependence checked, with refinement of 1 pixel, or maybe less. If you want the most accurate results, turn render-region progress reports on, you can adjust the displacement recursive steps until the triangle-count closely matches the poly count of your dense mesh in Z-brush. Polymesh sub-division render level should be at least 2.

Kahwatikid
04-01-2005, 04:40 AM
Yikes! I've been away for a while...sorry about that....Thanks for your quick response Finkster!

I actually tried all that...and it did help with the displacement mapping...but I then thought it could just be because of my crappy uv mapping job (auto mapping in Zbrush on a model made in Maya)....it was quick and dirty...and I know that there are consequences. But I re-did the UV map (still using the auto system...just this time with bigger pieces)....and it all worked fine and dandy in Mental ray for maya...but in Xsi's render...even without using my displacement map....just with colour and bump...I'm seeing tiles from my texture borders. In maya I believe the way to allieviate this problem is by lowering the filter values...but XSI doesnt have filtering on by default (or does it?). Anyway, I've attached a pic of the problem.

PS...the maya one has a sss shader on it ...thats why it looks the way it does.

Kahwatikid
04-01-2005, 04:46 AM
Yikes! I've been away for a while...sorry about that....Thanks for your quick response Finkster!

I actually tried all that...and it did help with the displacement mapping...but I then thought it could just be because of my crappy uv mapping job (auto mapping in Zbrush on a model made in Maya)....it was quick and dirty...and I know that there are consequences. But I re-did the UV map (still using the auto system...just this time with bigger pieces)....and it all worked fine and dandy in Mental ray for maya...but in Xsi's render...even without using my displacement map....just with colour and bump...I'm seeing tiles from my texture borders. In maya I believe the way to allieviate this problem is by lowering the filter values...but XSI doesnt have filtering on by default (or does it?). Anyway, I've attached a pic of the problem.

PS...the maya one has a sss shader on it ...thats why it looks the way it does.

I also forgot to thank you too Jdex...thanks

desiredfx
04-01-2005, 11:48 AM
dunno if it will help this but try making bump/displacement image into 8 bit. XSi seems to have probs with 16 bit tiff etc.....

Strang
04-01-2005, 03:59 PM
kawhatikid

let us know what the solution is.. k?

Kahwatikid
04-01-2005, 09:13 PM
well...I'm royally confused.

Is there anyway of telling XSI to handle how it looks at UVborders differently?
This seems to be a UV problem more than anything...and I'd go and re-do it all if I hadnt seen it work perfectly in Maya with the exact same model and textures.

AAAARGH!

Strang
04-01-2005, 10:15 PM
i believe wurp had a problem with disp mapping and discontinous edges causing trouble.. search for that. i am unsure if they came to a conclusion

Kahwatikid
04-01-2005, 11:51 PM
k...so I've attached an image that may illustrate the problem a bit better. What I've done here is just pumped up the bump map numbers...just to intensify the problem. You'll notice the wierd banding where my bump mapping is having issues. It almost looks like the bump is going in different directions for each uv patch.

Strang
04-02-2005, 02:24 AM
so maybe you need to work out the UV problems on a simpler model. make sure your following very similar steps

maybe isolate the problem. maybe its going in between apps. maybe XSI needs something a bit different from zbrush

just an idea

Finkster
04-02-2005, 02:52 AM
A few obvious questions:
- is the clamp option checked?
- have you tried resetting the steps values back to the default 0.001?
- have you double checked you have assigned the bump map to the correct texture projection?

I don't know what else.

Sorry.

Kahwatikid
04-02-2005, 03:01 AM
thanks anyway folks!

I figured that this would be a simple fix....since it the model and textures work flawlessly in Maya and Mental ray in maya. It just seems to be the way XSI is handling the UV's. I was even able to resolve the issue with the inversing patches....though I'm still having issues with borders showing up in the bump map.

Cometsoft
04-02-2005, 03:06 AM
For displacement in the render tree I've been using the method in ZBrush Practical guide which uses the change range node. I use the alpha factor from the ZBrush alpha displacement instead of an intensity node. So if the alpha factor is .048 I put in .48 and -.48 in the new range start and range end. I've also had some success with a method using two basic math operations of a subtract and divide. If you search in XSIbase you can find an example.

For geometry approximation I usually use fine with a length of around .025. I've used both ZBrush adaptive UVs and XSI projections. Obviously the adaptive UVa are more efficient but imposible to read in Photoshop.

I thought the whole thing was working pretty well, but for some reason the last model I was working on develped some ugly seams. On the other hand it has worked fairly well in other cases. The 16bit displacement maps seem to work ok. Haven't really messed around with bump maps much. There's a lot of stuff at ZBrush Central on it too. Also Practical Guide says to use the smooth uv option when subdividing in ZBrush. Haven't noticed any difference.

The bottom line for me is that there is a little too much voodoo in the whole process but it works well enough that I can't stop trying.

I just put a bumpmap on a model with displacement and there were no seams. Took ten minutes. A 2048 image, using just the default bump map generator plugged into the surface. What happens when you put a ZBrush solid 50% grey image on the model? Maybe throw a few simple bumps on just to see what happens.

legylion
04-02-2005, 06:47 AM
I'm having the same problem moving a recent model back and forth between xsi and zbrush. It is pretty obvious to me that xsi is having a tough time reading the "AUV tiles" back in xsi. If you look at the attached example the UV seams are clearly evident when I plug the map into the bump map generator. The tiling isn't nearly as prevalent when interpreted as an actual displacement map but you can vaguely make the seams out if you look very carefully. I've pinned it down to two possible conclusions: Either "Smooth UV" when subdividing the model in zbrush is having some kind of adverse effect or else the bump map generator in xsi doesn't like the "AUV" tiling solution. I suppose it could be both. To be honest I'm just as stumped regarding this problem as you are. I'm going to build some simple models and try different displacement set-ups in zbrush to see what possible differences they might present when exported into xsi. If anyone comes up with another theory regarding this mystery in the meantime I'd be more than anxious to hear it. Cheers.

JDex
04-02-2005, 07:04 AM
Are you guys converting (manually or auto) the bump maps to .map files and/or using elliptical filtering?

legylion
04-02-2005, 07:23 AM
I've never converted to .map using bump maps. I've tweaked the hell out of the elliptical filtering settings to no avail. Is there some advantage to the the .map format in this instance that I don't know about?

JDex
04-02-2005, 07:55 AM
Sorry, I should have been clearer... Eliptical filtering is bad on bump/disp maps in my experience... especially with Unique UVs or lots of UV patches... if you just have 2 or 3 seams you can get it a little better... There should be no benefit with .map files on bump/disp unless they are large and are causing memory issues.

Cometsoft
04-02-2005, 12:35 PM
legylion-
Are you using a bump map generated from the displacement tab or a texture file using BumpViewerMaterial? I like the latter. If you're using the first method maybe you could convert the alpha to a texture, go back to your base mesh and load the BumpViewerMaterial and see what's going on.

I liked the idea of the auv tiling, because you don't have to layout uvs. But in light of the inconsistencies am going to stick with XSI texture editor. I agree with you that those auvs may be a source of problems.

Strang
04-02-2005, 06:36 PM
but this is a bummer. cause the auv tiles seem to work well in maya.

while at GDC. i was in a conversation with someone that sat down with pixolator (dont know real name) and asked about whats going on at Pixologic. basically i understood it Pixologic is going to work a bit closer with DCC apps to get better and easier results back and forth between the 2 apps.

it makes sense to me that maya works well because of Weta and Pixologic working closely to get Zbrush 2 up to production standards.

my 2 cents

-Steven

Kahwatikid
04-04-2005, 12:12 AM
I guess I have an update for all those who care....the image in posting 11 was from an obj that I imported into maya first then re-exported as an obj into XSI. The reason for this you ask? Well I noticed that whenever I brought in an obj directly from Zbrush....in its poly state the model was all blackened and burnt looking...untill I hit the + sign to convert to sub-d...then it looked fine. I also found that the model looked faceted when I brought it into maya, then in maya I would convert to sub-d then back to poly (vertice option on)...and it would give me the same polygonal mesh this time without the hardened looking normals. As mentioned before that in Maya ...even after I did this...things worked swimmingly.

Now, when i brought in that obj from maya...I would get wierd issues with inverting values (for my bump maps only)...and that drove me crazy...as you can see above. So then I brought in my original obj from Zbrush that looks all ugly in poly mode....and did a quick render....and it looked fine...but again I still had some wierd issues with the UV seams showing up only in the bump map (mind you they are visible in my colour map in any GL texture view...but not in the renders...or soo fine that they're negligable). It seems to be just an issue with xsi reading the crappy auv's from Zbrush. I still love xsi ...I just feel like beating it over the head right now....aaargh.

Anyway, thanks folks for all the help, and listening to the rants! I'll keep this posted just in case I figure something out. A friend of mine who's pretty expertful is going to be looking at it.

L8r Sk8rs

JDex
04-04-2005, 12:19 AM
Your "blackened" poly issue is a known issue... import your .obj direct from Zb and in the explorer expand the stack and open the Clusters container... delete the User Normals cluster... and things will be better (at least that issue, but it may fix some of the others).

I know people have had success without the issues you are facing between Zb-XSI, so I know for a fact that it can be done... but I personally have never used Zb2 yet, so I can't help too much.

Kahwatikid
04-04-2005, 12:51 AM
Hey man...thanks for the info!

Thats something I can definitely put to use right away...right on!

Kahwatikid
04-04-2005, 12:54 AM
Hey Jdex...would you by chance know of a step by step idiot proof tutorial on how to apply displacements properly fromZbrush? I tried looking on Zbrush central for one...I found buttloads of maya ones ...and I did find something neat in the Zbrush Practical guide pdf...but it wasnt practical or idiot proofed enough.

JDex
04-04-2005, 01:35 AM
The only thing I really have done was the test files in this (http://206.145.80.239/zbc/showthread.php?t=20310&page=1) thread at Zbrush Central using RRay's posts as a guide... he also in one of his posts later in the thread links to another thread where he shares other details (if memory serves correctly)... Zb is something I probably won't get into personally until next year.

Hopefully this will help a bit, and keep us posted... I agree that there needs to be a difinitive guide to the process.

Kahwatikid
04-04-2005, 02:01 AM
ha thats funny...I just hit veteran status with my last post....I was wondering how you change that line

Finkster
04-04-2005, 07:03 AM
It looks like there are bump map seams alongs any discontinuous UVs, whether they are Zbrush created AUVs or not. I've tried painting a continous bumpmap on a cylinder mesh, with plain cylindrical UV mapping (done in XSI) and I get clear seams along the discontinous edges. The funny thing is, if you examine each UV vertex that shares the same point on the mesh, according to the texture editor colour picker, they have the same RBG values, but a seam still shows up.
The problem seems (no pun intended) to lie with XSI/MR's bump/displacement, rather than with the mapping method used.

:sad:

Facial Deluxe
04-04-2005, 07:19 AM
One of the best explanation about Zbrush2XSI subject I know (Thanx to ZePilot) : http://www.xsibase.com/forum/index.php?board=6;action=display;threadid=11683

2 of my tries here as well :
http://www.xsibase.com/forum/index.php?board=5;action=display;threadid=15484
http://www.xsibase.com/forum/index.php?board=5;action=display;threadid=15376;start=0#msg101104

Ordibble-Plop
04-04-2005, 07:53 AM
Your "blackened" poly issue is a known issue... import your .obj direct from Zb and in the explorer expand the stack and open the Clusters container... delete the User Normals cluster... and things will be better (at least that issue, but it may fix some of the others).

I got around this problem by unclicking the "Normal (different normals in normal user cluster)" box in the OBJ import options dialog box before importing.

Everything seemed fine after that but I'm new to XSI so maybe doing it this way will cause problems?

legylion
04-07-2005, 06:44 AM
I have been having a similar problem with xsi reading AUV's as a bump map and have come to a few conclusions regarding this issue.

#1 (and most importantly): Tiling can virtually eliminated by rendering out a separate high frequency detailed bump map in zbrush.

#2: As Finkster has previously pointed out, xsi's bump map generator will give you tiling along discontinuities regardless of AUV accuracy.

#3: If you can spare the rendering time you are probably better off using displacement only in xsi because it can simulate zbrushe's high frequncy detail very well in fine mode.

If you look at the first image in my file attachment you will see a definite case of tiling/banding caused by using a displacement map generated at subdivision level 1 in zbrush as a bump map in xsi. This is because A: the displacement details continue across the seams of the AUV's and also as a result of having to dial up the bump map settings very high to bring out the finer details. No good.

In the second image the tiling is eliminated by switching to subdivision level 4 in zbrush (out of a possible 5) and rendering only the fine details from level 5 as a displacement. By taking this new displacement map and using it as a high frequency bump map, the tiling should now be negligible if not invisible as discontinuities have been significantly reduced.

The third and last image is used as a reference to compare xsi's fine displacement only & the displacement/bump hybrid in image 2. Please note that image 2 is rendered in xsi at subdivision level 2 with parametric displacement - image 3 is rendered at subdivision level 2 with fine displacement and view dependent checked. Also note that I've unchecked "automatic discontinuity" in the geometry approximation as I found it returned unexpected sharp edges with imported models when left checked.

I cannot be certain this will alleviate all of kawatikid's issues as I have had no significant issues regarding the colour maps I've created. I can only recommend trying "fix seam" under "texture" in the zbrush tool palette. Hopefully it will help.

If anyone has anything further to add or refute about my comments I would love to hear it. Good luck.

Finkster
04-07-2005, 01:11 PM
Those are some nice tips legylion.
Apparently the tiling is caused not because the displacement dtails continue across the UV seams (I think that is the equivalent of Zbrush's fix seams, for displacement maps), but because XSI evaluates the bump normals for a point based on neighbouring UV space, not the geometry. The cool guys at xsi base offered some solutions also:http://www.xsibase.com/forum/index.php?board=12;action=display;threadid=18299.
(that's me btw., don't ask why I go by two different names......:shrug: )

Thanks for the great help legylion!

Kahwatikid
04-07-2005, 05:45 PM
(more of a commentary than solution)

whew....I'm glad to see that its not just an issue with my scene file!

Those are all some good points...so it seems that Normal Mapping is the way to go eh? I'll give that a try. It seems really odd XSI has this wierd problem? Its so kickass at just about everything ...(except for those random spontaneous dissapearance tricks....that happen at the most important times...like when saving a file...but thats another story). Seriously, XSI is a sight for sore eyes when coming from Maya (espescially if you're in a smaller production environment), you would think that they would've had bump mapping covered better. I've heard that the way it calculated Bump Maps is supposedly far supperior than the way other apps do...well maybe then the problem is that XSI is just ahead of its times.

I dont know....I'm just ramblin folks....

I have made a normal map as well...I'll throw it on soon and keep you posted. I'm tryin to finish most of this character by tonight ....so I'll probably be askin for some opinions on style too!

L8r sk8r's

Sil3
04-07-2005, 06:45 PM
I've heard that the way it calculated Bump Maps is supposedly far supperior than the way other apps do...well maybe then the problem is that XSI is just ahead of its times.

I dont know....I'm just ramblin folks....



I dont know either but... Soft needs to make some improvements to itīs Bump Map thatīs for sure, it is so slow to render :(

Normal Maps render a lot faster than bumps by the way, almost no rendering hit...turn on bumps and grab a cigarrete :)

legylion
04-07-2005, 08:13 PM
Hi Kawahtikid,

I suppose it doesn't seem like much of a solution for you, especially for models in zbrush you may have already completed that do not conform to the described workflow. As far as normal mapping is concerned, I can only hope you experience more success than I did using them as an alternative. They look great on my low poly geometry, but artifact horribly when I raise the subdivision level (normal maps are utilized through the same bump map generator). If you find a good technique for using them in your instance give a shout. Thanks.

legylion
04-07-2005, 08:35 PM
I should probably clarify that I used the D3 normal node in my render tree. The thread that Finkster points to discusses a method for generating normal maps without add-ons. This may give you superior results.

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