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Retopologize Problem

ZBrush Usage Questions
#1

Hi,

i'm working on a human character in ZBrush 3.1. Currently i'm at SubDiv Level 6 and i need to retopologize my mesh now. I have exported my BaseMesh into Maya and made some fixes on it. After reimporting it and projecting my HiRes onto it I got some strange results. To be shure that it was not my mistake i tried to project the HiRes Mesh onto a clone Mesh of itself but still got the same result. Here is a screenshot of my HiRes: [img]http://users.fh-salzburg.ac.at/%7Efhs15014/before.jpg[/img] A screenshot of the "LineUp" before projection: [img]http://users.fh-salzburg.ac.at/%7Efhs15014/line_up.jpg[/img] And a screenshot of the result after projection: [img]http://users.fh-salzburg.ac.at/%7Efhs15014/after.jpg[/img] Has anybody some tips on what is going wrong here ? allie
#2

ok, so here’s what i found out so far. i started my model in maya and imported it into ZBrush without concerning the uv layout. In ZBrush i added some edgeloops to it. again without thinking about the uv. I did some research and found out that maybe a false uv layout might be the cause for my retop problem. so i checked my uvs in ZBrush and saw that there were some parts on my model without uvs so i quickly added a circular uv to it in zbrush. after that i tried again to retopoligize by projecting the HiRes onto it’s unmodified BasesMesh (e.g. a clone where i deleted all SubDiv Levels). Additionaliy i switched ProjectRange to -1 because i also read that this could help sometimes (for no reason ?). indeed it helped but still got some random polys in the head section. so i did some more research and found out that ZBrush sometimes can’t handle holes in the Mesh, like in the eyes, ears and the nose and a way to get around this is to push the edgloops around the holes more away from their nighbouring edgeloops. Did that but still got random polys when retopologizing. So i tried to export the BaseMesh into Maya; Did some changes to it, created an automatic mapping for the UV and reimported it to ZBrush. Then i took my HiRes and projected it onto my new BaseMesh i just imported. And guess what ? It didn’t work! It just crashes ZBrush because ZBrush says i have way to much polys which my system can’t handle.

Ok, but still motivited to go further. I tried to retopologize the Head section in ZBrush but had to face the problem the ZBrush won’t let me zoom in enough so i can’t work on the eye, and nose section. Did again some research and found some tips that again didn’t work.

and NOW! i’m close to insanity!! is there any method out there that does really work to get this retop running ???

#3

i made a new uv map in maya with automatic mapping and imported it back into zbrush at SubDiv Level 1. Now the projection works fine except for the head:

The problems are just the holes now. Please, is there any workaround for this without starting from scratch ??

allie

#4

ok, tried something else. I have exported the model and filled the holes in maya. reimported it and did the projection again but still got this random polys only at the spots where the holes used to be!!

Any advice ???

allie

#5

Have you given this thread a read? http://www.zbrushcentral.com/zbc/showthread.php?t=44876

#6

i do know it and read a couple of posts. but there are about 44 pages in total and i didn’t have the time so far to read all of them. but i think i have to. apart from that it is really difficult to find some more help with the search engine. this is the 3rd day now and i still haven’t found a solution. by now i’m really disappointed from this forum.

#7

even though i didn’t find the solution in here i still got it done. so here’s what i did and what i had to struggle with.

first, the main problem was that there's an obvious problem with ZBrush handling geometry around holes. there needs to be a huge update in the future or ... whatever. the way to get it all the same running is to keep the geometry around holes as short and as clear as possible. in my case i had some edgeloops pointing way to far into the model. to get that straight i have holes for the eyes, the mouth, the nose and the ears and i even have an oral cavity but the geometry right near to the hole itself needs to be "clear". that means no overlapping and no distorted polys. In my case the distorted polys caused the biggest headaches. another major issue was that ZBrush has huge problems with zooming in when retopologizing. In my case i needed to get that close that ZBrush couldn't handle it anymore and stoped at a particular distance. So i had to do the re-top in Maya. And here comes the next problem. You need to be very careful when you're changing the vertices outside ZBrush. I don't know if it's a common problem but the topology may not be changed in the z-axis, that means you even can delete points and create new polys, but you can get strange "spikes" when projecting the HiRes onto the new topology with vertices altered in z or with vertices that don't meet a vertex on the HiRes. According to some threads here, the zooming problem could be fixed with a workaround, by positioning the model in preview mode and working on it in edit mode without clicking outside the model. In my case this didn't work. instead it crashed ZBrush everytime i tried it. The reason why i had these spikes in the area around the legs was because the uv layout here was a real mess, actually it didn't exist at all - and not only there. I made a new one in Maya and reimported it into ZBrush. The spikes around the legs were gone after that. But the automatic mapping i used to create the uv-layout wasn't as good as i thought in the first place because you get some tiny stripes along the uv-seams after projecting the HiRes onto the new topology. I still don't know how fix this without smoothing them out. Another problem I ran into was the common problem which usually happens around toes and fingers. In my case it happend around the toes, that means it was destroyed by random spikes. I found a workaround for it where you leave out the area around the toes when retopologizing. But i didn't understand how this could work. Maybe someone could explain it to me, but according to the process my thread made so far... whatever, in the end I just smoothed them out. Ok, maybe someone will find this useful in the future.
#8

The problems mentioned in this thread iv posted about a few times hoping that somone mite have a answer. There is a major problem with holes and this stops me using (Project All) from the Sub Tools menu.

The only time I get to project my details fine is when I make a new topology, providing I keep the fingers and toes from the original mesh that is. Zoom issue is also a very anoying problem and has stoped me making fingers, toes and inner eye lids e.c.t. Im having to go in and out Zbrush between other applications to part build the topology in Zbrush, and part in Modo.

To top this all off I cant even export my model and create Uvs without Zbrush folding up my mesh when moving to a higher sub d level. I hope the Mac version dont have these issues even athough I dont actualy have a Mac, mac users have waited a while now so thats hope a update comes with the Mac and one for Pc users.

#9

glad i’m not alone with these problems. by now i’m really surprised that these issues are that rear discussed in this forum.

@ tez, how exactly is your workflow when you’re retopologizing your mesh outside ZBrush? I really have to rethink mine now, because i just figured out another problem: It’s impossible for me to project a HiRes Mesh to an unchanged LoRes clone without getting this random spikes. that means: within zbrush it’s absolutly impossible to build a new topology that works without any troubles when projecting a HiRes Mesh onto it.

#10

allie, iv been hitting my head againts a brick wall for months now, and am sad to say that some of these wonderfull hopes of using ZB3 features, are totaly out of the window at this moment in time.

Its was only natural to think that I was being fussy or un educated in the usage of these new tools, but carefull reading of the wiki showed me that I was doing nothing wrong. What did get me was that I also dont see many of the same problems reported which leads me to think that nobody els is using these tools like im trying to use them, (as they where promoted).

I would asume that a very skilled modler which I hope to be one day, can build such perfect topology that he/she would never have to go back and change anything. In my case, im learning better routes of topology day by day, but Zbrush isnt doing its job in assisting me achive this.

I can not get close enougth to do fine topology in Zbrush, I can not project any detail back on a mesh with open eyes or mouth holes, and I can not project any detail back if I re-import the base mesh with new Uvs.

The Zproject Brush athough im working on the model bit by bit, and directly in front of me, fails me every single time with spikes and ripped polys. The symmetry on my hours apon hours of sculpting gets lost and can not be corrected with smart sym. I now have to follow this route.

  1. Make base in external application. To save time it wont have great edge flow, much like a base mesh Zack Petroc makes for alot of his sculpts

  2. I form the sculpt proportion and very low level detail, then build new toopology. I will keep the hands and feet of the base mesh as my starting point for the retopology.

  3. Next I will export the base for editing in a external application, adding more edge loops, clean up the mesh more and build any additional geometry needed like inner eye sockets and mouth.

  4. Once im happy with the base I will make new Uvs.

  5. Zbrush gets back a fully prepaied base mesh with no details. I then start adding details within several Sub D levels. I save regular in case I loose symmetry.

  6. Finnaly I will make my displacment maps, Normal maps and and texture maps.

Rendering is done in finnal application. I can in no way rely on any Zbrush detail projections. The details only get added when the base is fully created, this is basicly the way I had worked in ZB2. I have total faith that Pixologic is dealing with these issues as we speak.

#11

thanks tez. as you said, this way basicly relys on knowing the forms you’re going to create before you start to sculpt them in ZBrush. And i need to do a lot more sculpts to get that right. But for no reason (this is my first human sculpt in ZBrush) i spent a lot of time in maya to build a clean topology before i put it into ZBrush, using Zack Petroc’s final BaseMesh as a visual guide. But as i found out afterwards, i’d better spent a little more time in Maya. I guess we have to wait until pixologic comes up with the next huge update until we can use their new projection features as they were meant to be. But I think in the meantime you’re method is a good way to get around this tools.

so thanks again for sharing it.