PDA

View Full Version : Displacement Maps in ZBrush


JeremyJessup
03-13-2006, 08:36 PM
I just bought ZBrush and am trying to model a dinosaur with it. I created the base/low poly model in Max 8 and converted it into an OBJ file. It imports fine into ZBrush and I can add tons of detail and it will re-export to into Max just fine (but with millions of polys).

I started over, and used the Projection Master to create displacement information for the mesh (planning to use the texture in Max when I'm done so that I can animate it). The problem is that I can add the texture using the alpha material and it looks great, but when I 'pick up' the model it looses almost all of the detail I added in.

I've tried increasing the poly count on the mesh to compensate for the detail (which I thought wouldn't matter, since the texture was already at the highest level ZBrush can make). This helped a little, but it's still a mess and doesn't have any of the sharp edges it needs (it's dinosaur and I'm trying to make scales... kinda needs to be detailed).

Can anyone help me? What am I missing?

(If this issue has been posted before and I missed it after doing my searches I apologize.. please provide me a link to the thread where this is covered if that's the case)

samoel
03-14-2006, 01:56 PM
i have same problem .:cry:

JeremyJessup
03-14-2006, 04:01 PM
The sad thing is that I can add all the detail and it looks fine... so long as I model it in. It's just the maps that are giving me trouble (and yes, I do have the texture set to 4096x4096). I just don't want to give my computer a heart attack when I bring the mesh back into 3DS Max and it sees tens of millions of polys.

samoel
03-14-2006, 06:11 PM
don worry dude
i know what you say and im looking for tutorial about displacemap ! if i will find this . i send to you

krolichka
03-14-2006, 06:34 PM
you have to increase the detail a little bit more. if you do a full body and lets say you try to give details for the head, the head itself doesnt have enough polys. if you hide everything but the head (if you try to use projection master for the head) and look how many polygon the head have, you will see that it includes just a bit of the whole body.
you can go down to the lowest subdivision after you have divided your mesh, and in your lowest subdivision and just the head visible divide it again. thats how you can add local subdivisions for your mesh. Digital tutors has a free tutorial on how to do this at http://www.digitaltutors.com/digital_tutors/video_details.php?v=730

can you post a picture and tell us how many polygons it has.?

krolichka

JeremyJessup
03-14-2006, 07:27 PM
Maybe I'm goind about this all wrong... I may just not understand how ZBrush looks at it's geometry. I'm trying to maintain a lower poly mesh and to add detail just with Displacement maps. Does ZBrush consider the edits of the subdivided mesh to be something which can be exported as the displacement map or is it supposed to be part of the texture that is applied as a displacement map?

I'm not at my home system at the moment, but I'll post a pic later on with that info. I'm creating a dinosaur called a maiasaurus for an Australian company. It's volunteer work, but I want to make it into a portfolio piece. I'm trying to get a lot of detail into things like scales, but when I add this through the subdivision surface and bring it back into Max it has a HUGE poly count... select sub object Vertex and the whole thing goes blue (no gaps between the verticies)

Can you create a low poly object and keep the detail high with a displacement map or do you have to actually model in all the detail? What am I missing?

(and by the way... thanks for the link)

JeremyJessup
03-15-2006, 03:26 AM
Okay... an update from home here...

The ZBrush mesh has 1087232 polys and the original mesh in Max had 67952 polys. I have attached two images... not finished models by any stretch, but a rough idea of what I am building and of what sort of detail I'm trying to get.

I want to get the Million+ poly detail into a displacement map that I can use on the 70k model in Max. Do I need to use ZMapper for this?

:shrug: I'm open to suggestions.

pnoland
03-15-2006, 10:03 AM
Basically the workflow is like this

1. Create the low poly model
2. Either create the uv map with max or let zbrush make GUV tiles or AUV tiles after importing
3. Subdivide and paint your details & use projection master for fine details
4. Tell Zbrush to create a texture map (the larger the better)
5. Set your subdivision level to 0
6. Go to tools > displacement and set your displacement settings
7. Press create displacement
8. Export the newly created alpha (this will be your displacement map)
9. Export your base model (if you did not create a morph target you'll want to use the zbrush model)
10. Import both in your render app (you may need to flip the map vertically)

If I can i'll capture a quick video of the process if I can find enough space on my server to host it.

JeremyJessup
03-15-2006, 01:34 PM
I think step 3 is where I'm having trouble. The fine detail looks great in projection master, but when I pick up the model again it gets all distorted. The color any fin lines that have been drawn look fine, but any displacement that I did (2.5D drawing) looses most of it's resolution.

Are you saying to not use Projection Master for the detail modeling, just for the painting of the textures and the like and to actually model in the higher detail an export that seperatly by creating an alpha of from the detail modeled in the high subdivision?

pnoland
03-15-2006, 03:27 PM
Well what I like to do is try to do most of the bulk detailing with just the STD tool outside of the projection master but when I need ultra fine details I will use the Projection Master. From the sounds of it you do need to subdivide more before you paint those fine details if they aren't coming out as crisp as the do in the PM. OR, it could be your uv map if the detials go away or show up funky on the model after picking up.

Edit: ACK! Had to take video down, saw something that I shouldn't have shown in the video...damn NDA's...

aurick
03-15-2006, 04:26 PM
It sounds like you're actually failing to grasp a rather critical point:

Painting mesh displacements using Projection Master is NOT the same as painting a displacement map. Creating the displacement map comes later, after you've finished detailing the geometry of the high resolution model.

When using Projection Master, your are dropping the model to the canvas as pixols. Pixols are the same size as the pixels on your screen, and have no relation to the size of your polygons. A single polygon could actually encompass dozens or even hundreds of pixols depending on the scale of your model when you drop it! All of the details that you paint using the 2.5D brushes are also being painted as pixols. When you finally go to pick the model back up, though, ZBrush must analyze the pixol detail and try to displace the polygon geometry based on those pixols.

The bottom line is that details sculpted via Projection Master's mesh displacement features cannot be smaller than the polygons that they are being projected onto. Any details that are too small for the polygons will be lost.

If you think about it logically, you'll see why this has to be. After all, if you could use Projection Master to sculpt details of any size regardless of polygon counts, then there would be no need to divide the model in the first place. :)

JeremyJessup
03-15-2006, 05:28 PM
Excellent... I bought ZBrush last week and am still trying to get some of the basic concepts down. Thanks for clearing that up.

One other question though, in Projection Master you can use different types of brush strokes to control depth (layer brush) or create patterns (with the Alpha material) Is there a way to incorporate this type of control into the general modeling process or is it all controled by the draw size, focus control, ZDepth, and a steady hand?

pnoland
03-15-2006, 05:44 PM
I don't believe you are able to use alpha's with the std brush and other edit brush tools (dot, inflat...etc) but that is why you see users mixing PM with normal displacement painting.

Matt, thanks for the explination too, I always forget to bring up that point when talking about the projection master.

yolao
03-15-2006, 05:52 PM
The fine detail looks great in projection master, but when I pick up the model again it gets all distorted.


i have the same problem but when i want to paint bump map...and this happen with a geometry with all the uv`s layout properly in maya...some of the strokes get distorted after i pick up and some fine details disappear completely.....and with a texture of 4k x 4k

samoel
03-16-2006, 04:07 PM
hi dude

do you have render man ? i find good tutorial for do this and now im so happy cause i don have any problem for render zbrash model with displasment map in maya with renderman . if you have renderman for maya 7 you can render your model in a few second .last night i render my model with 2000000 polygon only in 5 sec by renderman

http://www.animationnewport.co.uk/phpBB2/files/01_896.jpg


i want to make tutoril movei about this . i think this tutorial will be so helpful for anybody that they want do this.
i will come back soon with my tutrial

CGTalk Moderation
03-16-2006, 04:07 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.