Painting Textures in Zbrush to Photoshop and Back Again
By JC Cappelletti
This totorial was designed to be as easy to follow as possible. It may seem there are lots of extra steps. They are meant for beginners who need the practice dealing with UVs in Zbrush. Also, the workflow that I am following applies to people who start a model in Zbrush, or import a base mesh and use a lot of extractions in Zbrush. If you are very familiar with UVs and Zbrush already, you can skip down to Step 60 for the import and export parts.
It should be obvious enough for users familiar with Zbrush to just follow the pictures. For newer users, the text between pictures will explain every step.
Final disclaimer: The textures in this demo are meant to be quick and simple for demonstration purposes.
Step 01 - Open DemoHead.ztl
Step 02 - Under Tool click Colorize to enable per-poly 3D painting. Similar to painting in Maya with Screen Projection on but a million times better.
Step 03 - Ignore the bad color fill. Turn off Z add. We only want to paint RGB.
Step 04 - Change color to white and paint the face.
Step 05 - Change the Material to MatCap White for better color while keeping shadows on. Now you can paint something easy to test this workflow. I did clown makeup.
Step 06 - If the changing eye color annoys you. You can select the SubTool and activate Colorize on it as well.
Note that the UVs are shared with SubTools, meaning: if you are laying out UVs ahead of painting in Zbrush, The simple way to ensure no problems is to layout everything that will share the same texture file in the 0to1 standard square with NO overlapping. If you are starting your models in Zbrush, or using a lot of extractions, you will worry about this later, when it's time to export textures to Photoshop.
Step 07 - Click Colorize for the SubTool and then make sure you select the top tool in SubTools before you continue.
Step 08 - As you begin to paint closer in, you will notice the poly resolution is not high enough to do any serious detail.
Step 09 - In Tool -> Geometry, Click Divide up to 5. Any more than 5 will be beyond practical resolution limits for most people, and is definately overkill for this demo.
Step 10 - Change Stroke and Alpha and paint some sharper details to test the resolution.
Step 11 - Now we are going to test some of the UVs that Zbrush can generate internally. They are absolutely useless for painting in Photoshop, but if you will only paint in Zbrush, they are quite handy. If you don't know about them, it's important to understand what the layouts look like at least.
Click EnableUV under Tool -> Texture (not in the Texture Menu)
Step 12 - Any time you want to change UVs, you must be at the lowest Division level. You will get a warning if you forget. Drag the Division slider to 1 under Geometry.
Step 13 - Click Uvc under Tool -> Texture to see the crappy Cylindrical mapping.
Step 14 - Divisions back to 5.
Step 15 - Under Texture Menu, change Width and Height to 1024. 2048 and 4096 are fine, but not necessary for this demo.
Step 16 - Texture -> New.
Step 17 - Notice that it will fill with your foreground color. Doesn't really matter here, but I will change it to white from now on. Now, under Tool -> Texture, click Col>Txr button to transfer your painted polygons onto the UVs you just created.
Don't worry about all the poly painting you did. It will stay safe somewhere in the magical .ztl format untill you fill or replace it. This would be a great time to save your .ztl, by the way.
Step 18 - Notice that Cylider mapping doesn't work for anything but a Cylider and never use it again. Roll your mouse over the Texture icon on the Left to see a blowup preview.
Step 19 - Choose Texture Off under the Texture popup.
Step 20 - Now we are going to see two more layouts. You can try them all if you like, but the following is the most useful for internal UVs.
Set Divisions to 1 and click AUVTiles under Tool -> Texture.
Step 21 - Divisions back to 5. This is very important if you want the highest resolution transfer. Otherwise you will see giant pixel blocks.
Step 22 - Texture Menu, New. (I'm assuming you check the resolution from now on)
Step 23 - Colors to Texture again.
Step 24 - Rollover to see preview. Notice the texture transfer is perfect, but the UVs seem random and are impossible to paint on in Photoshop.
Step 25 - One last experiment. Choose Texture Off again.
Step 26 - Divisions to 1. Click GUVTiles under Tool -> Texture.
Step 27 - Divisions back to 5.
Step 28 - Texture, New.
Step 29 - Colors to Texture.
Step 30 - Preview of GUV tiles. Slightly more distiguishable from AUV tiles, but still not as useful to paint in Photoshop with all those pieces. Export this Texture.
Step 31 - Now to get decent UVs. Divisions to 1.
Step 32 - Tool -> Export to get the .obj out.
Step 33 - Be sure to save it with a name that you will recognize as needing to be fixed.
Step 34 - This is the most important step for people trying to fix UVs in Maya from Zbrush. If you miss this, your model will explode when you import the fixed UVs. So many students have missed this and wasted way too much time laying out UVs that are useless to them in Zbrush.
File -> Import -> Options Box.
Step 35 - Under File Type: Choose OBJ.
Step 36 - Here is the magic button that will solve all your exploding model problems. Change True to False. If you are using Maya 2008. There is just a check box here. Even if it is off by default in 2008, you should still go this Options box and click import under here the first time you do it. Maya Prefs will remember this option from Now on, but you should check it to be safe before starting any really important big UV layout.
The problem if you miss this step is, Maya will re-number the verteces when you import an OBJ with default options. Not a problem for Maya, but Zbrush uses those precise numbers to update UVs when you import the model back in. This means you can't do any Poly Modedeling at this point or it will change vertex numbers and make your UV layout useless. There are ways to import model fixes late in the game, but that is another tutorial.
Step 37 - Notice the UVs. Every polygon is stretched to a perfect square. Yikes!
Step 38 - Under the Polygons menu set, Create UVs -> Cylindrical Mapping.
Step 39 - Change the 180 to 360 in the Chanel Box or drag that little red box on the mappin gizmo around all the way. This will keep all the UVs inside that 0to1 default space and keep Zbrush happy. You can Cut and Sew that tag in the top right if you want. Sorry for the cut off screen.
Step 40 - In the UV Window, make sure you are in UV component mode (F12) and choose Polygons -> Relax -> Options Box. Click apply several times until most of the undercuts around the ears and chin are gone.
Step 41 - You can unfold these UVs if you want the nose to be better. Obviously you can spend a lot longer laying out this head properly, but this is useful and quick.
Step 42 - Make sure the OBJ export plugin is on. Somehow mine is always off.
Step 43 - Check both under objExport.bundle.
Step 44 - Make sure you are in Object Mode and Export Selection. Save this file with something really obvious that this file is Fixed UVs.
Step 45 - Divisions to 1 if not already.
Step 46 - Import to get fixed UVs.
Step 47 - Be sure to choose the correct file. This will be your Master UV file that you can import every time you turn the UVs off and on again in Zbrush.
Step 48 - Old Texture with the New UVs. Notice how Zbrush makes Alpha masks out of the pure black. Not very useful. Now we will transfer the poly painting to the new "good" UVs.
Step 49 - Texture OFF.
Step 50 - Divisions to 5. If your Model ever explodes at this step, your Maya settings weren't fixed and you need to layout UVs again. Go back to step 34 and read carefully.
Step 51 - Texture Menu -> New.
Step 52 - Colors to Texture.
Step 53 - Preview of texture.
Step 54 - Texture -> Export to get the PSD file out.
Step 55 - Do something in Photoshop. This is just a quick Hue shift and texture filter to prove the point. Save as a new file name. PSD format works best.
Step 56 - Import the texture you just made in Photoshop.
Step 57 - New file.
Step 58 - Transfer Textures to Colors. This will put all the stuff you did in Photoshop onto the poly paint in Zbrush so you can take it further with other methods if you like.
Step 59 - Texture Off.
Step 60 - Now choose a texture that you want to paint with.
Step 61 - This is why you need to Disable UVs before you can paint with textures. This seems to be annoying at first, but it makes more sense once you know how it works.
Step 62 - Texture Off and Disable UVs.
Step 63 - Change your stroke to DragRect. Pick a soft round Alpha, and choose a texture to paint with.
Step 64 - Drag and rotate and notice how well this would work if you took some time and prepared proper skin and hair base textures ahead of time.
Step 65 - You can get a lot of randomness with even one simple texture. This works incredibly well on skin.
Step 66 - Try a few other textures for fun. This also works well to test your texture resolution.
Step 67 - One more texture.
Step 68 - This is the second most important step. Before enabling the UVs agian, be sure to turn OFF the Texture first. If you forget, you may be lucky enough to get an Undo. Just don't forget.
Step 69 - Enable UVs.
Step 70 - Divisions to 1.
Step 72 - Import the same Fixed UVs OBJ from before.
Step 73 - Divisions back to 5.
Step 74 - Texture, New.
Step 75 - Colors to Texture.
Step 76 - Preview of new Texture.
Step 77 - Congratulations! Now you don't hate painting in Zbrush anymore. To get full marks for this assignment, I need to see the last three of these PSD files.
