Polypainting

Polypainting allows painting on a model's surface without first assigning a texture map. A texture map can be created at a later time, and the painted surface can be transferred to the map.

Polypainting offers significant advantages compared to standard workflow:

• The resolution of the texture map need not be decided in advance. This is particularly valuable if you find you need more detailing on an area than you thought you would. Instead of repainting a new, larger texture map, you can simply transfer the existing surface painting to a new, larger map, with no rework necessary.
• Similarly, the UV unwrapping need not be fixed in advance. If one unwrapping proves unsatisfactory, simply create a different unwrapping and transfer the surface painting to that map.
• Removing UVs from your model frees up system resources and allows you to work with more polygons.

To see an example of PolyPainting check out the First Painting page.

Contents [hide] 1 Poly to Pixel Ratio 2 Set Up Your Model For PolyPainting 3 Painting With Your Sculpting Brushes 3.1 Control the Shape of Your Brush with Alphas 3.2 Control Your Brush Stroke 4 Using a Texture Map to Paint with in ZBrush 5 How Do I Work With A Texture Map in ZBrush? 5.1 Baking a Texture Map to PolyPainting 5.2 Baking PolyPainting into a Texture Map

Poly to Pixel Ratio

To understand how polypainting works, first consider a 2048 by 2048 texture map, which provides reasonable resolution. It has a total of a little over 4 million pixels.

The new version of ZBrush is fast enough to handle models with large polygon counts. If you work with a 4 million polygon model, then in terms of surface painting, simply assigning each polygon a uniform color gives the same amount of information as the 4 million pixel texture map. (Actually, somewhat more, since significant parts of texture maps are typically left blank.)

So, with polypainting, you can put all of the painting details directly onto the model's polygons, and then transfer that detail to a texture map when the painting is complete.

Set Up Your Model For PolyPainting

Remember three points when using polypainting:

• Polygon colorizing is enabled in ZBrush when the Tool:Texture:Colorize switch is on. It is off by default, so remember to turn it on before starting to paint.
• Working without UVs will allow you to use more polygons and get more detail out of your model. Whenever possible, delete your UVs from your ZBrush model. You can always reimport them at the end of the process.
• When rendering, ZBrush gives precedence to textures over polygon colors. This means that if a texture is active, then any polypainting you've done will not be visible. While painting, or to view your polypainting, ensure the selected texture is the Texture Off.

With this in mind, polypainting a model and producing a texture map is a simple process.

1. First, get a model. For this description, we'll assume that you don't need your UVs and can add them at the end of the process.
2. Set your subdivision level to 1.
3. Press Tool:Texture:Disable Uvs. This will delete your UVs. Make sure to have a back up OBJ file if you wish to use those UVs again.
4. Subdivide the mesh to get the number of polygons needed to match the map resolution you have in mind.
5. Paint the model, using alphas, masking, etc. Of course, you can sculpt at the same time you paint. Remember to turn on Tool:Texture:Colorize before starting to paint.

Painting With Your Sculpting Brushes

You can PolyPaint with the same tools you use to sculpt with:

• Alphas
• Strokes
• Masks

Simply enable PolyPainting by pressing Tool: Texture: Colorize and turn RGB on in the shelf. Once RGB is on you are ready to start painting!

Control the Shape of Your Brush with Alphas

You can control the shape of your sculpting by using an Alpha. To select an alpha you can do two things:

• Click the large Alpha thumbnail to the left of the canvas and choose an Alpha from the pop-up window.

or

• Open the Alpha Palette, click the large thumbnail of the Alpha and choose an Alpha from there.

To learn more about Alpha Controls visit the Alpha Palette page.

To learn more about Alphas visit the Alphas page.

Control Your Brush Stroke

ZBrush has several different Stroke types available for the artist. Each is useful for a different task. In the First Painting section we learned about the Colorized Spray stroke. For sculpting, the Dots stroke, Drag Rect and the Freehand stroke are very useful. Some of the strokes to the right are not visible while 3D sculpting. ZBrush's interface is context sensative. It will only show you the controls that you can use.

Using a Texture Map to Paint with in ZBrush

To PolyPaint with a texture map you must delete your UVs by pressing Tool: Texture: Disable UVs. If you have UVs ZBrush will display the texture map on your model instead of letting you use it to PolyPaint with.

You can create new uvs when you are done PolyPainting by pressing Tool: Texture: Auv. Make sure you are at the lowest subdivision level when you do this.

You can import your UVs again after you have finished painting by following these simple steps:

1. Press Tool: Morph Target: Store MT to store a Morph Target
2. Press Tool: Import to Import your OBJ with your Uvs made from outside of ZBrush
3. Press Tool: Morph Target: Switch to switch back to the previous geometry state. ZBrush will keep the changes you made to the UV but reverse any change the imported OBJ made to you model's geometry.

To enable PolyPainting with a texture map simply delete your UVs.

How Do I Work With A Texture Map in ZBrush?

PolyPainting works directly on the surface of your model.

The ZBrush approach for working with a texture map is as follows:

1. Bake texture map into PolyPainting
2. Paint using ZBrush's 3D sculpting and painting tools
3. Bake PolyPainting back to a texture map.

Note: If you want to paint on a texture map in ZBrush you must use Projection Master.

Baking a Texture Map to PolyPainting

1. Load the Model
2. Load the Texture
3. Divide the model so that its polygon count is close to your texture's pixel count. If you don't want to learn the math behind this just divide it as far as you can. If you want to learn the math, here is some info: a 2k texture map has 4 million pixels in it. Your UVs only use 70% or less of that space so the pixel count is close to 3 million.
4. Press Tool: Texture: Txr>Clr

You're done.

Baking PolyPainting into a Texture Map

1. Create a texture at the size you want for your final map. If its 2048 by 2048, follow the steps below:
   1. Set Texture: Width to 2048
   2. Set Texture: Height to 2048
   3. Press Texture New Texture
2. At this point the texture map will override your polypainting. Don't worry. Its still there.  :)
3. Do you have UVs? If yes, skip this step. If not, you have two options.
   1. Create UVs outside of ZBrush
      1. Set Tool: Geometry: SDiv to 1
      2. Export mesh by pressing Tool: Export.
      3. Layout UVs in your other application.
      4. Back in ZBrush, store a Morph Target by pressing Tool: Morph Target: Store MT.
      5. Set your model's SDiv level to 1.
      6. Import your model by pressing Tool: Import.
      7. If you have sculpted more since you laid out your UVs your mesh, at SDiv level 1, will be different. You will only want to import your UVs and not your mesh. To do this, simply restore the Morph Target, Tool: Morph Target: Switch.
   2. Create UVs inside of ZBrush
      1. Press Tool: Texture: GUV or Tool: Texture: AUV
4. Press Tool: Texture: Clr>Txr

Done!

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