MicroMesh

From ZBrush Info

MicroMesh is a BPR render feature which allows you to replace a FiberMesh object’s fibers or the individual polygons of an object with another 3D model. In other words, a model’s Fibers or separate polygons are rendered as if they were actually instances of the selected 3D model.

This solution is a great way to create rich renders with more details very quickly and easily. For example, you could put individual feathers on a bird or scales on a lizard.

About MicroMesh

MicroMesh replaces a predefined PolyMesh3D model at render time through the BPR render. The predefined PolyMesh3D will replace all single polygons with itself when a BPR render is executed. To do this you need to select a model to use as your MicroMesh by clicking Tool >> Display Properties >> Select MicroMesh.

The MicroMesh selector, located in the Tool >> Display Properties sub-palette.

As soon as the MicroMesh is selected, a preview will appear on each polygon of your current SubTool. This MicroMesh will replace all polygons at render time. The preview will allow you to have an idea of how your MicroMesh will render before doing your BPR render.

The orientation of the MicroMesh is defined by the pivot point position and orientation defined for the inserted model in the Tool >> Preview sub-palette. The size and orientation relative to the support surface are then modulated by the support mesh polygon size and orientation.

• Use the Tool palette to select the model that will be inserted as a MicroMesh.
• Use the Tool >> Preview to set the model’s pivot point and orientation.
• Use the Tool palette to select the model that will receive the MicroMesh.
• Use Tool >> Display Properties >> Select MicroMesh to choose the model from step 1.

To get an understanding of how your MicroMesh will be viewed relative to a polygon we recommend temporarily appending the Plane3D to your defined MicroMesh in Step 1 above. Use this to evaluate if the MicroMesh will be clipped by any one polygon. You can then delete the Plane3D SubTool so that you’re ready to move to step 2.

The MicroMesh feature will replace every polygon of any standard mesh. However, when using MicroMesh with a FiberMesh object, the MicroMesh will be stretched along the individual fiber regardless of the number of segments that are in each fiber.

To protect portions of your model from the MicroMesh you will need to split the object into separate SubTools.

To instruct BPR to render your MicroMesh you must enable the Draw SubMesh option, located in the Render >> Render Properties sub-palette.

Note: MicroMesh can’t be generated as real geometry. It is only visible at render time through BPR. This is because the total polygon count from converting a MicroMesh into actual geometry would very easily exceed what ZBrush or your computer is capable of handling.

Millions of Polygons

It is important to keep in mind that a MicroMesh can be instanced hundreds or thousands of times on your surface. Depending on the polycount of the support mesh and the number of polygons in the MicroMesh, rendering can take some time. For example, if you apply a MicroMesh with just 1,000 polygons on a FiberMesh containing only 10,000 fibers the rendered result will be 10 million polygons! Be mindful of this as is quite easy to reach billons of polygons at render time when using the MicroMesh feature!

On a non-FiberMesh, as mentioned above, an instance of the MicroMesh will replace every single polygon in the selected mesh. If you load the default Cube project, the base mesh is already 24,500 polygons. That means that a MicroMesh would be applied to the cube is 24,500. Multiply this by the number of polygons in the selected MicroMesh to determine the final number of polygons ZBrush will need to render. In this case, that same MicroMesh with just 1,000 polygons would result in a render of over 24 million polygons.

MicroMesh Workflow

The first step before using the MicroMesh is to have two 3D objects: the MicroMesh itself, and the mesh which will be replaced by the MicroMesh. Both items must be PolyMesh 3D objects. (You cannot use parametric objects, DynaMesh, ZSpheres or other object generators as a MicroMesh, although you can convert such objects to PolyMesh 3D and then use them as a MicroMesh.)

Note: ZBrush will automatically convert a Primitive 3D to a Polymesh3D when selected as the MicroMesh.

The MicroMesh support object can be a single model or one of its SubTools. Several SubTools can have the a MicroMesh however, the MicroMesh itself cannot have multiple SubTools. If you wish to use a model with multiple SubTools as a MicroMesh you will need to first merge its SubTools.

Select the support SubTool which will have its polygons replaced by a MicroMesh at render time.

Go to Tool >> Display Properties and click on the Select MicroMesh button. A selection window will appear, allowing you to select the 3D object that will become the MicroMesh.

ZBrush displays a preview of the MicroMesh on the selected SubTool. This allows you to evaluate if any changes need to be made to the MicroMesh (such as proportion or shape) so that it will fit the result you are looking for.

Before rendering, you must enable the MicroMesh feature by activating the Render >> Render Properties >> Draw SubMesh option.

Do your BPR render by clicking the Render >> BPR Render button or using the Shift+R hotkey.

When render computation is complete, your support mesh will be replaced by the FiberMesh model.

Note: The MicroMesh model can be saved in the ZBrush Project (ZPR) or the ZTool (ZTL) file.

In the left image you can see that any polygon can be substituted with another mesh (MicroMesh). The image on the right shows how you can use FiberMesh with a MicroMesh and how the MicroMesh is then stretched along the individual fibers.

On the left, the support mesh for the MicroMesh, where all polygons will be replaced by the selected model (shown in the middle). The figure on the right shows the resulting render with the duplicated model.