How do you optimize Blender/mesh for sculpting with multiresolution modifier?

Question

When I sculpt using Multirezolution modifier I use the following tricks:

• I start with a base model which has 1000-5000 vertices
• For each subdivision level I try to finish all work which can be done there

• I only do fine details when I reach multimillion faces level

• If things are too slow -- I make a copy of my model, move it to different layer, apply Multires, sculpt, and then reapply my changes using 'Reshape' button of Multirez modifier

Can you advise on other settings to make Multirez perform faster?

I would like to clarify -- there are situations where Dyntopo is not a right choice: for example after you done with exploratory sculpting, went through retopology, created UV maps, and reintroduced details level lost during retopology.

Answer 1

Edit: This post was made when the referenced tools were still considered experimental and not a part of the official builds. Now these tools and more are available from official builds.

There is a new option for adding fine detail but it is not fully in trunk yet. You would have to grab the GSOC Paint build from Graphicall.org.

Psy-f's build has curve and line tools that work as precision stroke brushes. Maybe that definition is not exactly correct but it's close enough I think. They work in sculpt mode as well but this requires extra geometry which is going to slow you down.

The idea here is to attach a 32 bit texture map(currently available) to your models UV's and then use that as a bump map. As is, this will not create real geometry but instead will create the illusion of extra detail which can be baked as a normal map. This seems to me to be the ideal situation for smaller detail since anyone would be hard pressed to tell the difference between real displacement and normal maps when it comes to the small scale that you are hoping to work with. This technique will also dramatically decrease your render times and the possibility of your computer locking up.

If, however, you insist on using true displacement then you can use this bump map in combination with the displacement modifier at a later stage. This will allow you to work with a lower poly model during the sculpt/modelling process and then you can crank up the multi-res detail in combination with a displacement modifier when it's time to render.

Even still, without the most excellent curve and line tools you can still paint bump maps but it's much harder to get the precision that these new brush tools provide.

Answer 2

Try the new Dynamic Topology! From the wiki:

Dynamic topology is a new sculpting mode that subdivides the mesh as needed, whereas regular sculpting only affects the shape of a mesh. This makes it possible to sculpt complex shapes out of a simple mesh, rather than just adding details onto a modeled base mesh.

To start using Dynamic Topology, remove or apply your Multiresolution, then enter Sculpt Mode and select Enable Dynamic Topology under the Topology tab of the Sculpt toolbox.

This eliminates the need for Multiresolution, because the resolution is automatically adjusted as you sculpt. You can hit the Optimize button to optimize your mesh.

To adjust your resolution change the Detail Size (ShiftD). This is measured in pixels: any attempt to sculpt on surfaces with a lower vertex density than this pixel length will be subdivided. This means that you can very easily adjust this by zooming in or out, or manually with the Detail Size setting.

^source

Here's an example of using Grab (no dynamic topology) vs. Snake Hook (with dynamic topology):

I would highly recommend Kent Trammell's video series Creature Modeling for Production (USD $48), which uses dynamic topology, among many other tools.