3d Tutorial: Using ZBrush and ZRemesher to ‘retopologise’ a high poly model
Last week I looked at Topogun, a cool little program costing about $100 for allowing you to re-topologise a high density Zbrush model for use in 3d Studio Max, game engines or whatever.
Today I learned about the new ZRemesher tools in ZBrush version 4R6, which can with the click of a button reduce the poly count of your model to a workable figure.
The primary use of ZRemesher is to lower your poly count and to reorder the polys of your sculpt as they become distorted during the sculpting process. It is not primarily a retopologising tool in the sense of making animation quality models, but with a little preparation it can be used effectively on simple models to produce the edge flow necessary for animation.
This has the advantage over Topogun in that it is pretty much instantaneous, whereas Topogun you could spend several hours manually re-topologising.
Topogun on the other hand still has the advantage in that you have complete control over the edge flow of your new mesh. ZRemesher can produce some imperfect areas, especially if you have complicated mechanical details etc.
1. With your high poly model workable in Edit mode, Open the Geometry tab in Zbrush. Click on the ZRemesher Sub-tab.
2. If you want, you can literally just click on the grey Zremesher button and it will run through the process, however it is worth looking at some of the settings available first.
Alt Click: By Alt-Clicking the Zremesher button, you can use a different remeshing algorithm. The results will be pretty much the same but you may find one or the other just slightly better.
Poly Count: With this slider you can set your target poly count of the remeshed model. You can quickly undo and reset the slider to tweak your results. The number by the slider is effectively how many ‘thousand’ polys to aim for.
Adapt: With Adapt selected, ZRemesher will allow itself to deviate slightly from your target poly count, in order to stick a little bit closer to the complexities in the original model – wrinkles, folds etc. It will also adjust the sizing of polys in areas that need a bit more density and detail.
Adaptive Size: The adaptive size slider affects the size variation in the newly created polys. At the default 50, tighter curved areas- wrinkles etc will have smaller polys allowing more details to be saved. Setting it down to near zero will keep all polys basically the same size, therefore much subtle detail will be lost, resulting in a soft, blobby look.
ZRemesher Guide Brush; In your palette is a brush which will allow you to paint guideline lines on the surface of your sculpt, which will then influence the edgeloops created by the Zremesher algorithm. This is useful for when the algorithm on its own isn’t creating perfectly clean edge loops around targets such as eyes, mouths and noses. This is influenced by the Curves Strength slider, which affects how much of a bearing these guidelines have. This is the tool you will need to make use of to create edgeloops suited to animation.
In the Images above you can see the effects of the ZRemesher. The top image clocks in at around 86,000 polys, whilst the bottom is around 8,000 with the poly slider option set near the left. You can also see how the remesher has created nice smooth edge loops around the model.
From this point you can then export your model to 3DS Max or Topogun etc for any further refinements before putting it to use in your project.
To speed up the process if it is going slow, use Decimation master to reduce the poly count of your sculpt, then use ZRemesher to create the required edgeflow.
ZRemesher can be used a second time – this can give you better edgeflow than teh first pass whilst maintaining the same polycount.