ebookslogoboss

[ #3DCoat #zbrush #sculpt #Software #retopology #news ]Metin Seven a 3D designer, illustrator and animator has done a comparative study on the two best 3D auto-retopology algorithms available today — 3D Coat's Autopo and ZBrush's ZRemesher. We bring to you in the following section some of his work.

>> See Also: 3D-Coat V4.8

I love the technique of freeform digital sculpting, as an alternative to polygon subdivision modeling. The workflow of digital sculpting feels very much like traditional sculpting, adding daubs of digital clay and dynamically shaping them into a sculpture, while polygon subdivision modeling requires careful construction and adjustment of a quadrangular polygon cage in order to successfully subdivide it to a smooth result. This quad-polygon structuring and restructuring can be time-consuming and sometimes frustrating, and often takes away the spontaneous part of 3D model creation.
A downside of freeform digital sculpting is that it usually results in a messy polygon structure, making the 3D model unsuitable for deformation, such as for posing or animating a character. But even if no posing or animation is required, the semi-random polygon structure often causes visible surface irregularities, especially if you sculpt with triangular polygons, like when using Blender 3D's Dyntopo sculpting. Dyntopo is short for dynamic topology, and I love to use it for conceptual sculpting, as polygons are generated in realtime while you sculpt, enabling you to freely focus on shaping your model without having to worry about its polygon structure.
Triangles and quadrangles
A smooth 3D surface impression can be achieved by either a smoothly flowing quadrangular polygon structure or a high polygon count (or both). A smooth polygon flow is usually realized by constructing rows and columns (rings and loops) of quadrangular polygons that fluidly follow the flow of the 3D shapes (convex and concave areas, creases and other surface features).
For the best of both worlds, many 3D modelers manually retopologize their models when the freeform sculpting is finished, restructuring the surface to a smooth quad-polygon result. But manual retopology still requires careful planning and patience as you place the quads across your sculpted surface. It can be a tedious, time-consuming and sometimes puzzling process.
Automatic retopology tools
At the time I write this, the most popular 3D sculpting tools are Blender 3D, Pilgway's 3D-Coat, and Pixologic's ZBrush. To ease the process of retopology, 3D-Coat and ZBrush offer a way to automatically generate a nicely flowing all-quad surface for your sculpture. 3D-Coat's auto-retopology tool is called Autopo, and ZBrush features ZRemesher.
There is another automatic retopology tool. It's called Instant Meshes, and deserves an honourable mention. Instant Meshes is fast and free, but did not make it into this test, because it generates too many triangular dead-ends amidst the resulting quad-polygons, resulting in visible artifacts after subdivision. The Instant Meshes quad-retopology algorithm or a variation is used by The Foundry's Modo.
Blender 3D does not yet include an automatic quad-retopology function, only a generic, voxel-based quad-poly projection method in the shape of the Remesh modifier, which doesn't orient the polygon flow to the surface features.
3D-Coat Autopo versus ZBrush ZRemesher
After speed-sculpting the above-pictured happy dog I decided to do a little test to get an impression which auto-retopology tool yields the most satisfactory result, 3D-Coat's Autopo or ZBrush's ZRemesher.
I used 3D-Coat version 4.8, and ZBrush 4R8. Symmetry was activated in both tools, and no changes were made to the default settings, with two exceptions:
1 — ZRemesher's Adaptive option was deactivated, to force the resulting polygon amount more to the Target Polygons Count value.
2 — Autopo's Required Polygon Count was doubled from 5000 to 10000, because that made the resulting polygon amount comparable to a ZRemesher Target Polygon Count value of 5, which should equal 5000 polygons, but the resulting amount of polygons still deviated somewhat from that number.
ZRemesher offers two different auto-retopology algorithms. You can apply the alternative method by holding the Alt key while activating ZRemesher.
The Autopo algorithm and ZRemesher's algorithms take a similar amount of calculation time, depending on your computing capacity and the model's complexity. Usually the calculation takes less than 30 seconds for a model of average complexity, up to a few minutes for a more complex model...
Click here to access the remaining part of the study, and most importantly, his final notes and advice.
More about 3D Coat [post_ads_2]