Retopology for newbies

[Time.Bandit]

Hello all. I have been seeing that people sculpt something, then retopologize the model. I do not understand the reason and process in which it is done. Can someone point me to a tutorial that explains the reason and process? I have not sculpted anything yet. I plan to import future models I make in Modo in order to add details via sculpting, and want to know if retopology is needed for that?

 

Thanks

[Tony Nemo]

Retopology is necessary when you have sculpted an object. Imported models have their own topology. If the "added details" are substantial they may require retopology (import your original UV mesh and make adjustments) but the added details will need to be baked in the Retopo room for the changes you have made to appear on the normal or displacement maps.

[Hugues]

I was asking a similar question and got an answer here:

http://3d-coat.com/forum/index.php?showtopic=17862&p=124289

[L'Ancien Regime]

There's lots of reasons for retopo and some of them are changing with technology.

 

It used to be that you had to cut down on polys for the benefit of the render engine, but with some of the new render engines like  Clarisse retopo almost becomes superfluous; you can render billions of polygons in a matter of  1 to 5 minutes with  Clarisse.

 

The other is for animation; you need to create a rig, attach the skin of your model to the skeletal rig which is essentially a deformer and then paint weights on the attachments so that the  skin will deform according to the structure you desire.

 

This demands a very specific kind of topology that through over a decade of experience animators have evolved for dealing with the exigencies of rigging deformers and anatomy.

[TimmyZDesign]

There are two reasons why retopology is necessary:

1) To reduce the polygon count of an object.

3D animation software must calculate the location of every polygon for each frame of an animation. If there are too many polygons, the computer will slow down and animation will take too long to create and it will take too long to render. Therefore you can create a simpler version of your animated object by retopologizing it. This simpler version will be easier to animate and render.

Also, if you have sculpted an object with a high polygon count (in order to create lots of detail), then that object will not animate well. You can transfer the details of the high poly count object to a low poly count version of the object by using normal maps, bump maps, or displacement maps. First you would retopologize your high poly object (so that it is then a low poly object), and then you use a "map baker" to create maps of the high poly object. You then apply the maps to the low poly object, and the high poly details are retained, but the object stays low poly. The end result is that you can easily animate your low poly object, but it still looks like a high poly object.

2)To improve the polygon topology of your object.

Especially for animated characters, it is necessary to have an ideal topological flow. The edge rings of the polygons should follow the curvature of your character in a specific way so that the character will deform properly when animated. Bad topology will produce unwanted deformations when animating. Therefore you can create an ideal topological flow on your character by retopologizing it. There are many tutorials available on YouTube which show you how to create good topology for animated characters. Here are some examples:

http://youtu.be/im9XZf2C1s0

http://youtu.be/a_2hN0_zHvA

http://youtu.be/V8V94aBOb4g

[SPACEY]

I'm having trouble finding info on how to make uvs from the auto mesh.

[arumiat]

I'm having trouble finding info on how to make uvs from the auto mesh.

 

What sort of UVs are you wanting? You can automap the auto retopologised mesh which will create UV seams & unwrap the mesh. This may be suitable depending on what you need to use the model for.