Retoplogy over a decimated mesh

[tekgecko]

I am doing retoplogy over a mesh which has been decimated.

As usual I put subsurf before the shrinkwrap modifier for more detail. The only issue is, when I do this, it wants to snap to the bad topology of the decimated mesh. When I put it after the shrinkwrap it looks fine but obviously has less detial.

Is there any way around this?

Images here: https://imgur.com/a/0B8eF

[dinne7]

Uhm, I am not an expert but when I have retopologized something as exercise I have done it more manually than this. I have drawn the vertices with the magnet option, so that it projects my vertices right on the shape. For bigger area with no creases/details, I have used bigger regular surfaces like planes. And in the end I have merged all manually.
In the image, it isn’t trying, literally, to follow the bad topology, but it just follows the nearest points on the faces. When there are little details or creases it’s normal that it is gives this result.
So my suggestion is to retopologize it piece by piece, also because if you just put a sphere or a cube around it, it will be again a bad topology even if different because a good topology follows the flow of the mesh. Check some examples on Youtube to see what I mean. Just having parallel quads is not the right topology for a human (or not) face!
If you do it manually, and correctly, you can use subdivision surface modifier with success, after, and so avoiding to create too dense mesh with your own hands! Also, if you create a more similar shape around the model, using the shrinkwarp will be better. If you are interested on doing it, you’ve to create vertices enabling the magnet on the main toolbar and to select in its nearest menu the option “face” (so, where to snap the new vertices on the mesh). But before all see some examples on the web about the correct topology for a human.

If someone arrives with better answers, forget the mine.

[tekgecko]

Uhm, I am not an expert but when I have retopologized something as exercise I have done it more manually than this. I have drawn the vertices with the magnet option, so that it projects my vertices right on the shape. For bigger area with no creases/details, I have used bigger regular surfaces like planes. And in the end I have merged all manually.
In the image, it isn’t trying, literally, to follow the bad topology, but it just follows the nearest points on the faces. When there are little details or creases it’s normal that it is gives this result.
So my suggestion is to retopologize it piece by piece, also because if you just put a sphere or a cube around it, it will be again a bad topology even if different because a good topology follows the flow of the mesh. Check some examples on Youtube to see what I mean. Just having parallel quads is not the right topology for a human (or not) face!
If you do it manually, and correctly, you can use subdivision surface modifier with success, after, and so avoiding to create too dense mesh with your own hands! Also, if you create a more similar shape around the model, using the shrinkwarp will be better. If you are interested on doing it, you’ve to create vertices enabling the magnet on the main toolbar and to select in its nearest menu the option “face” (so, where to snap the new vertices on the mesh). But before all see some examples on the web about the correct topology for a human.

If someone arrives with better answers, forget the mine.

Hey thank you very much for your reply but this has been done manually as you suggested

[czerw]

Hi, try ‘project’ mode for shrinkwrap with negative and positive direction turned on.

[dudecon]

My approach is to use alternating modifiers. So, first subdiv, level 1. Then retopo to get the right shape. Then another subdiv, level 1 or 2 depending on how smooth you want it. Then start applying the modifiers from the bottom up and tweaking the geometry to get it just right.

[czerw]

Ok, if it works for you. If you still need help, would be easier if you’d upload your file.