Blender Remesh Error in Sculpt mode. How do I decrease the polygons correctly and save the project?

Question

I have a big problem. Some time ago I asked a question about this project regarding the selection of polygons to be able to work in zones. The problem now is another, not being an expert in polygonal sculpture, I immediately started creating my character at the maximum polygon resolution. For this reason now the file weighs too much and when I open it despite having a PC worthy of power, the 500k vertices and 900k faces I would say are really excessive. In fact, every action that I go to perform in blender, whatever it is, needs time to load it.

In the previous question, I received an answer that my project had too many polygons and was advised to remesh my character, thus creating a low poly copy.

However, after some time I just tried to perform the remesh, perhaps inserting wrong values, I don't know, even if I took reference from the screenshot that was recommended to me. Performing the remesh I encountered these problem.

Problems :

1. The whole surface is pierced, and my mesh is corrupted as shown in the figure.
2. even the color used with vertex paint is canceled and transformed into a totally reflective surface.

Principal Questions:

1. Am I still in time to be able to recover this project or is it to be thrown away and redone from scratch?
2. How can I consistently decrease the weight of my file without completely ruining the character?
3. Why does remesh create these holes? Can it be caused by vertex paint? How do I resolve? (I also tried using the Decimate modifier too, but I think it's not the exact tool).

Extra questions:

1. What would be the right technique to create a character, what are the precautions to use, especially not to stumble into certain errors.
2. Above all what are the steps that should be followed for the complete realization of a character? Such as creating a low poly copy, how to color in the right way, but above all when to do one thing instead of another. For these two points it is clear that a simple answer is not enough, so if you know where to send me to document me I would be grateful. (A site, a guide relating only to this). Or even some simple basic concepts that make me understand the steps to be respected.

p.s. After completing my application I was able to find several questions already asked, related to some of my extra doubts, so if you agree I will not delete these questions as maybe they can be used by someone who is looking for the same things and cannot find them. However, I have found several interesting answers for these extra questions of mine, which I will attach the links to my question. while obviously higher priority will have to be given to questions concerning my project. However, opinions, reflections and advice are always welcome. For example this question, yes, can answer some of my doubts and I also found a video on how to paint in layers. Paint high-poly mesh and then bake for low-poly, OR just paint low-poly with normal-map applied? But I think I need a specific answer to this question because I can't work on this project anymore. I want to resolve my fault.

While that other question has managed to answer some of the polygon sculpture questions about how it's best and what it's best to sculpt a certain way for. What is the importance of low poly vs high poly?

-I tried to upload the file but it weighs 90mb, and the maximum is 30mb. how do i compress the file to upload it through the exchange? or should I use something else?

[ https://drive.google.com/file/d/1Idc8Jg9wtHwQey5V7qpwuxwtw1QjEM4K/view?usp=sharing ]

Thanks in advance.

Answer 1

First of, sorry I couldn't replicate that crazy error. It happened to me once, also with a very complex mesh, but I was using a much weaker laptop and I didn't optimize the mesh before remeshing, so maybe that was it.

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Now, there's still some hope for your character, but you will come out of this having learned a few valuable lessons.

The very first thing you have to do is Decimate the mesh to make it manageable. Pick the Collapse option and you can go down to 0.2 with absolutely NO loss of detail, and you can probably push it even lower.

You'll lose a ridiculous amount of polygons and make blender happy!

(By the way, it's not necessarily your computer that can't handle the pressure, it's blender that isn't exactly optimized to deal with so many polygons)

Now that you can breathe easier and your vertex paint is still there, it's time to think about the future and weight your options.

Question: Are you going to animate this? Do you need this mesh to be posed with bones? If yes, keep reading. If you just want to make it prettier and render a still frame, never mind, you can stop, you're all set.

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Animation works best with as few polygons as possible, and those polygons should have nice symmetrical "flow" to make it smoother and easier overall. That's why we need to remesh.

But Blender's Remesh options (all 3 of them, Quad, Voxel and good old Smooth) are, I'm sad to say it, rubbish...

• Quad refuses to work with non-manifold meshes (you have to go around hunting down non-manifold areas in edit mode). It produces OK flow (if it feels like it), but is slow and non adaptive, so it'll make many polygons where you could do with fewer, and not enough where you really need them.

• Voxel can be adaptive so it doesn't make too many polygons where they're not needed but flow is just not there, and to reach high detail you end up with more than you started with. But at least it can get reasonably close to the original!

• Smooth is outright insane, it'll choke itself to death to achieve even minimal detail and STILL somehow manage to ruin finer things like earlobes. Just, no.

Oh yeah, and they'll all kill your vertex paint! In fact, best kiss that one goodbye anyway, it's doomed no matter what your next step is. Sorry about that.

So that leaves you with only one sane option....

Retopology. Basically, create a new mesh, snap it to the old one for reference, extrude new edges, fill it with the least number of polygons you can afford, then throw away the old mesh. There are many retopology tutorials and even a few addons that are supposed to help you (eh, not really). It's a drag - it takes a lot of time and is indescribably boring, but the result will be a clean, symmetrical mesh that retains all the detail exactly where you need it, and not one vertex more.

When you're done you can vertex or texture paint to your heart's content, knowing that you have a mesh that can do ANYTHING you want it to.

This is my (and many people's) workflow:

• Sculpt. Go crazy, add as much detail as you want.
• Downsize it with Decimate.
• Retopologise.
• Unwrap, UV, rig, animate.

Answer 2

I just wanted to add that I encountered the same choppy model result from remeshing and that closing up all holes in the model solved the problem.

This was the result using Remesh when I had forgotten to close the neck hole:

After closing up the neck hole the Remesh worked fine:

Happy Blending!