In this tutorial I'm going to show you how to automatically retopologize any 3d model
using absolutely free software.
And to do this we're going to be using some software called instant meshes.
So if you do not already have it, go to your internet browser.
Type in instant meshes.
Go to the GitHub, that's the first thing that's going to pop up.
And then just scroll all the way down to pre-compiled binaries.
This is where you're going to download it.
You're going to either get windows, mac, or linux version.
And it's going to give you an executable.
So once you have that downloaded we're ready to go.
So in this case I have a demonstration model.
If we go to edit mode.
You can see that this thing has a lot of faces.
It has around 245 thousand faces.
Most of those, if not all of them, are triangles.
And also if you look at the face size it kind of varies.
So here they're kind of small and then in this area they're very big.
So we have three issues we want to get rid of.
So we want to take this high resolution, that means high polycount model and make a low
resolution, low polycount model that's primarily made out of quads.
So that's our goal.
So what we're going to do is we're going to take our model, in this case it's in blender.
File, export, and export it as an obj.
Instant meshes does not accept most files but it does accept obj.
So no FBX or anything like that.
So I'm going to export it as something called hires.obj.
And it's going to take a second because it has such a high polycount.
And this is one of the reasons we want a low resolution mesh.
Ok, so once that's done what we're going to do is open up instant meshes.
For me my executable is right here.
It's going to open up really quickly.
Make that fullscreen.
Click open mesh and then just navigate to wherever your mesh is.
For me that's right here.
So that is going to load in.
And then how do we navigate this 3d model?
Well, left click is going to be orbit, right click is going to be translate, and then middle
mouse scroll is going to be zoom in.
So left mouse, right mouse, and then scroll.
So this is how we navigate our 3d model.
The first thing we need to do is pick an algorithm for this retopology.
There are three and you want to stick with this default one unless you look at the documentation
for the advantages and disadvantages of these two.
So this one has been working fine for me.
Then what you want to do is define a target vertex count.
And this is saying how many faces do I want when we export this as a low resolution mesh.
So this is what it's going to aim for.
You don't want it too low because then you don't have enough polygons to work with.
If you make it too high then what was the point of making a low res version.
So I'm going to keep at 7.66 thousand, right, so we have 7600ish polygons as our target.
You can move this up or down.
And then once you're happy with that number, click solve right here.
And this is going to give you an orientation field which basically looks like a bunch of
lines.
And what we can do is we can actually edit this.
We can open up our comb tool, I think that's what they call it, I'm not sure.
Basically you click this and you can redefine how you want these lines to be displayed.
So for example if I make a circle around here, it's going to recalculate.
And you can see how its actually considered my brush strokes.
So I'm going to deselect this and basically what this orientation field defines is what
the edge flow is going to look like in your low resolution model.
So when I made a circle right here I basically said in my low resolution model I want a polyloop
here.
So I want a polygon loop over here.
And we can navigate over here for example, open this up again, and then add another one
like this.
It's going to recalculate and consider this.
We can want our edge flow going like this along here etc.
You can spend a lot of time doing this.
But then once you're happy with that what you want to do is go to your position field
and click solve.
And then you see we get something that pretty much looks like a wireframe of what our low
resolution mesh might look like.
Again you can do something very similar, you take now the brush tool and then you do a
very similar procedure.
And you see it kept our strokes from before over there.
And then it's recalculating we'll do another here.
And you can see how this updates very quickly.
So this tool is very powerful.
So we're going to disable this and then when you're happy with that what you want to do
is click export mesh.
Now what we want as I stated is a pure quad mesh.
We want dominant quad topology.
So when we do this what it's going to do is it's most likely going to increase the polycount.
Because before it can actually put triangles and that will let it end loops.
But we want mainly quads so it's actually going to bump the polycount but that's fine.
We're going to move this smoothing iteration, this is how much it's going to smooth it out
after it calculates.
So we're going to move this up to, not to five, but to one.
And then click extract mesh.
And you see like I said this wireframe looks a bit denser than what we had before but this
is still pretty good.
And it does a fairly good job, of course we have a couple weird areas where you see these
weird quads.
But this is where a triangle most likely would have been before.
Like right here we have a star, I think that's what it's called.
Either way, we now have a low res mesh.
What you can do is you can tweak these values and do this again.
But let's say that we're happy with it.
So click save and then we're going to call this one lowres and then in this case .obj.
It's going to export.
And now we can close this.
Go back to blender and now we're going to import.
So file, import, and then obj.
And then import low res.
And let's actually compare the two.
So I'm going to move this to the side.
Like that.
Ok, so now you see that we have our high res right here and our low res.
Although, our low res is looking very choppy.
And normally what you do is you enable some shade smooth.
But you see that nothing happened.
That's because if you go into edit mode you're going to see that all these edges are marked
as sharp.
To disable this select all your edges and go to edge and then clear sharp.
And then you see when we go back to object mode everything is looking nice and smooth.
So in this case you can't really tell a difference and let's see how much we dipped our polygon
count.
So in here we had 245 thousand, and then in here we have around 31 thousand.
So that's pretty good, we could have even lowered it more when we were defining our
target vertex count.
And then if you have much more detail here we can always bake down our high res into
our low res and save that data in a normal map.
But that's pretty much how to do it.
If you want you can always, once you're here you can always do some fixes by hand.
I'm not going to do it but it's totally possible.
So either way get instant meshes, it's a very amazing tool for what it is.
It's free, it let's you define your orientation field and all this.
Hopefully this tutorial helped you, again make sure that you're using obj.
I hope you learned something and thank you for watching.