Retopology: What Do I Do?

ChrisLambert

Hello all,

So I have this sculpt:


And I need to now make a low poly version and I'm trying to figure out the best process for this.
First I decimated the mesh as low as I could (if that's the right thing to do?)



I keep some extra polys around the complex areas.
Then I heard the best thing to do was to use ReMesher so you can get back relatively even quads.

But this happens...



And I have no idea what to do...
I've tried lots of different settings but every time the padlock areas mess up, and the brackets tend to melt into the box.

Do you have any ideas how I could get around this issue? I've been scratching my head for days, and I might be confusing myself with all the different tutorials I've watched - all with different techniques...

Thanks in advance for any help!

jRocket

Most of the time, the auto-retopo isn't very good. I recommend manually retopologizing your model, but zbrush isn't very good for that.

poopipe

If you really can't be bothered doing it all by hand (and why should you?) then taking the decimated mesh into a proper modelling package and cleaning it up should yield a pretty decent result in a reasonable amount of time. 

ChrisLambert

Yeah, I've been having a go at retopo in Blender, but was just wondering if there are better ways to go about it - seems like there are a lot! I feel like ReMesher can do it but I maybe need to use Polypaint... or just find a way to stop it destroying those areas... I just can't seem to figure that out haha.

Alex_J

Unless you plan to make a career out of making static props only, you'll have to learn how to manually retopo and create clean, deformable topology.

ChrisLambert

Absolutely! I'm just trying to find out all the options
That way I'll hopefully be able to decide what is best for each piece - not that I'd want anything to have terrible topology!

Alex_J

I'm by no means as expert, especially wiht enviro/prop related things, but my inclination would still be to manually retopo this item (although I would have built the game model first anyway). Reason being : 

1. it's very simple. Just a rectangle with some other rectangles. Lock will be a litlte challenging but nothing crazy. 

2. By using clean topology for things like the metal brackets, you can easily mask these pieces during texturing. 

3. You can easily unwrap and make straight, uniform UV's.

Whatever works for your situation, though. Certainly no harm in getting familiar wiht decimation master and zremesher. They are tools you will use a lot.

sprunghunt

You can use zremesher for parts of the model - like the wooden bits - and then use manual retopo for the other bits. 

kanga

You havent actually said what you want to do with the model in the end, and what the model has to do. Does it have to open, is it to be used in a game engine, do you want to bake textures with it, and if so what software will you use to texture it? All this helps give you the answers you need.

ChrisLambert

@BIGTIMEMASTER I had built the game model first but unfortunately it was very bad and gave bad bakes so that's why I'm having to redo it - hopefully with a better result!

@sprunghunt I was thinking this could be a good idea... but I still feel like I might be missing something in the options of the ReMesher... I'm trying to look into Polypainting, or using the brush that you can set topo lines. Maybe that would help with the hard edges?

@kanga It's a static game object for a scene in UE4 (non animated). I'm texturing with Painter, and baking textures with any software that gives the best results (XNormal, SP, SD, Blender).

kanga

Ah ok. Right. This is what I am doing for the first time using Blender (with a character that has some mechanical parts like a shovel).

Blender, ZB and SP is all you really need. This is what I do:

Forget remesher, it shines when you want to up your detail of the main sculpt.

-Separate the chest from the lock. Clown paint the two items (with polypaint) for use as masks in SP. Name them appropriately for import as selection sets in SP (you can find this on youtube). Export the hipolys to a disk. I like the fbx format.
-Decimate copies of the 2 highpolys. Decimate them low enough so they will work snappily in Blender, but not too low so you loose detail. Decimating in stages usually works best: 10%, 5%, 2% and 1% if the mesh will support it.
-GoB the Decimated meshes to Blender making sure the scale in Blender is good.
-Retopo the decimated meshes in Blender. For the lock you can just model over the form as snapping in Blender can get fiddly, and for mech objects this usually works quicker and cleaner.
-Uv the retopo meshes.
-Assign one smoothing group to the polys of each mesh.
Assign materials to each mesh (Im not sure if this is applicable to Blender but it is in Max, so again a quick google).
-GoB the meshes back to ZB and name them per the SP naming convention. Export them to a disk and the reason I send them back into ZB is that the fbx plug works well with SP.
-Import the lowpolys into SP and point them to the location on the disk of the highpolys you exported them to.
-Leave the number and type of maps specified in the SP baker, you will pretty much need all of them.
-Hit bake.
-Use the generated color map for masking in SP. The PBR workflow in SP will knock yr eyes out of their sockets!

Cheers.

ChrisLambert

Thank you so much for the response!

Think I have an idea how to move forward now. This is my first asset so I really am just learning as I go haha.
It's killing me because all I want to do is get stuck in to Painter, it looks so damn cool! But I can't afford to rush all the important stuff beforehand.

Thanks again!

kanga

Above is just a general outline and its the way I do it. You can use the web or these forums if you hit a block. Different folks use varied approaches but this one will work fine. And really SP, ZB and Blender is an awesome combo!

ChrisLambert

Yeah I've found tons of different approaches, so just finding the right one for this asset was the challenge. Every software seems to have their own little shortcuts tucked away, it's finding them which has been stumping me haha.

goekbenjamin

a little offtopic here:
ChrisLambert please edit the title in something meaningfull so maybe more people know at first glance if they can help or not?

FourtyNights

My advice with this chest is to model the clean high poly of this first by also adding some edgeloops to help maintaining quad distribution even, and bring it to ZBrush for detailing.

Then you can optimize your unsubdivided high poly cage mesh to a low poly. Keep in mind with detailing that don't break the silhouette of the high poly too much when detailing in ZBrush, to keep it matching with the low poly.

Our member, Alec Moody has a good workflow for this too:

https://www.artstation.com/artwork/Vy5J5

ChrisLambert

That's a great plan. Figuring out the best workflow from start to finish can be quite a challenge when starting out haha.