Retopologizing multiple Meshes

ILoveArt

Hey Guys,

So I'm new to the forum and I've got probably a silly/dumb question that I'm hoping can be answered. I have blocked out a small Air Conditioner in Maya with multiple meshes and not as a contiguous mesh and intend to bring all the meshes into Zbrush and add tons of detail to it.

Obviously they will come in as separate subtools but my question is, can I possibly merge all the subtools after I'm done detailing them in Zbrush then bring them into Maya and retopo it as one low poly contiguous mesh to bake the high res onto it after the low poly is UVed? I haven't really seen any tutorial online talk about multiple meshes being retopoed into 1 continuous mesh, I just wish to know if it's possible and there's any tutorials out there or anyone can kind of summarize how one would do it properly. Thanks guys! I've provided an image of my model so far in Maya that I intend to bring into Zbrush!

ILoveArt

For Istance:



He had multiple meshes for his high poly and his low poly is pretty simple but still gets out all that detail, unfortunately he did not explain his process.

Bartalon

That's usually what I do. I'll make a copy of my ZBrush model, merge it all together and decimate it so I can take it back into Maya for retopo/UVs.

Sometimes if I know the shape won't change at all from sculping (in cases where I'm only adding superficial details like scrapes, dents, surface texture, etc.) I will retopo before I go into ZBrush.

ILoveArt

Right on Bartalon, I really appreciate your input and clarifying the workflow. I guess one of my main concerns is, when the model is extruded inwards but also has the metal grate that's in front of the fan, Would you recommend retopoing the body with the inward extrusion separately from the metal grate and fans ? or completely retopo over the grate and inward extrusion and fan between them and expect the normal to bake out the inward extrusion/fans/grate proper parallax? I've put up a picture to clarify the section I'm referring too. Thanks so much!

Bartalon

Depends on the importance of this particular model. If it's doomed to be a background prop then you might be able to get away with baking the inset, fan blades, and the circular pieces of the grill into the texture. Assuming this is a portfolio piece and it will be right up in the viewer's face you might want to have all that stuff modeled out.

You can always cut those details out in your LODs also, if you need to make them.

Noors

Just model a box, and be sure while baking that your cage envelope the HP entirely. In the example you posted, there's no trick. It's a frontal projection, there's no parallax. Now of course if you want the fan spinning, it's an other story.

ILoveArt

Right on, very solid responses Bartalon and Noors. I really appreciate you both taking the time sharing your thoughts. It's certainly supposed to be a portfolio piece so I may end up modeling the fan and dip behind the fan and the grate separate but I certainly see your point Noors with the example provided, I tested a bake out but it just didn't give as much depth as I would have hoped in the fan section. I could probably equal out the depth sacrifice with good mapping like he did, but I think for now I'll go with more than just box modeling. Really thanks for the input ya'll! Helping me skip mistakes!

Noors

Yeah, well, AO, bit of lighting, could help to give a better deepness feeling over the normal map alone. In the example, i would have put a bit of grid shadow on the fan for instance.
Still, depends of what you want to achieve. Also i'm not sure a more detailed model is better for a portfolio. Models are still pretty higly optimized in games, so you might want to show that you can also do it.

sprunghunt

For something this simple I wouldn't even bother merging the subtools together. I'd just make a new lowpoly over the top of the existing hipoly. It's a box with a few extra details. It's not a lot of work to match the hipoly's shape.

Usually for retopologising I'll ignore the smaller meshes in the hipoly and I'll only use the hipoly mesh as a basis when it's a complicated shape that's hard to match exactly.

ILoveArt

Gotchya, this all starting to make sense for sure. I've got one other question I guess, as far as the low poly goes, how close does the shell of the low poly need to be of the high poly for the projection to work well? For instance, my high poly has curved/softened edges, would I have my low poly mirror that curvature value or should it be just hard edged and cover the soft high holy edges?

heyeye

A different approach would be to separate just the grate in front of the fan and bake that separately on a beveled plane. The bevel will help sell some of the depth and it's a cheap way to allow the object to have a little more radius before the normal map is no longer believable.

This thread - http://www.polycount.com/forum/showthread.php?t=105551

Has a lot of great examples of how powerful baked normals on alpha cards can be used. Cheap and really helps take the box silhouette into something more interesting.

ILoveArt

That actually will save me time and pretty awesome. I forgot all about alphas lol. Makes sense. I was having trouble modeling the low poly to overlap the high poly correctly with the grate going further out then the rest of the front of the air conditioner. With your suggestion, here's what I got so far for modeling a low poly version for the main body of my AC. I hope I'm doing it right and it projects well after I UV it. I didn't model in the foot pegs or fix the ngons yet but I'm doing that now so ignore those. Just want too know if this is good or not.

ILoveArt

Is beveling your low poly model to round it out bad? I test baked my high to low and it got this weird distortion/split where the bevel is and where the side of the grate is supposed to be straight.

heyeye

Best way to see if it bakes is to bake it. Objects like this wont take very long to calculate so fail as much as you need, it'll be quick.

If you want nitpicks, A lot of your loops on your low poly can be tri'd off instead of having them go around the entire object. Best rule of thumb is if it's not adding to the silhouette, it can usually be deleted/welded to a corner.

Also if you're new to high/low bake downs, there's a lot of really good stuff on the PC wiki. Hard/Soft edge workflow, xnormal cage stuff, support loops to avoid normal map skewing, etc..

Lot to learn, best thing to do is when you see a problem, look it up on the wiki because i guarantee someone else has already done the obstacle course of trial and error for you and found the best solution.

Noors

You 're not baking with an averaged cage, hence you have this clone stuff on the side. I don't know the process in Maya tho. But yeah look at the wiki. Maya isn't the best tool to bake normals aswell.
Also from what i guess, this extrude on the front is way to big. You should match the hp surface as close as possible. It can intersect the high.

ILoveArt

Thanks for the input noors! Yea I tend to do projection in Zbrush to bake out my normal and it works well, however my computer no longer puts up with my high poly count even when decimated so I'm forced to bake in maya for the time being, definitely not the best. I looked at xNormals and will probablygive that a go after I redo my cage. I finished my high poly already so it's down to this supposedly simple retopo step! ARGghh! I think I'm just overthinking it.

CheeseOnToast

Maya actually bakes normal maps very well. I don't know why people keep saying otherwise. That said, Xnormal is faster and can bake out a bunch of other useful maps at the same time.

Noors

I just dont know with what engine Maya is synced. I could say max rtt is good enough too, but it's synced with nothing.