[Modular Character] Is there any solution to reuse armor over a range of body size?
polycounter lvl 6
Hi all,
I know this sounds like tech art fantasy, but do you know of any games that manage to fit a single armor (let's say a chest-plate) into different body size?
One of our lead artist mentioned doing this: imagine you have characters goes from young to old, and their body proportion varies between 6-head to 8-head, and somehow we will like to make a chest-plate for an average 7-head base mesh, and use some magic to make it fit on all bodies.
Is it possible? Has it been done?
Most modular character system assume consistent body size, I just can't recall a game that looks semi-realistic and can somehow still avoid making armors for different body size.
If you have got any tips, let me know!
EDIT: And by the way this is not for background characters (aka random crowd), but rather the main character and key NPC, to enable player customization.
I know this sounds like tech art fantasy, but do you know of any games that manage to fit a single armor (let's say a chest-plate) into different body size?
One of our lead artist mentioned doing this: imagine you have characters goes from young to old, and their body proportion varies between 6-head to 8-head, and somehow we will like to make a chest-plate for an average 7-head base mesh, and use some magic to make it fit on all bodies.
Is it possible? Has it been done?
Most modular character system assume consistent body size, I just can't recall a game that looks semi-realistic and can somehow still avoid making armors for different body size.
If you have got any tips, let me know!
EDIT: And by the way this is not for background characters (aka random crowd), but rather the main character and key NPC, to enable player customization.
Replies
Of course it's something else if you want to fit one armor plate on a slender young woman and an very bulky man.
If it is about re-using assets you might want to use some kind of morph targets.
Overall I would say it can be done - to some extent.
I have to admit I don't know of a game which does something similar.
I might have picked a bad example, because an armor would have given us more leeway, but imagine a star trek like space suit, that kind of tight-fitting clothing, I had a hard time imagine a good way around.
We probably have to model by male/female body type, but then do we have to split by body proportion again? That's where I would like to hear some options other than modeling 6 times per clothing
https://www.gdcvault.com/play/1022085/Innovations-in-The-Sims-4
https://www.youtube.com/watch?v=JGyNWMlmNys
https://www.youtube.com/watch?v=6s5Pni33g4Y
UE4 can also scale bones at runtime. See Morphie's Law, it even uses the base epic mannequin.
If I am not mistaken GTA San Andreas had the main character gain/lose weight based on eating and exercise.
Besides that, morphs have basically been around since the PS2 days. Briefly worked on a sport MMO myself which used body morphs for fitness level, IIRC the source assets where standard, skinny and fat.
Overall the difficulty is mostly about asset creation : how to create and maintain the variants, manually or automatically.
"One of our lead artist mentioned doing this: imagine you have characters goes from young to old, and their body proportion varies between 6-head to 8-head, and somehow we will like to make a chest-plate for an average 7-head base mesh, and use some magic to make it fit on all bodies."
Beware of "fake good ideas". Going from young to old sounds great in theory, but in actual practice this can look grotesque as there is more to human morphology than just scaling things up and down. Sounds like a big fat feature creep and waste of time waiting to happen imho
Yes and here is video for it:
> Besides that, morphs have basically been around since the PS2 days. Briefly worked on a sport MMO myself which used body morphs for fitness level, IIRC the source assets where standard, skinny and fat.
The Sims 4 talk argue that while morph target works, you will need a custom morph for every assets because they are topology dependent, and morphs are memory/storage intensive when you have so many of them.
So they baked specialized displacement map for base mesh and use it to morph the clothing assets based on body size, and then use assets' own vertex color to interpolate how much the assets should follow body form (a tight gym vs long dress).
> Beware of "fake good ideas".
Yeah my suggestion was to create category of humanoid type, not using some magic age indicators.
In my case I've taken one cloth and sample body (left) and adapted it to a set of different body types (right) automatically. The cloth was multi-layered and very difficult to nearly impossible for manual fitting within any reasonable time frame.
Also there've been examples of similar approaches by Hans Goddard (https://vimeo.com/166291982 check ~3m 30s), Chad Vernon (https://twitter.com/i/status/1114752700954992640) and others (https://vimeo.com/284146878).
So you did something a long the line of "storing a nearest body vertex delta transform which then is applied relatively" (thus requiring the same base mesh and vertex order) ?
Nope, wrap deformer works this way, the principle of RBF is more complicated and implies the use of some really big matrices.
You can also check the blog of the author of last video above.
http://www.polygon.me/2017/12/rbf-based-bind-conversion.html
http://www.polygon.me/2018/08/rbf-character-conversion.html
and also this
http://www.marcuskrautwurst.com/2017/12/rbf-node.html
UPD: In short, if your source and target meshes has N vertices, this algorithm builds a Nx3 matrix which represents a linear space transformation / warping from source to target. If you multiply the matrix NxN representing your source mesh by this warp matrix, you will get the target mesh. And if apply it to any other mesh (MxN matrix), it will deform exactly the same way, conforming to the target body.
P.S. Yep, it's a somewhat math-heavy stuff but it worth the efforts for sure.
Curious: so we are using RBF Solver to retarget the equipment to whatever body size we prefer, right? After that, are we at a point we can re-target the binding for equipment as well? I see your second reply, people are retargeting binding for base mesh already, so it depends on if the precision is enough to retarget clothing such as your example?
Again, new to this, so excuse my naive understanding
Also the more detailed your base meshes are the more accurate the retargeting will be, though working with 25k verts base mesh requires about 30 gigabytes of memory for deformation matrix calculation ^__^. In order to keep memory usage reasonable you need to simplify the base meshes topology (not actual bodies, but the deforming meshes, think of it as a sorta LODs) but loose accuracy a bit too. So there’re some trade offs and caveats, but you can work it all out in order to get the decent results.
P.S. The example with mGear is a bit different matter since this is just a joint rotation rbf for rigging, not mesh-based rbf.