Why can't software translate a shape fro one mesh head into an (almost) matching shape for another?

[Jennifer Boyle]

Everything in SL is actually a collection of numbers intended to be interpreted a certain way by software. An avatar shape is just a collection of numbers that, when processed by an algorithm, let software render a three-dimensional object. I do not understand the process, but it seems obvious that the reason that different shapes are required to achieve (nearly) the same appearance is that the algorithm is different for different mesh heads. That being the case, it should be possible for software to produce a shape for one head that produces an appearance close to the appearance produced by another shape for another head.

SL residents have spent thousands, if not millions, of hours tweaking shapes while trying to keep their same features when they've got a new mesh head. Even if the task is very complex, and there is no better approach than  brute force trial-and-error, surely it could be completed within a short enough time to be useful. It would be useful even if the result was not perfect, because one just closer to the desired appearance than the original would be easier for a person to use as a starting point for tweaking.

I'm now, with a new generation of improved mesh heads, facing the daunting task of trying to produce a shape for a new one that result in a face that looks like mine. I would gladly spend some money to decrease the amount of work it will take, and I would gladly run a program for days, if that's what it took. I'll bet thousands of others would, too.

Why doesn't such software exist?

 

[Wulfie Reanimator]

Short answer: Because it's hard.

Longer answer: The system we use for shapes is too simple, and literally cannot work the way you're suggesting. Mesh heads work by having a "base model" (the one created in 3D modeling software), which is then rigged to a relatively simple "skeleton" with few (about 40+) bones which can be used to influence the mesh by "weight." The weights determine which bones and how much they affect the mesh if they change. SL "shapes" only affect the base skeleton, and the mesh head is the one who decides what it's going to look like.

That's a very simple system compared to completely shrink-wrapping one model to another, and makes it impossible for two models to become even close to each other if they aren't already similar.

To be clear, mesh models can be transformed almost 1:1 with other models, but it would require the models to be set up very differently, for a very different system. One example is Shape Keys in Blender, but it requires that the two models have exactly the same amount of detail. I don't even know if a generalized "morph any 3D topology to another" is even possible. The algorithm for that might have to be inhumanly complicated.

Edited August 8, 2020 by Wulfie Reanimator

[Chic Aeon]

Just to note   I have found some brands do a really good job of following the  default Linden avatar shape (just a little tweaking and it looks  very similar) and others (several) that have made their head so VERY different that when shapes used from the the non mesh avatar or indeed many other brands  -- look beyond deformed. So it IS possible, just not what some (read that as MOST) creators do.   I have no idea how mesh heads are made. I only see the end results and I agree they aren't pretty.   

There are some heads (again MANY) that have no way at all to get the look you want. I have been making shapes for a dozen years and know what sliders change what --- simply NO WAY.    That is one of the main reasons folks need to DEMO and not just buy from the vendor photo (oh such a very bad idea).  

Things are most likely not going to change, but I do understand the OPs frustration.  

[Emma Krokus]

Chic, would you share the brands that can achieve the look of a default avatar head easily?

Like Jennifer, I have spent literally months trying to achieve a look that feels like "me" with a variety of heads... suffice to say, my head is still not mesh. 

The closest I've come is with the Ruth 3.0 head... but it is a bit "blocky" to my eyes...

Emma  

[Chic Aeon]

9 minutes ago, Emma Krokus said:

Chic, would you share the brands that can achieve the look of a default avatar head easily?

Like Jennifer, I have spent literally months trying to achieve a look that feels like "me" with a variety of heads... suffice to say, my head is still not mesh. 

The closest I've come is with the Ruth 3.0 head... but it is a bit "blocky" to my eyes...

Emma  

For ME it was altamura -- which of course isn't one of the top brands so issues there. This was both female and male FREE avatars.  Personally I am wearing the Genus STRONG (free) head from awhile back. When I saw the vendor photo I was pretty sure it could look like me. Honestly though I don't remember how much I tweaked it to get it "AS" me :D.  But it wasn't hard to do if you know your shape sliders. 

Ruth (started by a good friend of mine back in my Opensiim days) isn't bad. That gal better than the guy in my estimation. I think real life got in the way of that project :D.   But yes, it was made to be VERY low poly which is great for Opensim (what it was designed for) but not really what we are used to so far as triangle count here. 

 

It was difficult for me to move to a mesh head too. Eventually I got a Lelutka non Bento head (years ago) and wore that until these last few months when I switched to the Strong head.  Now (NOW ) it feels normal but it took awhile LOL.    I did have a guy friend recently who had tried many heads over the last three or four years and never could get back to "himself" until the new altamura  gift came out last month.  So he is beyond happy.  One guy friend is wearing the Exmachina body and head and he looks like himself again also.  It is a very nice body but really difficult to get clothes for. 

 

It is HARD. Agreed.   I can't say I have tried many altamura heads only but I would imagine they would be very similar to the all in one style.  My alt is wearing a free gift head from  altamura a few years back but she wasn't trying to reproduce a look -- just look good LOL.

 

 

[Emma Krokus]

Hi Chic,

thank you for your reply!

I have really tried with Altamura  (that brand is my go-to) - I have all their gift heads, gift bodies, and a couple bodies paid for - but could never get the heads to look right! One of their CSR's even tried to get my shape right to no avail. The Genus Strong I have also, and I am happy with it... for my alt !!

It seems I am the opposite to you - haha. Please tell me the ones you could not get YOUR look with - they may just work for me !

Emma  

 

[Odaks]

9 hours ago, Chic Aeon said:

not just buy from the vendor photo (oh such a very bad idea). 

How very true! If you gaze around the vendor pictures of the heads at Catwa, for example,  you can hardly tell the difference between them all. But when you actually put he demos on, the differences stand out a mile, and those differences are very significant.

Edited August 8, 2020 by Odaks

[Nalates Urriah]

@Jennifer Boyle The short answer is because of creative freedom. Understanding that gets complex. But the complexity is the reason it going to be practically impossible (impractical) to provide the software you want.

Think about it. A mesh head is a series of vertices that describe the head. Each vertex is a X, Y, Z representation of a point in 3D space. Some thing like <124.15, 216.28, 30.22>.

Modeling tools save the modeler from dealing with the actual numbers. They visually sculpt the head. So, each head has a different number of vertices with each in a unique location. If the vertices were all in the same place and same number of them then all heads would look the same.

The next level of complication is in weighting the vertices. The head needs to have eyes that blink, a mouth that opens, lips that smile, etc. To do that we have to tell the system how each vertex is to move in relation to a bone, say the jaw. The values we call weights are the information that tell the system how closely a vertex follows a bone. In SL there are four values that tell the system how the vertex moves in relation to four possible bones.  These values are also handled by modeling software and allow creatives to paint with a brush to weight masses of vertices. They don't really consider the numeric values.

The point here is it is very impractical to expect designers to strive for numeric consistency between various heads. Without that consistency the software you want would have to know all the values used in each head to be able to cross translate a shape from one to another.

Making that even more impractical is that vertexes in nearly the same place in a head are weighted to different bones. This is why some animations don't work well with some heads and others do.

To eliminate all the complications would require removing creative freedom from the design process. That would make all heads look pretty much the same. Not what most of us want.

It took me a long time to find a mesh head I could make look similar to my classic head. There are a large number of heads I just could not tweak to the look I wanted because they looked different. They could only be tweaked so far from their basic look.

The shape side of the viewer deals with bones. The shape editor has no knowledge of the weight values and vertex positions. When you tweak a shape you are eyeballing what moving the bones does to the mesh without any need of all those math values. The use of those numbers is buried deep in the render engine. Most of us never need to know anything about them.

[auntiemisha]

I got the free CATWA head and was having a terrible time trying to get the eyes to look anything close to what I wanted. I normally use the RuthToo head. So I put the CATWA head away until recently.

Then I realized something -- it wasn't so much the eyes, it was the eyebrows! So I created an "eyebrowshaper" (so many different names for that system layer item, "system hair", "shaper", "eyebrow") and set almost all the brow settings much lower.   Now the eye area looks more like what I am used to!

I still have issues left that are enough of a bother to me that I'm going to continue tweaking.  But it feels close enough that I may take the head out for a spin and see how I feel about it in action.

1) The old system skin I love (TuTy's Nadia Pale skins) leaves black splotches (the lashes I think) on the eyelids.  I cover it up with eye shadow but as I also like a natural look from time to time, I need to find a fixer.

2) I'm still not completely satisfied with the nose. I slide the sliders but nothing has quite satisfied me yet.  (It may be the #3 influences how I see the nose).

3) The subtle age lines tattoo I have just looks like smudges on the Catwa head, so I haven't used it.  The wrinkles I have seen on the market seem to be for much older than I would want.  But I also don't want to have the smooth doll face look.  I might have to try my hand at making my own wrinkles.

4) The overall face proportions are different but the differences don't seem to bother me as much as the facial features issues. I'll probably keep tweaking until it feels more "right" to me.

I am not sure why I have been hyper-focused on tweaking the CATWA head lately.  I only hope it doesn't lead me to hyper-focus on the GENUS strong head that I have barely touched. 🙂

Hmm has anyone blogged step-by-step details of what they had to change to get their mesh head to look similar to their previous head (system or mesh)?

 

RuthToo:

 

 

 

CATWA Freya Gift:

Edited August 13, 2020 by auntiemisha
word choice error