Back Muscles
Tutorial by Carl Kidwell

Back muscles had me stumped for a couple of days when I did this skin. I was ending up with something either so subtle it didn't realy look like back muscles or something so exaggerated it looked like malformed lumps on the skin instead of muscle massess. Depending on the skin you are making quite often exageration is something that can be of great use. Afterall we are using a 2 dimensional 'skin' to create the illusion of surface details on a low polygon 3D model aren't we?

Our 'exaggeration' can come in many forms from enhanced lighting to increased depth illusion to more comlpex appearing details than the model itself could accomodate. So finally I have come up with a decent back that suited my needs and struck the balance between exxageration and keeping the impression of what it really is.

As always I highly recommend finding 'source' images when possible to create your art from. Especially if you have not drawn a particular item very often then this is invaluable. Most of the 'backs' of skins I have drawn have actually been armor peices, not flesh and muscles so I took the opportunity to browse through a copy of a muscle magazine and found a back that suited my needs:

Now you'll probably notice this is the back of a female, which I choose on purpose. You see most of the male body builder pictures their backs were so HUGE it made for really difficult subject matter to translate to my needs. When I stumbled across this female back musclature all of a sudden I had what I needed, a great reference pic of well defined back muscle structure, without being grossly out of proportion!

So we move on now to my first step which is (by recommendation) to paint only one half of the skin and later utilize the mirror image technique to complete it. Also utilizing this technique will help you out when you have to actually paint a skin that is actually mirrored on its mappings (that is to say you will only be able to paint one half of it and the mappings will automatically copy that half to a mirror image for you). In the instance I use here you could easily make two different sides but back muscles are usually symetrical so the mirror image technique is very applicable. Also if I wanted to go in an add unique touches to each side after I was done that is easy to do, such as battle scars, or a bandolier, or a shirt with a pattern on it, etc.
 

First image:

So we see above I have painted the general impression of the muscles. I have not gone into great details, and put only the most basic of shading into it. (If you need help with shading see my painting tutorial). Its important to start off by laying out the overall impression first instead of for instance going into great detail on the top half and then realize that you didn't make enough room to allow the muslces to flow properly and have to scrap all your work.

Image 2:

Above in Image 2 we see that I've begun to add more shading detail including highlights and deeper shading under surfaces. If you check my reference picture at the top you will see a reasonable resemblance to the muslce massess although I gave myself some creative flexibility.

Image 3:


Ah, here in Image 3 we see close to the finished product where I have added some 'specular' highlights which help give the muscles a shiny more alive feel. I used white instead of the flesh brown color for the specular highlight. Advanced modeling programs will automatically do specular highlights, as well as some game engines are begining to be capable of it as well.  Depending on what engine you are designing your skin for you may wish to leave off highlights of that nature but most games you are safe with it, and it greatly enhanecs the look and feel of your image.

Image 4:


And here we are in Image 4 I've mirrored the image and copy & pasted it to the other side making a complete back musclature.I also went in and got rid of some of the seams but also left others as it helped show the division of the muscles. Finally for your comparision side by side see below my original source image and final skin:
 
 
Source / Reference Image
 Finished Skin

Well that's it for back muscles, I hope this has been helpfull and educatory for you!

Carl Kidwell
melkior@planetquake.com