Modelling low poly bone spine...Should I have the bones separate?

Taka007

Hey guys. I have a dilemma. I can see pro and con for both and swinging between the two ideas.

I'm modeling a dragon with a bone spine. Now I'm making the retopo. Would you sew the bone into the body have them separate?
Considering:
* Animation & Skinning
* I'm using PBR (Substance Painter) textures
* Polycount & UV space
Which one would you choose and why?



Thank you!

CheeseOnToast

Sew them in, primarily for skinning / animation reasons. The underlying topology of the body doesn't currently match the spine topo very closely. During animation, you'll be hard-pressed not to create little gaps or intersections with the spine.

Having it as continuous topology will also help you bake out cleaner normal, AO etc. and less texture space will be wasted. It'll also be much easier to paint weights for.

Taka007

Thank you CheeseOnToast! It makes sense.

Mark Dygert

If you don't join them they will tear apart and slide around, it might be acceptable, but then it might not, it really depends on the range of deformation in that area, how many polys it adds/saves or if it's going to take a long time to stitch them together. That last one gets worked out in advance with experience. If you know you need them stitched, you start building it to support that.

The example below has AO baked into the main cylinder but the ugly black parts that are normally inside of the spine are starting to creep out as they slide around. It might be acceptable on a quick, fast moving character that doesn't have a lot of screen presence. But then it might be totally horrible if it was a creature as big as a house and it slowly lumbers by you. 

Taka007

Thank you, Mark. Especially for the effort, you put in to explain. Finally, I decided to sew it together, which also meant to change the topology. I'm convinced now that it was the best choice.