blending textures from model to model

[deecue]

Ok, I am doing a somewhat experimental piece dealing with the ungrowth of a fetus down to ovum. I am now doing tests for the geometry and it looks like I will be going down the blend sop route with having 16 stages modeled and blended from one to the other. So far, two questions have been raised:

1: Since the blend sop is based on point number and position, each of my models will have to have the same total number of points. Second, their position will also have to relate somehow from stage to stage. So how would you go about doing this? Would you make the full fetus and copy it to start molding it down to the more abstract creature that it becomes? I figured this would be easier than trying to model the abstract blob at stage 1 or 2 and try to mold that in to a good looking fetus with detail. Any suggestions on that would be wonderful.

2. Since each stage will have to have it's own texture(s), how do i go about blending the texture from stage to stage? I know the blend sop has the blend texture coordinates param. but that isn't taking care of the actual texture blending itself, just the coordinates. So any help with that will be great as well.

And of course if there are any other approaches, thoughts, OPs, etc any of you may have, they are more than welcomed.

Thanks a lot everyone,

Dave Quirus

[Mcronin]

1. That'd be how I'd do it.

2. To mix the textures or shaders, go into VOPs and make a new surface shader. Connect a Color Mix to Cf's output, and then hook your textures or other shaders into the color mix. Use the bias to mix between them. Try the different Adjust Bias settings and see which one works best for you. You can daisy chain several color mix operators to blend between as many textures or shaders as you need.

[edward]

If you have nice meshes, the ray sop might be able to help with blending between topologies of differing point counts.

[anakin78z]

I'd also think about blending in comp, rather than writing a shader that blends between 16 different texture maps . That way you could also render seperate passes to controll blend, if you wanted something other than a straight linear blend.

Something to think about....

[deecue]

Thanks everyone for your suggestions. A couple more things to add...

I can't figure out what the difference is between the blend sop and sequence blend sop. I tried multiple different setups and each one blended the geometry exactly the same. So a good explanation of that would be helpful.

Mcronin: I went ahead and did that in vops. great suggestion and i would love to go down this route, but i need to be able to blend displacements as well. if i wire two texture models in to the color mix and each texture model has it's own diff map and bump map, then they blend together wonderfully. but there are two things. i added a uvproject and shading layer parameter to the texture models to give them uv coordinates. i set it up so they had two layers of uvs in both vops and in sops. but for either uvproject at sop level, i can't see my texture in the viewport, just a grey model with the blue handles. so i have to render each time i want to adjust the projection. is there any way to fix this?

also, i hear a lot about not using bump maps and try to use only displacement maps as the latter will actually alter the geometry, but the first just visually makes it look different or something on those lines. is there a way to bring in a displacement map in my vop net to add to the texture model and have the colormix blend together. or should i just stick with the bump parameter inside the texture model?

edward: can you tell me a little more about how i could use the ray sop? i am unfamiliar with it except for reading the docs on it and trying it out for a little bit after your mentioning but did not get far.

anakin: that is def another alternative i didnt think of. so are you saying you would render out the model for the whole animation 16 times for each different texture. then mix them in a composite afterwards?

thanks for all your help on this guys.. this one's my senior thesis and is pretty important to me.

[anakin78z]

Yep, that's pretty much what I was saying, although you only need to render the parts where the blend would take place. That would give you a lot of controll over the blend, and would reduce re-rendering to make changes. And you could render 'blend maps' to controll blending. So the blend could start in one or more places and grow outward from that, instead of having a straight dissolve.

Depending on how large your displacements are, this may not work for displacement.

P.S. The difference between displacement and bump mapping is that displacement actually changes your geometry, while bump mapping only changes your surface normals, making the light think that your surface actually looks different than it does. As long as your displacement isn't large, the only place you'll see a difference is along the edges, which would stay smooth with bump mapping, but will be displaced when using diplacement.

Did that make sense?

-J

[deecue]

odd.. for some reason my post didn't go through from a couple days ago..

anyways, i just wanted to say that yes, that made complete sense...

and by the way edward, i figured out what the ray sop was.

thanks,

dave