Hi everyone,

The character I am currently working on does not need to animate or do any kind of movement whatsoever. But I do want it to have different stilled poses.

I had planned to just rig it anyways and just pose it to each state, but I don't know if that is the only way to go.

Anyone else have a better way to do it, or is this it?

Thanks,
dave

I don't have any answers but if you plan on using bones, I've got a few tips.
- Make your entire skeleton out of “No Kinematics” bones chains. Since you're not animating, real rigging would be a waste of time. Pose it using the Pose tool. This allows you IK manipulation that gets “baked” as rotates. So it gives you lots of freedom in posing your character the right way using either the “rotates as FK” method or using single-frame IK.
- Capture it using the regions method. This allows you to painlessly add more detail to your model at any point in time. Before you even try capturing, make sure you do an initial pass at setting up your capture regions first using the Edit Capture Regions tool. Use the shift+w hotkey to use opaque pill mode when in shaded view so that you can see whether you've captured all your points. Make sure they have lots of overlap at the joint areas for a smooth deformation. To prevent collapsing, add extra bones in the areas like the crotch. In 6.1, you can layer captures on top of each other if you turn off the “destroy existing weights” parameter in the capture sop. This means that it's a lot easier to blend between the effect of primary bones for capturing and secondary bones for deformation.

You can create a channel group of ALL animation channels on your character. Even if you're not animating you do need to save these channels (save a pose) so goto frame 1, key, pose… frame2, key, pose… etc. The docs say you can fetch a snapshot of the rotation angles of your bones at any given frame (regardless of whether you use IK or FK to pose) , in effect fetching a pose which can be saved out to a file or even slapped onto a totally different character. This is something i'm experimenting with myself and here's my problem …

I have a channel group of my entire character and i'm trying “/obj/@character” in a fetch chop with * in the channels field. But I get “ Error: The specified path is invalid” anything I type in the field gives me the same error

I'm trying to play around with the “Keyframe Pose Interpolation” thingie and other alternative techniques mentioned in the CHOPS docs. I hope someone can shed some light on how this can best be done

Thanks

thanks for all the help and info everyone..

as i am completely knew to this whole character and bones side of the 3d world, i was wondering if anyone knew of a good tutorial or video explaining things such as weights in your rig and geometry deformation.

i've gone through pretty much all the videos at sidefx and 3dbuzz but most of them just deal with complex bones and relations in them, and not as much about the geometry deformation.

i ask this because i am having a somewhat difficult time trying to get my character not to distort too much. i am trying to get the capture regions to overlap as much as possible and everything seems to be smooth at joints such as a knee or ankle.. but the area where a leg attaches itself to the body is becoming quite tough. the section where the butt and the leg meet is getting distorted pretty bad and i thought that maybe weights would be an option to getting it better.

thanks,
dave

talkien: I'm not sure that the Fetch chop supports the @ notation for groups. You might have to do something like `opglob(“/obj/@character”)`. The thing to note about the Fetch though is that if you're using these tracks to export to where you fetch them in the first place, then an infinite recursion error will result. The easy way around this is to lock your fetch chop before exporting.

deecue: The problem with the leg to the body is what I meant about an extra crotch bone to prevent collapsing. i would spread the whole capture region of the crotch bone to encompass the entire hip area.

The fetch chop popup help says I can fetch channel groups with /obj/@group. Will try opglob and see how it goes, and thanks for the locking tip, hasn't happened yet but its good to know

ok, i think i got a pretty good handle of how the weights work (for now atleast). it occasionally gets wierd. such as when i go to paint the weights on to the bone, if i go to select another bone to paint weights, it completely forgets the first bone i did. even if i paint weights on one bone and get out of the paint op. then go back in and repaint another bone. it only seems to remember the last bone painted. so i just end up going to the edit weights op and manually adjust each point in the spreadsheet..kinda annoying but works.

and now the bottom and crotch looks pretty decent..thanks for the help on that one edward. so im pretty happy about that.

the only thing still bothering me is the way the upper thigh gets deformed when brought in to the stomach. it doesnt make a solid crease in the leg like you would expect it to. its more like a force is pushing in to the upper thigh and looks wierd. i've tried messing with the weights in the area but still not much luck. i dont know if i should just add more bones in that area or what. any opinions would be great. here is a image of what im talking about.

thanks,
dave

Normally, and this is common for all joints, your weights will vary depending on whether they are on the inside or the outside of a joint. The blended smooth region should be much less on the inside. Notice when you bend your own leg it creases along the bikini line extension. This dip you're getting in your image is because your points in front on the upper thigh area are being influenced too much by the pelvis/spine bone. This area should favour the thigh a lot more so as to get that crease and prevent the thigh from collapsing. Try 85-15 for starters, you may need to go higher. The butt (outside) will be smooth, more like 50-50

Regarding the changing weights while painting, make sure the combined weight of all influencing bones adds up to one. This kinda behaviour occurs when the weight adds up to less than one, so Houdini tries to guess. Personally It saves me a lot of work if I first hard edit everything to 1 using the spreadsheet, then paint to smooth, then fine tune individual weights by hand again using the bone handles

Tip: If you hit ‘d’ with your mouse in the viewer, go to the Misc tab and turn off Specular Highlight. That might help you in seeing the weighting colours too.

As for painting weights, it seems to work for me. If you make your Pose handle persistent, you can move your legs around while painting without exiting the tool. You might need to turn it on/off in the left toolbar to pick different bones though. What version of Houdini are you using?

ahh, no specular.. nice.

im using 6.0.383 and unfortunately can't have it updated as of yet.

it just acts wierd. like if you see the orange and the blue bone in the image above at the waist. if i start to work on the orange and paint away (middle mouse) any weights on the model, it suddenly fades to white (which is good). and there is some distortion in areas where the blue bone has some weights which is expected. so i select my blue bone and start painting away (middle mouse) some of the weights on my geometry where i don't want it influenced. and it ends up replacing the blue with orange (my other bone) instead of going to white (non-weighted geometry).

i don't know if that made sense at all, but it's just odd for me. so i've just gotten used to setting weights through individual points\spreadsheet.. kinda tedious but kinda nice as well.

and i took some of your suggestion talkien and fixed the weights in those areas and it looks much nicer. Question though.. what if the weights equal more than one totaled? not good?

mucho gracias,
dave

not too sure but i haven't had problems with weights more than 1, just less. Maybe it just uses ratios then

talkien:
The Deform SOP will normalize the weights on deforming so if you have weights which don't sum to 1, it will be implicitly made to do so.

The only problem that can occur I think is if you somehow managed to introduce negative weights.

deecue:
The effect you're seeing is that the weights are being normalized as you paint. In your situation, when you decrease the blue, the orange gets increased so that the weights sum to 1. You can change this behaviour by hitting the p (for parameters) key with your mouse inside the viewer while in the Paint Capture Weights tool. Change to the Op Dialog tab and scroll to the bottom. Turn off Normalize weights.

Thats sort of what I meant by Houdini Guessing the weights.

Anyway I figured out how to get channel groups into the fetch chop
Node: /obj/
channels: @character

The effect you're seeing is that the weights are being normalized as you paint. In your situation, when you decrease the blue, the orange gets increased so that the weights sum to 1. You can change this behaviour by hitting the p (for parameters) key with your mouse inside the viewer while in the Paint Capture Weights tool. Change to the Op Dialog tab and scroll to the bottom. Turn off Normalize weights.

that makes complete sense..


thanks, you guys are awesome…

dave

tallkien
Thats sort of what I meant by Houdini Guessing the weights.

Hmm … Let's say you have a point that is weighted by two bones, one with 5 and another with 20. How do you expect the point to behave? Is it not reasonable to assume 5/(5+20)=0.20 and 20/(5+20)=0.80 ? ie the point is weighted 20% to the first bone and 80% to the second bone.

not too sure but i haven't had problems with weights more than 1, just less. Maybe it just uses ratios then

hehe, Thats sort of what I meant by using ratios

What I meant by Houdini guessing the weights was what you explained as normalizing weights that added up to less than 1, just learning to speak geek :wink: