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Subject: changing joint order and adjusting joint zones


cal401 ( ) posted Sat, 20 October 2001 at 12:24 AM · edited Fri, 29 November 2024 at 8:55 AM

Has anyone figured out how to use the joint editor? I've made a change to the joint order of the P4 male's shoulder and need to adjust the joint zones. I'm not exactly sure how to go about it or if it is even worth attempting. Any suggestions would be appreciated. Cal


Miss Nancy ( ) posted Sat, 20 October 2001 at 1:31 PM

Attached Link: http://www.3dmenagerie.com/goodies/tut/jps.htm

bloodsong did a tutorial on this (see attached link). it's not too hard to resize the zones, change zone arm lengths and angles - just rather tedious IMVHO. what led you to change the joint order?



cal401 ( ) posted Sat, 20 October 2001 at 3:09 PM

file_222356.jpg

Thanks for the link! I think that has me pointed in the right direction. I am working with a figure on a racing-style bicycle with "ram's-horn" handle bars. When I tried to move the figure's hands to the curved part of the handlebar, I discovered that they CANNOT be moved into that position with the default joint order. The joints go into a "gimble lock", where both twist and bend are doing the same thing; bend no longer functions to move the elbow away from the body. To demonstrate the problem, take the default P4 nude male or female (I haven't check the other figures, but they probably behave the same way) and set the shoulder front-back dial to 90. This will make the arm extend directly out in front (sort of a Roman-salute pose). Now try to lower the arm directly to the side, keeping it parallel to the body's median plane; it can't be done, it can only be rotated along its long axis and rotated back to the Poser neutral position. Bend should move the arm at right angles to front-back, but it does not. No matter how you get into the "Roman-salute" pose, front-back is the only dial that will move you out of it, and you are restricted to one plane of motion; needless to say, real people don't have this limitation. (Frankly, I'm surprised that people haven't noticed this before.) Changing the joint order to YXZ fixes the "gimble lock" problems, but messes up the joint parameters, causing part of the upper arm to be left behind when the arm moves. As I begin to dig into this, the main problem seems to be that the joints now have the wrong attributes associated with them. Front-back now has the twist attribute associated with it, which is probably why the deformation is messed up; any idea how to re-map that? Thanks for your help! Cal


bloodsong ( ) posted Sat, 20 October 2001 at 7:15 PM

heyas; cal, you have to go into the cr2 and change the order and appellations of the joint parameter entries of the body part. if you made y the first rotation order, then it is going to have that twist bar, because the first rotation IS twist. you can try to change it in the cr2 to be an X again by changing the name from twisty to rotatey... but this might cause unknown problems. (actually, the other day, i was speculating about putting more than one twist bar in the cr2, but you probably don't want to try that ;) ) you should use a cr2 editor and look at the limb you want to change, and one that looks the way you want it to look. the joint/joint/twist are the jps, and then the rotate/rotate/ (i forget, and i cant run my cr2 editor now)whatever right after that are the rotation dials. they have to match the order in which they go. so if you swap jointx and twisty, you have to change the names, swap the channels, and then swap the dial channels. did you try bending the shoulder down before moving front/back to 90 degrees? also try setting it to 89 degrees, this might avoid the gimbal lock. actually, it looks as if you need to move the collar forward first, then the shoulder, which will make it even less than 89 degrees. i think you're making things harder on yourself trying to mess with the rotation order, when perhaps posing it a bit differently, or in a different sequence will make it come out the way you want. but hey, knock yourself out :)


cal401 ( ) posted Sat, 20 October 2001 at 8:31 PM

Thanks. If I had ever known that twist had to be first, I had forgotten. However, XZY joint order seems to fix the gimble lock problem (at least in this instance) and avoids the problem with the deformation. (I thought that I tried XZY before and it didn't work.) Honestly, I tried for hours to get the arm into position by coming in from different directions, playing with the collar, etc.. I can't get it done; I'll be happy to send you the file, if you like; maybe I'm missing something. But the bottom line is, it shouldn't be that tough to get to a desired pose; humans don't have a gimble lock problem, neither should Poser figures. As for using a different pose, that's not an option here. This is for a technical animation and the position of the torso and hands/arms is important. On top of that, for the animation and I will need more control over the arms than I have with the default joint order. You definitely have a LOT more knowledge about this whole issue than I do, and I really appreciate your help! XZY joint order SEEMS to be the answer here; can you tell me what problems XZY is going to cause? That is, what things am I going to need to fix to it. Thanks again! Cal


ScottA ( ) posted Sun, 21 October 2001 at 7:51 AM

Attached Link: http://cloud.prohosting.com/3dmodels/poser.html

Download the tutorial at the bottom of this page. It has lots of JP related pictures. He has the Propack Blood. He doesn't need to edit the .cr2 file. The Propack has the option to change the rotation order in the JP editor. Cal: Forget about what X,Y,&Z means. Because they don't always do the same thing from figure to figure. You need to understand the basics of JP's. And they are very simple: 1.)the twist axis must run down the length of the body part 2.)the bend and side-side type axis are swappable. It just depends on what you prefer. 3.)the placement of the handles of the joints are crucial 4.)shperical zones and there placement are crucial 5.)blending characteristics can be reduced by editing .cr2 files. Don't get hung up on the letters X,Y&Z. They are nothing more than names that don't have any real value to the Program. As far as the JP editior is concerned. I've tried to beat that into people heads. But they can't accept it ;-) ScottA


cal401 ( ) posted Sun, 21 October 2001 at 12:18 PM

Hi Scott, Thanks for the link and the information. I understand all of your points, thanks. Changing to XZY joint order completely fixed my problems with the shoulder; a couple of minor tweeks to the fall-off zones and I'm set. I was expecting problems with conforming clothing, but it seems to work fine. So far I haven't found a down side to the new shoulder joint order. The default order is pretty close to useless for any pose that has front-back near 90. I'm surprised that folks can get anything done with the default joint order. As far as axis names go, I just with they would display an axis tripod, as in MAX, so you can see tell which axis to use without trial and error. Any idea why the default fall-off zones are so large? For example, the zones for the shoulder extend way past the elbow. Cal


ScottA ( ) posted Sun, 21 October 2001 at 12:38 PM

If I understand your question right. The answer why the zones are so big is because the spherical zones MUST encompas the entire body part. That means they actually overlap into the next body part. Because of this fact. The radious of the sphere can make or break good poseability. So sometimes you'll see a huge circle around a body part. Because in order for that to pose with as little warping to the parts connected to it. the arc of the sphere needs to be large. And since you can't have a large arc. Without also creating a large radious. You end up with a big ass circle around some body parts. Sounds complicated. But it's really not. Example: A softball has a much smaller radious than a beach ball. That's what makes it smaller. Therefore...the softballs radious is arced much more aggressively so it gets back to where it started sooner. Am I babbeling now? ;-) ScottA


Jim Burton ( ) posted Sun, 21 October 2001 at 2:24 PM

file_222357.jpg

I got his hands on the handlebars without modifying the Dork, but your tight, he does go into a really bad case of Joint lockup - and look at his shoulder too, its sort of broken! I think the reason nobody ever noticed this is hardly anybody uses any of the stock P4 figures other than the Posette, I know there are problems with the horse too (vertexes in wrong group) and the cat (open seams), too, they are also the only other ones I've ever used - other thamn the fish, which seems O.K.! Mikes O.K., BTW, I got Mike-on-a-bike!


bloodsong ( ) posted Mon, 22 October 2001 at 2:13 PM

pro pack? well, you lost me on that one, then ;) x is sideways in the poser universe. y is up and down, and z is forward/back. now which axis is 'twist' depends on which way your limb is pointing ;) i did some experiments once upon a time to try to get the shoulderblade/collarbones to bend better. i didn't have any success at all! if you got 'em to work better for you, then you're ahead of me :) yes, scott, you're babbling ;) the spheres really only matter where they intersect the body part and its parent.


cal401 ( ) posted Wed, 24 October 2001 at 7:34 PM

Scott, thanks for the explanation on the zones; makes sense. Blood, Pro Pack has a joint editor that lets you go in and change the joint order, all of that, with inside the program. I've never used anything else, so I didn't realize it wasn't a regular Poser feature. Jim, do you know what joint order Mike uses? Cal


pragask ( ) posted Wed, 07 November 2001 at 4:04 AM

About joint orders ... From exprimentation - I figure that the joint rotation order is determined by the order of the rotationX/Y/Z in the channels section of the particular actor in the cr2 file ??? If you want to rotate in XYZ, you should set the rotation order in reverse i.e. rotationZ, rotationY, rotationX in the cr2 file . I don't think that the order of the jointX/Y/Z or twistX/Y/Z matters . They just seem to indicate which is the twist axis . About joint zones ... I think the joint zones were created originally for simulation of tendons . But they don't seem to work effectively that way . An easier way to adjust bends is to adjust : 1. the start/end bend angles in the joint editor by directly moving the bullseye cursor of the angle handles in the poser figure . 2. the bulge values in the joint editor panel .


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