OK, thanks!

Helmer

Thanks for all the help!

The texture strength was at 1, but Vexiphne was right, translucence value was at 0.5. However, after I changed it to 0, it still didn't work out right.

Anyway, by editing the MAT files from the GLH package itself, I can get it to work. I was just wondering if there was some simple adjustment I could make, either in the material room or as a simple addition to the MAT file.

Thanks!

Helmer

Thanks!

I'm new to Poser, and so far I've mostly being using MAT files.

But I guess it's time for me to start exploring the Material Room!

Especially now that I've discovered that some MAT files don't work under Poser 6. :-(

Thanks!

Helmer

HI Gora,

Ok, thanks. So you're saying to find a Miki  texture and a V3 hose and combine them in Photoshop and then use it as a Miki texture. I haven't tried it before but it sounds doable.

Thanks!

Helmer

Hi,

Just a follow up.

I've looked a bit more closely at some INJ files, and I now understand that the INJ PZ2 files include readscript's with paths for the morphs, so I guess that answers part of my question.

However, I also looked at some FC2 files, and they seemed to just set the values of dials and not inject anything. There were only lines of the form

targetGeom Asian1
            {
            keys
                {
                k  0  0
                }
            }

In that case, so I either have to look through the FC2 file and make sure I manually inject all the required INJ PZ2 files, or do a INJ ALL?

Thanks!

Helmer

Hi SamTherapy,

Thanks a lot! Very helpful.

I was dreading having to deal with huge files and endless lists of dials.

Helmer

Hi guys,

I just realized that I was wrong. It is not true that the X-rotation always is global (when using YXZ rotation order).

I decided to sit down and really do the math. I wanted to make sense of the experiments conducted by Ronstuff at http://market.renderosity.com/mod/forumpro/showthread.php?thread_id=984280

Summary: When using the YXZ rotation order, Y-rotation is around the local Y-azis, Z-rotation is around the global Z-axis, and X-rotation gives a global rotation, not around the X-axis, but around the axis that results when you apply the Z-rotation to the X-axis. If the Z-rotation is zero, then the X-rotation is global. If the Y-rotation is zero, then the X-rotation is local.

I thought I'd share it with the forum. It may be a bit more math than some of you feel like, but I will try to keep it simple.

I will assume that Poser uses the rotation order YXZ. That means that every rotation is decomposed as

R(V, s) = R(Z, a) R(X, b) R(Y, c).

Here R(V, s) means rotation of s degrees about the vector V. I read products of rotations from right to left. In other words, every rotation can be written as first a rotation around the Y-axis, then around the X-axis and finally around the X-axis. All the rotations are around the GLOBAL axes.

Rotations don't commute, but here is a general product rule

R(V,s) R(W,t) = R(R(V,s)W,t) R(V,s).

If you manage to penetrate the mathematical notation, it simply says that first rotating around W and then around V, is the same as first rotating around V and then rotating around the vector that is obtained when you apply the V-rotation to W.

I will start with a rotation

R(V,s) = R(Z,a) R(X,b) R(Y,c),

and change the Z-rotation to R(Z,a+d). Now

R(Z,a+d) = R(Z,a) R(Z,d) = R(Z,d) R(Z,a),

so

R(Z,a+d) R(X,b) R(Y,c) = R(Z,d) R(Z,a) R(X,b) R(Y,c) =
R(Z,d) R(V,s).

This simply says that changing the Z-rotation from a to a+d adds a global Z-rotation of d. Just like Ronstuff said.

Now let us change the Y-rotation to R(Y,c+d). Then we get

R(Z,a) R(X,b) R(Y,c+d) = R(V,s) R(Y,d).

Now we use the product rule above and get

R(V,s) R(Y,d) = R(R(V,s)Y,d) R(V,s).

But what is R(R(V,s)Y,d)? Again, if you can penetrate the notation, it simply says rotate d degrees about the vector you get when you apply (R(V,s) to the Y-axis. If you think about this, you will see that R(R(V,s)Y,d) R(V,s) simply is the local Y-rotation of d. Again, just like Ronstuff said.

Notice how extra factors at the left (end) give global rotations and extra factors at the right (beginning) give local rotations.

Now let us change the X-rotation to R(X,b+d). Then we get

R(Z,a) R(X,d) R(X,b) R(Y,c),

and if we apply the product rule we get

R(R(Z,a)X,d) R(Z,a) R(X,b) R(Y,c+d) = R(R(Z,a)X,d) R(V,s).

So changing the X-rotation gives a global rotation of d, but not around the X-axis but around the axis that results when you apply R(Z,a) to the X-axis. This again agrees with what Ronstuff said! (Except that there was a typo in his summary, which mixed up Y and Z when describing how the X-axis behaves.)

If zRot is zero, then R(R(Z,a)X,d) = R(X,d) so we get a global X-rotation.

If yRot is zero, then we get R(Z,a) R(X,b) R(X,d), and since the extra term is on the right, it represents a local X-rotation.
 
If you're still alive, you may also want to know that instead of bringing the R(X,d) term to the left to get a GLOBAL X rotation, we can bring it to the right. Some funky application of the product rules gives R(V,s) R(R(Y,-c)X,d), which means that you get a LOCAL rotation around not the X-axis, but the vector you get when you apply a rotation of -c around the Y-axis to the X-axis.

OK, this was probably more than you wanted to know, but I thought it may be of interest to some.

If you want to change this behaviour, you can manipulate the rotation order in the joint editor.

Helmer

Hi VK,

Thanks for your post.

I'm a professor of mathematics, so it took me some time before I understood that CG people used three axes when they talked about Euler angles!

To me its natural to think in terms of DOFs, and think of the rotation order as how you parametrize an arbitrary rotation and break it into a sequence of rotations. At first I was confused by how "simple" rotations about one axis could cause problems, but then I realized that if you use global coordinates, your starting point may already be in a gimbal lock position.

I liked your picture!

Helmer

Hi Kuroyume,

Thanks for all your comments!

I agree that what I wrote earlier was wrong. My thinking was correct, but the keyboard was moving faster than my brain! :-(

But I'm still a bit confused about the meaning of  "joint order" in Poser. I assume that it refers to the Euler angle convention, but does it also affect how the three rotations are carried out, meaning whether they are local or global? It seems to me that y local and x/z global (meaning that yRot is with respect to a local y axis while xRot and zRot are with respect to the global x and z axis) is the default in Poser, but can I change this by changing the joint order of an object?

Thanks!

Helmer

Hi Kuroyume,

Thanks for the help! My understanding is that part of the problem is that the term "gimbal lock" actually refers to two related problems.

1. When parametrizing rotations using Euler angles, the problem is that we are tied down by a specified order of rotations. The advantage of using quaternions is that then there is no rotation sequence, since everything is done in one step.

2. The original gimbal problem has, as far as I understand, to do with the fact that, kind of like in Poser, the gimbals are different. If we look at the picture of the plane in < http://www.fho-emden.de/~hoffmann/gimbal09082002.pdf >,
   the yaw is linked to the table, so it is global, while the roll and the pitch are local.  In this case, the problem is that we get coinciding axes. The roll (local) and the yaw (global) may coincide.

To be honest, I'm not sure if I really understand the picture in
< http://www.hq.nasa.gov/office/pao/History/alsj/lm_imu.gif >,
but I believe that there is a similar thing going on there, namely that the gimbals are somewhat different.

I believe that it is misleading to talk about Euler angles and quaternions when talking about gimbal lock in Poser. In Poser we are not tied to any specific order. However, the y-local, x/z-global design, obviously leads to the same kind of problem as in 2.

So my understanding is that in Poser the problem that can happen is that y and x can coincide or y and z can coincide.

To be honest, I still don't fully understand exactly why the BODY/hip trick works, but it seems that it somehow separates y from x/z.

Thanks!

Helmer

Hi kuroyume,

Thanks for your posting. I think I was making it too complicated. Is what you're saying that the point is that I isolate y from x/z, and that either y on BODY and x/z on hip or y on hip x/z on BODY both will work?

Thanks!

Helmer

Hi,

Thanks to Helgard and Dr Geep for the replies.

I believe I have a reasonably good understanding of the general concept of gimbal lock. My problem is with how it works in Poser.

Why does Ockham and other say that using yRot on the body and x/zRot on the hip will solve it?

I don't think I understand the relationship between body and hip.

Thanks!

Helmer