rtmw3d: keypoints z prediction

[philchaub]

i've tried rtmw3d in inference, and i'm very surprised in Z prediction results.
i've tried on several images, with classical poses (only one character, walking) .
As explained in the documentation, I thought the values ​​on the Z axis would be distributed around the root, and therefore the pelvis.
So I expected positive and negative values ​​whose amplitude would be consistent with the scale of the x and y values.
But what I get are only positive values ​​distributed over a very short scale. For example, left hip = [219.62266540527344, 381.46295166015625, 6.810750484466553] and right hip = [135.74488830566406, 385.10980224609375, 6.794205188751221]

how it's possible ?