![]() From watching the videos of the polar bears it became apparent that
most of the information I had concerned female polar bears rather than
the males. Although the differences between the two are quite small, they
do exist. The male bears are stockier and much heavier, so they would have
to be animated accordingly. With this in mind I decided the most sensible
thing Before I could go about making the model of the polar bear I looked for pictures that would show me both the outside and the biology of the bear. I found pictures of polar bears in various positions and could therefore see how the different bones of the bear deformed in different situations. From looking at pictures of polar bears I was able to determine how to build the body in the right proportions so that it looked like an adult polar bear even though it was make out of blocks. I decided to make the behind and shoulders out of quite complex blocks compared to the leg blocks, so that they would appear rounder. I also decided to add enough detail around the head area so that the silhouette of the head looked correct, but not enough that it needed any detail around the eyes. This was so that the head did not look out of place with the rest of the body, and also so that the model would not look strange without a texture when it was finished.
They raise the back of the ankle up as they walk, however.
With the skeletal information I could see where to break the blocks I had for the legs so that I could recreate the movements as accurately as possible. From the photographs of the polar bears it was obvious that the bear did not always use each joint separately, but sometimes used two at once to give the impression of one. This had been causing me some confusion in my design of the bear, but with a closer inspection of the skeleton I was able to make a far more accurate model that bent in all the right places.
Aside from the basic structure of the model I wanted to add some additional
wobble to the belly and neck. Being as polar bears have a thick layer of
fat and fur to protect them from the cold of the Arctic, they have a secondary
wobble to their movement around these areas when they move. To recreate
this I divided up the blocks that were representing the torso and neck
into 4 pieces so that they could twist horizontally along the backbone
up to the head, but also sway underneath. I added bones into these places
so that I could control this movement.
I made one of the blocks for the belly wobble bigger than the other
as most of the more violent vibrations occurred at the bottom of the belly.
The blocks for the neck wobble were more equal in size than the stomach
blocks, as the wobble down the neck tended to be more of a twisting motion,
which similar sized blocks could represent.
At the head of my polar bear I added bones in the jaw so that the bear could open and close its mouth. Although this would not be a huge part of the animations, a little mouth movement would make the bear seem more real, even if the movement was not noticed by the viewer. Once I had made the body parts and decided where to put the bones inside, I decided that I wanted the legs to be controlled by inverse kinematics so that the paws would remain on the floor as much as possible. As I also wanted the shoulders and behind of the bear to slide past each other as it moved, so I decided to attach an IK handle from the shoulder blade or pelvis to the top of the legs, and another from the top of the legs down to the ankles. This would give me the effect of the shoulder blade and behind moving as well as allowing the legs to bend. I made sure the legs bent in the correct direction for the bear, which was achieved by biasing the bones in the desired direction. I did not want to limit the bones to only move in that direction, however, as I wanted the bear to be as flexible as possible for the positions I wanted it to get into. The ankles were connected with the IK handles in the same way. As polar
bears have very flexible paws and ankles I did not want them to be constrained
as a human ankle might be. F I had at first limited the heel of the paws so that they moved in a similar way to human feet, but on closer inspection of the photographs of the polar bears in various positions, it was clear that the bears do not have the same constraints on the heel. In fact the heel of the front paws bear more of a joint resemblance to a human elbow where it can lay flat on the ground (as a human would do if crawling using the elbows as well as the hands for support), but also raise up onto the front of the paw (as a human would raise up to the hands).
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