Rigging / Blend Shapes

As my character is a quadruped, I knew the rigging set up would be slightly different so in order to get to grips with this and create a fully working rig, I followed tutorials online which gave me a basis to work from. My previous knowledge of rigging still came into use with mirroring joints and putting in IK spline. I found that researching into a cat's skeleton was really useful as this showed me where to put the joints and also the names. With cats, they have an extra bone on their front legs above what essentially would be the ankle, this allows more movement and flexibility. Because of this set up, the placement of the IK's would be slightly different to how a biped would be, so I added in an extra IK between the joints to allow for this movement. I realised that after I rigged and weight painted the model, I could have done with less joints in the neck as a few of these aren't really needed and it would have been easier to weight paint with a couple less. I originally planned to include joints for the eyebrows as this would allow me more control over this area, however I ended up forgetting to put these in and I would have had to unbind the mesh and do it all over again. Instead I had created blend shapes for the eyebrows, including the main expressions I will need.

Using the component editor was something I came across within the tutorials and found it a really useful tool. By going into component mode you are then able to select certain verts and adjust their influence. This is a more accurate way than just weight painting and allows more control, obviously this should only be used for small areas, areas where it's hard to weight paint or where some adjustments are needed.

When it came to creating the blend shapes I came across a major issue, when using the blend shapes they ended up distorting the mesh in areas that were not modified in any way at all. I was told by my tutor that some way along the line the mesh got distorted from the original one, and seeing as I duplicated the mesh before I bound it every time the blend shape is used, it always wants to go back to how it was, hence the deformations in other areas of the geometry. To try and fix this problem we first unbound the mesh from the rig and exported this out separately, by doing this I then had the original mesh back. I then imported it into the scene I was working on and began to detach all the heads of my blend shapes from the body. Seeing as only the tail and right front foot was affected, I would not have to re-do all the blend shapes again. After this I then re-attached the heads to the new body. At first this seemed like it would work, however in the end the blend shapes became destructive. We found that only a couple were really destructive, so by taking those away and duplicating a blend shape that worked correctly, we used that as the new geometry. This process took longer than I anticipated especially seeing as I had to re-weight paint my character and attach all the controllers again, however it is still better than having a broken character! I have learnt many new things so it wasn't a waste of time, and also by having to re-do certain aspects I understand the process more and am able to do it in a much faster time than before.

Blend Shape Tutorial

I had previously tried out using blend shapes during the summer break so I had a basic understanding of the process. With blend shapes you have to duplicate the master geometry and alter the duplicates by adjusting the vertices. There are many uses for blend shapes, the main one being a deformation, the other use is corrective blend shapes. This is useful to correct certain areas of the geometry, for example when you open your mouth, there are deformations that take place in the cheeks, so by using blend shapes you can put this in place to add more realism. They can also be used to alter any areas that aren't working correctly. You have to make sure that you don't delete the history or freeze the transformations of the duplicates of the geometry, if you do you the blend shapes will revert back to the original place of the master geometry. When selecting the blend shapes, always select them in the order you created them and then the master geometry last. From here you would create the blend shapes and add set driven keys to allow you to animate it.

I will be definitely be using blend shapes when it comes to my character, most likely in the form of expressions, I will have to make a note of all the expressions I want and duplicate the necessary amount of geometry needed.