Today’s post will take the bone armature laid out in Episode 3, apply it to our model and pose the model.
Note: I will assume some basic understanding of the tool in these tutorials - if something is unclear let me know in the comments and I will address it
Parenting to armature
Since I have the bone structure in place the next step in the process is parenting the bone to the mesh. What this does is match each bone to a set of vertices in your mesh such that as the bone is moved it also moves the mesh. To do this I first selected by mesh then
Shift-Clicked on the armature so that both are selected. Now that both are selected I pressed
Ctrl-P -> Armature Deform -> With Automatic Weights. Behind the scenes Blender will attempt to map the bones to vertices for you. While a nice feature it’s not 100% accurate which means after parenting the bones I had to go back and adjust the vertex map to make it accurate for the movement of my model.
To see the vertex mappings you can enter
Edit Mode on your mesh and click the
Data tab. In this tab you will see a
Vertex Groups section which shows all the bones you have in your model. If you click on the bone then hit the
Select button below it will select all the vertices that are mapped to that bone.
When I selected the vertex group for the right mandible it also selected a large portion of the head. Since I don’t want the head to move if the mandible moves I was going to have to adjust this and every other vertex group manually. To edit the vertices you can either select the vertices you want then hit the
Assign button next to the
Select button which will assign all selected vertices to that vertex group, or you can deselect vertices you want to keep and with the remaining vertices hit the
Remove button which will remove all selected vertices from that vertex group. Remember to also hit
Deselect as you edit individual vertex groups.
Before I adjusted the vertex groups I wanted to see what it would look like if I moved the bones. Fairly quickly I realized I was lacking proper parenting which was evident by the fact that when I moved the head the mandibles stayed in place. To fix this I went into
Edit Mode on the armature, selected the bone I wanted to fix, clicked on the
Bone tab and set the
Parent value to the proper parent. In this case I set each of the mandible bones so they were children of the head.
After this I adjusted each of parent leg bones so their parents were set to the respective body-part bone.
Now the bones behave as I intended such that moving the main body parts also moved the extremities.
To test out my bone mapping I entered
Pose Mode which can be found in the mode menu when the armature is selected. In this mode you can drag and rotate bones to see how it will affect your model.
Since I knew from my source images that the legs of an ant generally go upward then downward I selected each of the legs and rotated them vertically. To do this uniformly I selected one side of the parent leg bones and hit
RY-70 corresponding to the side of the model which rotates all of the selected bones at the same time.
Adjusting vertex groups
As I began positioning my ant to match the source images I started to see some strange vertex artifacts coming off the body.
I made an assumption that perhaps I did not accurately adjust my vertex groups in the first pass which turned out to be correct. Below you can see from inside one of the main sections of the ant that I was missing a few vertices behind the leg.
Similarly for one of the legs I missed the entire underside of the upper-leg.
Using the adjustment technique outlined above I was able to go back and edit these vertex groups so they were correct. With that done my ant model was looking much better in it’s posed position.
Parent bone location locking
One thing I noticed when moving around the bones was that if I dragged a parent leg bone away from the body it actually moved from the body which was not a desired effect. It turned out I had jumped ahead of the video I was using as a guide from the previous episode and in the section I missed the idea of parent bone locking was outlined. What this does is allow you to restrict the position of a bone such that as you are manipulating it you won’t have to worry about it moving away from the body.
To do this, while in
Pose Mode, I clicked on each of the parent bones, when into the
Bone tab in
Properties section and locked the x, y and z position values in the
Transform Lock section.
With all of the steps here completed I was then able to finish posing my model and creating a temporary plane and material set to at least make it look like a real model.
Since I don’t know all that much about texturing/materials yet I will save legitimate texturing for the future. All in all this was not all that hard to do! I’m looking forward to finding better ways to perform all these steps as some of them seem overly tedious.
- Automatic weighting on bone parenting is great but not perfect - you will have to adjust these mappings manually.
- It’s important to set your bone parents correctly so you can’t move body parts away from others
- Locking the location is also important to prevent weird distortions
Stay tuned for the next episode where I’ll start animating the model!