In this case, the legs and arms looks short when they are go straight down
but it change quick when they moving
how to design with it? just rigging itself or make longer image and make it turn down to looks short?
or good tutorial for high-angled shot animation?
What approach is better to making animation about High-angle shot character
I think it's mostly based on your art. Art from this angle should be straightforward to rig. Perspective changes are always pretty limited. If you have large perspective changes, then you often need different art. You can often use the same bones, sometimes more or different bones are needed.
I would start by making first doing the rigging that meets your needs for the perspective. See how far you can take that and if it doesn't cover the movement, poses, or other perspectives you need then add new art and possibly more bones to handle that.
rmx I recently rigged some art that has a perspective on the limbs similar to this. I recommend having either an extended version of the arm or both short and long if you want the standing pose to look really good.
The technique is called "Missing link" because ti makes you skip a bone in favor of a bone on the tip so it's more intuitive to translate a piece rather than rotate it:
A similar approach is also used in this blog post:
https://esotericsoftware.com/blog/Rigging-new-poses-tutorial
Hope it helps!