Introduction
Maybe you already know that my mobile hard drive is broken and my files can no longer be read. Fortunately, I kept a backup on the PC, but my unmodified mocap animation and unuploaded word file were lost forever.
This is the second time I write a blog about motion capture. I will try my best to restore what I wrote at the time. Perhaps, I will make new discoveries in this attempt.
Process
Motion capture (sometimes referred as mo-cap or mocap, for short) is the process of recording the movement of objects or people.
In filmmaking and video game development, it refers to recording actions of human actors, and using that information to animate digital character models in 2D or 3D computer animation.
When it includes face and fingers or captures subtle expressions, it is often referred to as performance capture.
In many fields, motion capture is sometimes called motion tracking, but in filmmaking and games, motion tracking usually refers more to match moving.
https://en.wikipedia.org/wiki/Motion_capture
I also mentioned the application of this technology in games in my thesis of Design for narrative structure, film language and animation in the first semester. If you are interested, you can read some of my thoughts again:
And this time I am going to practice. In addition to watching Luke’s presentation, I also watched some instructional videos.
https://www.bilibili.com/video/BV1U441167sW
Now I start to practice (again).
If we want to download mocap cilps, we can browse Mixamo, choose our favorite cilps and download fbx files.
I also need to download a character file. To be honest, I can’t find joints in some characters, so I can’t use them. After displaying the bones of the character, we have to make sure that they are T-pose, and if they are not T-pose, we have to adjust it ourselves. Also, don’t forget to check if the character has keyframes.
First, I create definition first, and then assign bones to the right position. In mapping, green represents perfection, yellow represents perfection, and red represents the need for modification. My model does not need to be modified!
Then we have to create custom rigging mapping, which is for the assign controller. Be sure to assign the correct controller. I made a mistake about the hip controller before, which caused me to re-assign my model. Also be careful if assign is wrong, do not press clear all, or it will waste time.
At this time, when we imported our mocap file, I discovered that I also imported the skin, which is wrong. When downloading Mixamo, choose without skin so that only bones can be exported.
This time it was correct. Of course, we also need to check the file, such as whether there are key frames.
As you can see, after I assigned, there are many yellow reminders in the mapping. This is because the bones are not T-pose. I don’t know if this will cause problems, so try it first.
Sure enough, there was a problem with the character and her left hand stopped moving. This requires me to check the mapping. We can see that when we select the effector of the left arm, the controller of the right shoulder is selected, which shows that I assigned the wrong object. 12
In addition, when Maya reminds us The translation attribute on the destination node in the new mapping is locked. How would you like to proceed? We have to choose: Unlock All.
She was still awkward to walk, probably because bone’s initial test state was not T-pose. Let me try another mocap file.
Oh, it still looks strange. I watched Luke’s video again, and I realized the problem: I forgot to give bones assume preferred angle (right click)!
Don’t forget to choose the correct source.
Now my animation is perfect.
I can modify my animation through the anim layer. This is also the mistake I made in the last exercise. For this reason, I contacted Luke and asked him to check it for me. It turned out because I forgot to bake. Because we need to bake the animation information in the definition to the controllers, so that we can adjust the animation through the controllers.
After baking, I arbitrarily added the arm controller to the anim layer and modified it. Sure enough, the animation was changed!
This is my practice! Although there are still some minor difficulties, I have solved them all!
In addition, now I have seen a video about the combination of mocap and metahuman creator in UE5. I believe that what I have learned will definitely come in handy in the future.
Secondly, I can also do some facial expression capture by myself, hope I have time to try it out in the future.
210607 Update
These are what I learned from my collaborative project:
There is a piece of knowledge that I learned during this adjustment! Luke showed how to export our definition, but I exported it and imported it again, but nothing happened. Later I found out that I need to select the bones completely and then import them so that the definition can be perfectly connected to the joints. So I can export and import xml file at will!
The main reason why my animation is not loop animation is because I don’t have switch on in place in mixamo! I really don’t know that this is an option to turn animation into loop animation. Although I regret it, there is no way.
Conclusion
Unfortunately, because of covid-19, we cannot use the school’s mocap equipment. I really hope that I have the opportunity to try this machine: (Anyway, I have done mocap animation so many times (although I have failed many times), I have roughly mastered how to create this type of animation. Because I want to enter the game industry, and mocap will be widely used in 3D games, my exercises can help me. Moreover, using motion capture to observe real movements is also helpful for improving animation skills.