Markerless Motion Capture for Primate Locomotion Studies

人类的移动方式是独一无二的，因为我们是唯一能够完全直立行走的动物。我们认为这一特征是在人类谱系从黑猩猩谱系中分离出来后不久出现的，因此了解我们是如何移动的将有助于我们理解这种分裂是如何发生的。为了理解人类行走和奔跑的进化，我们还需要知道我们最近的亲戚是如何行走和奔跑的，这导致许多研究人员研究非人类灵长类动物的运动。最常见的方法是简单地使用摄像机拍摄动物的行为。然而，在实践中，这种技术有许多困难。要从视频胶片中进行测量，要么需要我们在研究动物身上放上反射标记，这通常是不可能的，要么需要一个熟练的研究人员单独测量单个帧，估计灵长类动物的关节位置。这不是很准确，因为关节的位置经常被头发遮住。通常我们想要了解在3D中发生了什么，因为灵长类动物在树上花了很多时间，它们的动作非常复杂，这很难通过简单的视频分析来量化。幸运的是，在过去的几年里，计算机技术已经发展到这样一种程度，我们可以从一系列照片中重建三维形状，只要它们重叠。这种立体重建的工作原理是通过识别共同特征来实现的，就像我们眼睛的立体视觉一样。有了高清视频，就有可能在3D中提取被测动物的皮肤轮廓。这只是战斗的一半，因为我们真正想知道的是骨骼是如何在皮肤下运动的。幸运的是，我们也有从CT扫描中获得的精确的骨骼3D模型，可以在皮肤包膜内安装，这应该给我们提供我们需要的信息。这个项目的目的是测试这种新方法的有效性。我们可以将使用新技术获得的结果与使用一系列替代标准技术获得的结果进行比较。通过在控制条件下使用训练有素的猴子作为我们的研究动物，我们甚至可以使用非常精确的基于标记的系统作为“金标准”参考，以确定新技术的局限性。通过在一系列不同的动物身上尝试这项技术，我们可以看到毛发的特征，如毛发长度或颜色，是否会导致任何问题。最终的目标是产生一种更好的技术来研究灵长类动物的运动，这将大大减少所需的努力，同时产生更好的结果。这些改进后的数据对于我们理解现代人类运动方式进化的全部复杂性以及我们与灵长类近亲的区别是必要的。

Humans are unique in the way they move since we are the only animal that is able to walk on fully straight legs. We think that this feature occurred very soon after the human lineage split off from the chimpanzee lineage so that understanding how we came to move the way we do will help us understand how this split occurred. To understand the evolution of human walking and running we need to also know about how our nearest relatives walk and run and that has led to many researchers studying non-human primate locomotion. The commonest approach is simply to use a video camera and film what the animal is doing. However in practice there are many difficulties with this technique. To take measurements from video film either requires us to put reflective markers on the study animal which is usually simply not possible, or the individual frames need be measured individually by a skilled researcher estimating where the primate's joints are. This is not very accurate because often the joint positions are obscured by hair. Often we want to understand what is happening in 3D since primates spend a lot of time in the trees and their movements are very complex and this is particularly difficult to quantify from simple video analysis. Fortunately in the last few years computer technology has advanced to such an extent that we can reconstruct three-dimensional shape from a series of photographs as long as they overlap. This stereo reconstruction works by identifying common features in much the same way that the stereoscopic vision works in our eyes. With high definition video it is therefore possible to extract the skin outline of a subject animal in 3D. This is only half the battle since what we really want to know is how the skeleton is moving underneath the skin. Fortunately we also have accurate 3D models of the skeleton obtained from CT scans that can be fitted within the skin envelope and this should give us the information we require. The purpose of this project is to test the effectiveness of this new approach. We can compare the results we obtain using the new technique against those we obtain using a range of alternative standard techniques. By using trained monkeys in controlled conditions as our study animals we can even use the very accurate marker based systems as a 'gold-standard' reference to identify what the limitations of the new technique are, and by trying the technique on a range of different animals we can see whether features of the fur such as hair-length or colour cause any problems. The ultimate goal is to produce a much better technique for studying primate locomotion that will greatly reduce the effort required whilst at the same time producing better results. This improved data is necessary to allow us to understand the full complexity of the evolution of the way modern humans move and how we differ from our nearest relatives among the primates.