Science Fiction Films, VR Experiences... We Make Animation Special Effects More Realistic

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2024 Nov. 29

Wang Chao
Associate Researcher and Doctor, Zhejiang Institute of Metrology
Partner Enterprises: Shanghai Chingmu Vision Technology Co., Ltd., Zhejiang Pumai Technology Co., Ltd.

The movement trajectories of limb nodes are captured by reflective target balls.

On August 6, 2021, a phone call came into the length professional office of the Zhejiang Institute of Metrology: "Hello, can you test motion capture equipment?"

I became interested immediately because my work involves precision measurement technology, including three-dimensional spatial positioning and attitude research, and I am also an anime fan. Nowadays, people's pursuit of the fineness of visual enjoyment is getting higher and higher, and motion capture technology is leading the reform trend of the Chinese animation industry.

Motion capture, simply put, is through wearable sensors - usually matte motion capture suits and reflective balls, combined with technologies such as machine vision and laser tracking, to capture the movement trajectories of each flashing point, and then record these movement trajectories in the form of point sources and match them to the skeletal nodes of the corresponding model to realize the movement of the model.

In the film and television industry in the early 21st century, motion capture technology became famous with the release of "Avatar". It can assist artworks in enriching the limb movements of characters and improving the synchronization of scenes, endowing characters with more soulful movements and expressions under the design of animators; it is also more efficient. For a set of consecutive movements of a character, if it depends on traditional hand-drawn animation, it takes one month, while through motion capture technology, it can be compressed to a few hours.

The motion capture technology in "Avatar" adopts facial reflective point recognition to realize character expression interaction.

Currently, many motion capture enterprises with independent intellectual property rights and self-developed products have been established in China, with a cost performance and sales volume leading the world. We had further exchanges with the caller and learned that the Shanghai Chingmu Vision Technology Co., Ltd. where he is located is a well-known motion capture equipment enterprise, which has independently developed multiple motion capture cameras and supporting software algorithms.

Its business involves motion capture, spatial positioning, virtual reality theme parks, virtual simulation, etc., and has launched VR simulation police systems, holographic remote same-screen series interview systems, and has become the VR technology service provider for many enterprises such as Sina, Alibaba, ByteDance, and Huawei.

Since motion capture is an emerging high-tech industry and lacks the guidance of national standards, enterprises face the problem that key parameters cannot be traced to the source, and they cannot confirm the current technical deficiencies. Therefore, our institute was commissioned to evaluate the motion capture products.

The positioning accuracy of the equipment is one of the important evaluation criteria for the leading level of the core technology and product competitiveness of the motion capture system. It refers to the deviation value between the actual spatial position of the reflective target ball and the coordinates of the three-dimensional spatial points of the human model generated by the software. The higher the positioning accuracy of the motion capture equipment, the more outstanding the effects such as the authenticity and smoothness of movements during use.

The spatial point positioning accuracy and motion trajectory analysis technology involved in the motion capture system involve the field of three-dimensional spatial precision measurement, which exactly coincides with the development direction of the Zhejiang Key Laboratory of Digital Precision Measurement Technology, which is also an important reason why we pay attention to and study motion capture technology.

On September 16, we received the technical personnel of Shanghai Chingmu Vision Technology Co., Ltd., had in-depth exchanges on the accuracy verification plan, and then carried out evaluation experiments on the company's MC4000 motion capture camera and supporting software.

Accuracy Detection of the Motion Capture Equipment of Shanghai Chingmu

First, we used the length reference device "one-dimensional long-length measurement system" to make the air-floating platform with the reflective target ball base (a rigid base with multiple reflective target balls) move in a straight line, took the obtained spatial displacement distance as the standard value, and compared it with the moving distance of the reflective target ball base in the software to evaluate the positioning repeatability and relative displacement repeatability of the motion capture equipment.

Then, we used a high-precision standard circular trajectory generator to perform multiple rotation tests on the reflective target ball base, analyzed the spatial angles of the samples through软件, and compared them with the standard rotation values to evaluate the spatial pose accuracy of the motion capture equipment. Based on the above measurement results, we pointed out the subsequent technical improvement directions for the enterprise to improve the long-distance positioning compensation ability.

We also publicized the "Open Laboratory" policy of the Provincial Market Supervision Bureau to the enterprise. This policy opens laboratory equipment, technical standards, scientific research achievements and other scientific and technological resources that meet the conditions to the society in a non-profit manner. Enterprises can carry out quality inspection, R & D testing, standard verification and other activities in the open laboratory to reduce innovation costs. The enterprise engineer said happily: "From now on, we also have a professional testing laboratory."

In addition, our institute has also assisted many motion capture enterprises such as Zhejiang Pumai Technology Co., Ltd. Currently, we are cooperating with the Westlake Laboratory to carry out the standardization work of the accuracy detection of motion capture equipment. The motion capture industry needs more detailed detection standards and technical requirements. Only with high standards can we promote the development of core technologies and enhance the international competitiveness of products.

Through exchanges and cooperation with enterprises related to the motion capture industry, I deeply realize that the service of metrology to society cannot be confined to the traditional manufacturing demand fields.

At present, Zhejiang has set the goal of leading high-quality development with scientific and technological innovation and digital economy. As a scientific researcher of the Market Supervision Bureau, we will actively explore and discover the metrological needs of emerging industries, constantly research new technologies and new solutions, use standards to assist innovation, and help new industries, new products and new markets embark on a development path of high level, high quality and high standards.

Author: Dr. Wang Chao
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