Success in High-speed Shape Measurement under Direct Sunlight Using Pattern Projection

– Achieved by image processing for removing ambient light as noise –

Researchers: Yutaka Satoh, Leader, and Ryusuke Sagawa, Associate Manager for Industrial Science and Technology Program, the Intelligent Systems Research Institute


The researchers have developed a method for measuring the shape of an object that moves/deforms at high speed by accurately detecting a pattern projected on the object using a light source, even in an environment with strong ambient light.

Shape measurement under direct sunlight based on the developed method

Conceptual diagram of noise removal introduced from wireless communication technology


Currently, the use of robots in industry and social life requires sensing technologies that can input the real world as computer data. For example, a shape measurement technology is necessary for a robot arm to hold an object. A pattern projection method is one of shape measurement technologies. By observing the projected pattern, a three-dimensional shape can be accurately measured in a contactless manner. However, under the presence of strong ambient light such as sunlight, other than a pattern light source, the pattern is hidden in the ambient light, and appropriate image processing cannot be performed.

Developed method

Applying the technology for removing noise by converting a signal in a narrow frequency range to that in a wide frequency range, which is used in wireless communication devices such as mobile phones, the researchers have developed a technology capable of removing the effect of ambient light, even when that light is overwhelmingly stronger than the pattern light source. They have also developed a technology to filter a change in brightness slower than the blinking of the pattern light, such as the fluctuation of ambient light and the motion of the object under observation, thus making it possible to observe the shape of an object whose shape changes at high speed. It is thought that this will also be effective for measuring the shape of melting metal and other such purposes, which have been difficult in the past.

Future plan

The researchers will apply the developed shape measurement method to objects under various environments, such as light-emitting objects and objects under direct sunlight, which no existing shape measurement methods based on pattern projection have been able to measure. They aim at the practical use of a technology based on the developed method within several years.

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