Why is the light transmittance of AR head display as important as FOV?

Previously, in a paper, optical display expert Karl Guttag once put forward that “AR is different from VR, and it is not necessary to pursue a large field angle”. He thinks that the visible range of the user’s afterlight is also important to improve the visual experience. Because the residual light of the human eye is sensitive enough to the surrounding movement, in order to ensure the safety of users, this part of the area needs to avoid occlusion as far as possible. < p > < p > Guttag pointed out that for VR, it is more dependent on large field angle and large display area because of its opacity. For AR, even if the FOV is small, the user’s vision will not be blocked much and the surrounding environment can be seen. For example, Google glass’s FOV is only 15 degrees, but its light transmission area can reach 220 degrees except for the part covered by the leg and prism. < / P > < p > of course, not all AR head displays / glasses have the same light transmission range. For example, the field of view angle difference between magic leap one and hololens 2 is not very large, but the light transmission range is quite different, which is due to the different design of the two head display: hololens The upper frame, sensor and MEMS optical module only block the upper vision of the human eye, while the lower hood has high transparency and adopts an open design, which is far away from the human eye and does not block your residual light. < / P > < p > in contrast, magic leap one uses all inclusive frames, and due to its shorter suitable eye distance and closer to the user’s face, the left and right sides of the user’s eyes are basically blocked, and only their feet and ground can be seen from below. < / P > < p > therefore, although magic leap is an MR head display that can reveal the surrounding environment, if it is to be used 24 hours a day, it may not be able to fully ensure the security of users during the mobile process. And low light transmission, but also give people a sense of narrow vision. < / P > < p > and considering that the definition of AR itself is just adding digital content in the real environment, if the AR head obscures most of the user’s vision, is it more like VR and deviates from the true color of ar? < / P > < p > in addition, Guttag also pointed out that magic leap one only emits 15% of ambient light, and the surrounding environment can be viewed through only six layers of diffractive optical waveguides. The experience is not as good as that of a high transmittance hood, and many distortion and distortion of image quality will be seen. However, hololens has only 60% shading and better transmittance. < / P > < p > of course, in addition to magic leap one, many ar head display / glasses on the market also use all inclusive frames, which do not have the wide vision of hololens 2 below the line of sight. Fortunately, they are rarely as close to the user’s face as magic leap one, so the outside of the lens frame can also reveal the surrounding environment. In order to verify the importance of light transmission and residual light vision of AR head display / glasses, it is necessary to understand the activity law of human eyes. Some studies have shown that although the horizontal FOV of human eyes is more than 220 degrees, the range of binocular activity is usually only 120 degrees, and the stereoscopic vision range of left and right eyes is only about ± 40 degrees. In addition, the visual range of the horizontal line of sight was less than 15 ° when FOV was less than 20 ° in the horizontal direction. However, Guttag suggested that the position of the head might affect the visual acuity when the eyes relaxed. A lot of studies have come to the same conclusion because they’re thinking about people at work, with their heads down 15 degrees when they look at a fixed computer screen, he says. < / P > < p > that is to say, when the human eye is relaxed, the line of sight may not be 15 ° below the horizontal line. Therefore, if the fixed computer screen is replaced by head display, the screen that the human eye sees will move along with the head, so the actual relaxing line of sight may be different. < / P > < p > as for the occlusion of hololens 2 for the line of sight upward from the horizontal line, Guttag believes that because of the structure of the face, the eyelid and forehead block the eyeball and can not see the top of the head. Therefore, even if hololens 2 blocks the upper vision, it will not cause too much visual occlusion, and users only need to look up to see it. < / P > < p > finally, Guttag believes that the designers of AR head display gradually deviate from the nature of AR, and the AR head display that blocks the residual light is not only difficult for users to wear while walking. For industrial scenes with high safety requirements, the worse the transmittance, the lower the safety, and it is difficult to apply to workers working all day. Moreover, if the AR head obviously blocks most of the real environment, then AR is not regarded as augmented reality, but more likely to replace reality. If you just want to keep some environment light for some game scenes, you might as well choose perspective AR of pass through class. Continue ReadingVideo Number assistant internal test online! Four functions let you send 1g video on the computer