Both 3D structured light and ToF sensor solutions are similar to radar detection methods, relying on additional light sources to detect depth of field, and associated hardware for specific processing of this special light source. By not having to deal with complex natural light, these hardware can obtain depth-of-field data more efficiently and accurately, independent of real-world lighting conditions. So what are the advantages of 3D structured light and ToF sensor?
3D structured light itself has many advantages, such as high precision, low power consumption, all-weather, and good environmental adaptability. It is very suitable for face recognition, payment, and supplementary details for selfie beauty. Therefore, after the iPhone X was equipped with this technology, some Android flagships also began to carry this technology.
3D structured light based on the speckle structured light principle emits a diffracted light spot onto the object, and the sensor receives the deformed light spot, so as to judge the depth information according to the amount of the deformation of the light spot. The energy density of the diffracted light spot emitted by it will decrease at a certain distance, so it is not suitable for long-distance depth information acquisition. The working distance range of 3D structured light is very short, only 0.2m-1.2m, which is suitable for the front camera of mobile phones, and the rear camera that requires long-distance information is also not suitable for 3D structured light.
ToF sensor continuously sends optical signals to the measured target, then receives the optical signal returned from the measured target at the sensor end, and then calculates the round-trip flight time of the transmitted and received optical signals to obtain the distance of the measured target. Like 3D structured light, ToF sensor is a technology used to supplement the Z-axis depth information of the image. However, unlike 3D structured light, the ToF sensor emits not speckle, but a surface light source, so within a certain distance, the light information of the ToF sensor will not experience a lot of attenuation, and the unit pixel of the ToF sensor photosensitive element It is very large, 10μm, which is sufficient for light collection. In theory, as long as the power of the transmitter is increased, the ToF sensor can be used very far away. In general, the working distance range of the ToF sensor is 0.4m-5m. Therefore, on the whole, the ToF sensor is more suitable for use on the rear camera.
