Using Infrared (IR) rays, object image can be captured in 2D and 3D forms. Based on 3D image of the object and distances of the object from the CMOS sensors at various angles, innovative security and automation solutions can be developed. Present day depth sensors are based on the reflected IR rays. Having multiple IR transmitters and CMOS sensors at different angles helps in capturing the shadow of the object on the opposite side of the IR transmitter. Making use of both reflected and shadow IR rays, more accurate 3D image of the object can be obtained.
Block diagram of a simple setup is shown in figure. Here, each IR transceiver consists of a servo-based IR ray projector to project in multiple angles and servo-based CMOS sensor capturing IR images from different angles such as 45/90/135 degrees. Instead of servo, multiple IR ray projectors and CMOS sensors can also be used. While IR transceiver 1 projects IR rays, IR transceiver 1 can capture the reflected IR rays and either or both IR transceiver 2 & 3 can capture the shadow of IR rays at 45 and 135 degree angles respectively.
If only reflected IR rays are used, the error in the distance calculated and 3D image constructed increases as the object is moved far away from the IR transceiver. If an object is closer to IR transceiver 1, its shadow will be larger on the side of IR transceiver 4. Larger shadow can augment the estimation of the distance of the object and hence can keep the overall error approximately same irrespective of the distance of the object as well as can reduce the overall error.
Panoramic 3D image of the object can be created. More the number of IR transceivers, the better quality 3D image is obtained. Multiple diffusers and type of lenses can be used to create different patterns such as pseudo-random. The shape and size of the reflected image indicates the distance of the object. Alternatively, different IR beams and intensity of the IR rays can be useful in determining the distance of the object.
For IR operation, light is not needed. It can work in the presence/absence of sun light, tube/incandescent/LED light, etc. IR rays, which are not visible/disturbance to human eyes, becomes attractive for security and automation (home and industrial) applications. This design offers numerous applications such as gesture application, electrical appliances automation based on the presence of humans, identifying shape/size/type of objects, intruder detection and alarm generation and logging/capturing the events, robotic applications, medical application, gaming application, etc.
The shape and size of the room in which the IR based security and automation solution is installed can be found out by automatic calibration and can be shared among the IR transceivers by wired/wireless means for later computation of algorithm.
While home automation provides luxury, convenience and quality of life, industrial automation improves efficiency/safety, saves time, and reduces production cost. Cost of the IR transmitter and CMOS sensor are low.