Popular Types of Consumer-Level Cameras¶
Monocular Vision cameras¶
A monocular vision camera is a camera used for a single eye. The optical route of such cameras may have a series of lenses, but it has only one vision. Most of the cameras on the market are monocular vision cameras, including various types of webcams, single-lens reflex (SLR) cameras, and industrial cameras, etc. Monocular cameras have limited depth perception. The following picture shows a typical monocular vision SLR camera ( cited from Wikipedia SLR ).
Binocular Vision cameras¶
A binocular vision camera (stereo camera) is a camera used for two eyes that a lot of animals have. It helps to build up the depth perception by calculating binocular disparity. All state-of-the-art cellphones now come with dual back cameras, such as Xiaomi Pocophone F1 (cited from Wikipedia Stereo_camera).
RGB-D Cameras¶
As one of the most popular RGB-D sensors, Kinect was firstly launched by Microsoft in November 2010. Just as its name implies, RGB-D sensors are particular sensors which
not only sense the RGB colors
but also have depth perception
RGB-D sensors have active light source (therefore, a stereo camera is not regarded as a RGB-D camera), and are normally categoried in three types according to three different technologies:
Structured light sensors based on dense gray code, etc. – normally for industrial applications, such as 3D scanners
Structured light sensors based on sparse speckle pattern – normally for consumer-level applications, such as Intel Realsense, etc.
No matter which technology in the above is utilized, a RGB-D sensor share similar components:
An RGB sensor
A depth sensor composed of a pair of IR emitter and receiver
Both RGB sensor and depth sensor need to be well-calibrated for the alignment of both RGB image and depth image
Some popular structured light RGB-D sensors based on sparse speckle patterns are enumerated as follows (all pictured are cited from their respective official websites):
What’s more, Kinect 2 changes its core technology from structured light to TOF, and the parameters and its price/performance ratio stands out among all TOF sensors. Kinect 2 sensor looks as (cited from SlideShare: Programming with kinect v2):
In the following sections, we’re going to discuss how to calibrate:
monocular vision cameras with narrow-angle lens
monocular vision cameras with fisheye lens
binocular vision Cameras
RGB-D cameras
step by step.