The ZED X One GMSL2 camera allows the creation of configurable Stereo Rigs with custom baselines, the distance between the optical centers of two cameras.
Selecting the value of the baseline depends on the final requirements and the optics configuration of the two cameras.
In the following scheme, the baseline is identified by B, the minimum depth range is h, and α is the field of view of the cameras for the rectified images.
The values of the field of view of the ZED X Mono cameras in the different optics configurations are available on this support page.
For a fixed minimum depth value h, you can calculate the required baseline B as:
B = (2 * h * tan(α/2))
vice-versa, if you fix the baseline B, the correspondent minimum depth value h is:
h = (B / (2 * tan(α/2)))
To obtain a value of the minimum depth that allows to obtain a usable depth map it is required to apply a "6x" factor to h. This is required to guarantee that the field of view of the two cameras has a good overlapping area:
h' = 6*h ; B' = B/6
The maximum depth (in meters) can be calculated with the formula:
max_depth = (B/2) * F/sens_w * res_W
where
- B is the baseline in meters
- F is the focal length of the optics in meters (2.2 mm, 4mm, or 3 mm according to the camera configuration)
- sens_w is the size of the CMOS sensor in meters (5.8 mm for Global Shutter CMOS, 7.7 mm for the 4K HDR CMOS)
- res_W is the image resolution (you can use 1280 as a good approximation)
How to choose the right sensor?
The global shutter sensor is best for fast-moving objects (or a fast-moving camera) and applications that require accurate motion reproduction.
The rolling shutter 4K HDR sensor is best for low-light environments and for high-resolution HDR images.
How to choose between narrow or wide FOV lenses?
When choosing lenses for your vision system, you should consider the specific requirements of your application as their field of view will have a direct impact on the system's performance. For tasks that involve close-range object detection, narrow FOV lenses are preferable as they provide greater detail. Narrow FOV lenses are also well-suited for long-range detection.
Wide FOV lenses are best for applications requiring broader coverage.
How to choose the baseline?
The baseline of the stereo system depends on the depth perception capabilities needed. A larger baseline enhances depth resolution but imposes limitations on the minimum distance for accurate depth estimation. The tabs below provide an estimate of the accuracy for a variety of distances depending on the baseline and the lens option.
Accessories
In the StereoLabs store, you can find an aluminum bar mount to be used to create precise dual ZED X One stereo rigs with a customizable baseline from 52 mm to 222 mm.
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