Table of Contents
What is field of view?
The Field of view (FoV) refers to the largest area on its sensor that a camera can capture a scene or object. It is determined by the focal length of the lens and the size of the sensor. A longer lens or smaller sensor produces a narrower field of view, while a shorter lens or larger sensor produces a wider field of view. According to the direction of FoV, the FoV angle can be divided into the following three categories: H FoV—Horizontal Field of View; V FoV—Vertical Field of View; D HoV—Diagonal Field of View. As shown in the diagram below:
Assuming that the width of the sensor image region is W, the height is H, and the focal length is f, then each field Angle is f calculated as follows.
What is angular resolution?
Angular resolution refers to the minimum angle between two adjacent pixels. Angular resolution is typically expressed in Pixels Per Degree (PPD). PPD represents the number of pixels within each degree of the field of view. The higher the PPD value, the finer the details displayed and the higher the visual clarity. The more pixels in the same FoV, the higher the angular resolution. Using the same optics at the same distance, more pixels can provide a larger FoV.
Calculate the horizontal and vertical angular resolution separately:
How to calculate FoV coverage area of Time-of-Flight (ToF)?
The coverage area in the vertical direction can be calculated given that the V FoV angle is α and the distance d from the ToF camera to the target.
In the same way, the H FoV angle is β assumed to be the coverage area of horizontal direction is:
How to calculate X, Y resolution of ToF?
The calculation formulas for the X and Y resolution of ToF camera are as follows:
For example:
The resolution of the ToF camera is 640×480, the FoV angles of ToF are, respectively H FoV = 70°,V FoV = 50°, calculating the X,Y resolution of the ToF camera when the object is placed at 1m:
The coverage area is calculated in the first step:
The second step computes the size of X, Y in ToF:
The corresponding resolutions at other distances of object placement are as follows:
| Distance | Horizontal coverage(m) | Vertical coverage(m) | X(mm) | Y(mm) |
| 2m | 2.8008 | 1.8652 | 4.3763 | 3.8858 |
| 3m | 4.2012 | 2.7978 | 6.5644 | 5.8288 |
| 4m | 5.6016 | 3.7304 | 8.7525 | 7.7717 |
| 5m | 7.002 | 4.663 | 10.9406 | 9.7146 |
