How to convert between HFOV, FL and Sensor Width for Drone mapping and Inspections
Updated: May 10, 2022
So let's start with the basics, what do the abbreviations HFOV, FL and Sensor width actually mean and why are they important to you as a drone operator?
First let's break those three terms down to give you a better understanding of what they mean.
Horizontal Field of View, this can also be described as the central field of vision for the camera or in easier terms what you see through the lens or on the controller screen as a drone operator.
Focal length can be thought of as the angle of view of a lens. That is, how much of the target scene does the lens capture and how large do objects appear within the frame? Lenses with short focal lengths take in a much wider angle of view and vice versa. In a previous blog we explain the difference between true focal length and the 35mm equivalent
Sensor width is also known as sensor size and determines how much light it uses to create the image. The larger the sensor the bigger the image, or the more megapixels it's capable of. The bigger the image, the better the quality.
Thats the fundamentals of the three, HFOV, FL and Sensor size. So what do they mean to a Drone Operator and why are they so important?
So, why do they matter to you as a Drone Operator........?
Camera manufacturers rarely publish all three parameters relating to their cameras
Our goal here is to help you understand how to convert between HFOV, FL and Sensor Width. These conversions are quite important for modern drone mapping and inspection, as camera manufacturers rarely publish all three parameters for their cameras.
Below we have listed some formulas to help you calculate the variations dependant on the information you have been provided from you camera manufacturer.
Sensor Width Calculation
Sensor Width = 2 *(Focal length *tan (0.5*HFOV / 57.296))
Horizontal Field of View Calculation
HFOV = (2 * arctan (Sensor Width / 2* FocalLength)) *57.296
Focal length Calculation
Focal length = 0.5 * Sensor Width / tan (0.5*HFOV/57.296)
The diagram below explains the concept in a visual format
We understand that these look confusing so here at Hammer, we have created our own comprehensive spreadsheet for calculating formulas specifically for mapping and inspection using the Hammer Platform. Please find the link below:
Get your free and comprehensive spreadsheet designed with Drone Mapping and Inspection formulas over here
We hope this short guide helps you understand how to convert HFOV, Focal Length and Sensor Size and gives a little insight into the importance of being able to calculate the variations for your project. If you'd like to learn more about how to high-quality data and get the most out of your drone missions, please feel free to visit our learning resources.
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— The Hammer Team