How far can I see? This is a question we get quite often at Datatoys. Whether you are wondering if you can see a deer on the runway or capturing the details of a property from the air, this article will help you calculate the exact resolution, altitude, and lens you need.

It has likely been a while since your last math class, so let us run through the basics. In order to calculate the field of view, altitude, and resolution you need you must first select values for two of the three variables. For example to calculate a discrete resolution value the lens and altitude you desire must be known. Here is an example of some of the most common scenarios:

Problem 1: Altitude and Field of View are known, solve for Pixels per Foot.

Altitude Above Ground Level: 1000ft

Field of View: 16 degrees (16mm)

Pixels per Foot/Resolution: Unknown

PPF=360/AGL*TAN(FOV/2)

PPF=360/1000*TAN(FOV/2) Substitute AGL Value

PPF=360/1000*TAN(16/2) Substitute FOV Value

PPF=360/1000*TAN(8) Simplify

PPF=360/1000*(0.141) Simplify, Remember to use degrees

PPF=360/141 Simplify

PPF=2.55 Pixels per foot

Problem 2: Pixels per Foot and Field of View are known, solve for Altitude.

Pixels per Foot/Resolution: 1 Pixel per foot

Field of View: 16 degrees (16mm)

Altitude Above Ground Level: Unknown

AGL=360/PPF*TAN(FOV/2)

AGL=360/1*TAN(FOV/2) Substitute PPF Value

AGL=360/1*TAN(16/2) Substitute FOV Value

AGL=360/1*TAN(8) Simplify

AGL=360/1*(0.141) Simplify, Remember to use degrees

AGL=360/(0.141) Simplify

AGL=2553ft

Problem 3: Pixels per Foot and Altitude are known, solve for Field of View.

Pixels per Foot/Resolution: 1 Pixel per foot

Altitude Above Ground Level: 1000ft

Field of View: Unknown

FOV=(arctan(360/PPF*AGL))*2

FOV=(arctan(360/1*AGL))*2 Substitute PPF Value

FOV=(arctan(360/1*1000))*2 Substitute AGL Value

FOV=(arctan(360/1000))*2 Simplify

FOV=(arctan(0.36))*2 Simplify

FOV=(19.8 degrees)*2 Simplify, Remember to use Degrees

FOV=39.6 degrees

*When using the Helios substitute “360” with “160”, FOV is fixed at 36 degrees.

* Datatoys lenses are measured in diagonal field of view; the equations require a horizontal field of view. Please see the chart below for values.