I am trying to understand how does Dronedeploy finds the altitude value for a specific GSD.
For a Mavic Air camera sensor we have the following specifications:
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sensor type: 1/2.3” CMOS
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sensor size: 6,33 x 4,7 mm
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image size:4056 x 3040 pixels
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focal length (f): 35mm
To calculate the pixel size on image (lower case gsd) we can use the sensor size and the image size: gsd = 6,33/4056 = 1,56x10^(-6)m
Now, if i want a GSD = 1,3cm, I can use the following relation:
f/Altitude = gsd/GSD =>
0,035 / Altitude = 1,56x10^(-6) / 0,013
(0,035 * 0,013) / 1,56x10^(-6) = Altitude =>
Altitude = 291,666m
But Dronedeploy specifies an Altitude of 36m for a 1,3cm GSD! Why?