I have an upcoming project of an aerial photogrammetry survey with NADIR images.
It is an oil industry plant that is under operation.
The requirement is to achieve 1:200 scale accuracy.
As per my calculations using formulas from your knowledge base, in order to achieve this accuracy with the GoPro Silver Hero 3+ the flight height should be at around 30 meters.
Since there are several chimneys under operation I prefer to raise my flight height up to 100 or even 150 meters. This will guarantee my UAV will never hit anything.
However, while increasing the flight height my GSD and consequently accuracy is reducing.
Can I use a magnifying lens so that although my UAV will fly at 150 meters, the ground will appear optically closer and photos will be taken as if the UAV flew at 50 meters?
Is there a recommended set of LENS (mm) vs Flight Height?