This class has been tasked with designing, constructing and launching a remote sensing platform into near space and finding applications for the imagery acquired. The project is continually evolving and this blog will be a forum to publish our progress.


Image Footprint Calculations

We want to make sure that we have an appropriate focal length for capturing our area of interest. We’ve worked out some calculations of the camera’s image ‘footprint’ at various focal lengths and altitudes. Our likely focal length will be between 30-35mm. The graph above shows the footprint or coverage area at various altitudes with a 34mm focal length. There is a polynomial relationship between altitude and image footprint in meters2

The equation for this relationship is: Y=0.1954x2 + 1.0421x - 7149.7 

Y= footprint in meters2 x= altitude in meters

For example, according to this relationship, at 20,000 meters in altitude, we will have a footprint of 78173692 meters2 (or 30.18 miles squared).  This relationship was derived using a formula for angle of view ( theta = 2 arctan (d/2f), where f=focal length and d= size of focal plane) and then the formula for one dimensional swath width ( swath width = 2(H tan (theta/2)).
- ryan callihan - camera team

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