[HN Gopher] How to Make a Photo Trap with a Raspberry Pi and a S...
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       How to Make a Photo Trap with a Raspberry Pi and a Sony Alpha
        
       Author : lukastyrychtr
       Score  : 24 points
       Date   : 2021-03-25 16:29 UTC (6 hours ago)
        
 (HTM) web link (petapixel.com)
 (TXT) w3m dump (petapixel.com)
        
       | morsch wrote:
       | The way he triggers the photo is rather clever:
       | 
       |  _Instead of actually recognizing any feature in the image, the
       | script just determines how much of the image is in focus. ... the
       | script calculates this measure for "focus" for each frame of the
       | preview video and takes a gliding average of this value for over
       | a minute. The value changes and drifts slightly as lighting
       | changes over the day and this average will keep track of the
       | current "base" focus of the empty scene. But when a squirrel
       | enters the frame and occupies the area that is otherwise out of
       | focus, this "focus measure" suddenly increases significantly._
       | 
       | Like most good ideas, it seems obvious in hindsight.
        
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       (page generated 2021-03-25 23:04 UTC)