South Lake Tahoe Caldor Fire Timelapse

Friday, September 3, 2021 

Sentinalhub Playground is an excellent resource for near real time, albeit not quite google earth 1m resolution, satellite images.  One of the cool features is being able to adjust the mapping of the satellite bands to RGB outputs.  For example, using Sentinel-2 L2A image data of South Lake Tahoe between 2021-08-17 and 2021-09-01 and remapping the 2190nm (SWIR2) to red, which tends to highlight fires though isn’t thermal, 783nm to green, a vegetation band (though it is NIR to humans) to make vegetation cover more obvious, and 443nm to blue instead of 490nm as shorter wavelengths tend to be scattered more by aerosols and smoke the fire line (bright red) and smoke (obvs) is very visible while vegetation is (false) green. Burnt earth shows as dark red, compared to bare ground, which tends to show tan in this mapping, thus revealing the current line of fire, the recently burned areas, and the wind direction carrying smoke, which tends to correlate with the advancing line, and fuel (vegetation) still standing.

Sentinel-2 L2A image on 2021-09-01 if South Lake Tahoe Caldor Fire


Then using the history controller to generate and save a sequence of stills, we can animate the progress of the fire with a simple FFMPEG command:

ffmpeg -framerate 1 -pattern_type glob -i '*.jpg' -vf crop=1754:1146 -c:v libx264 -r 30 -pix_fmt yuv420p fire.mp4

and you get:


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Posted at 08:17:00 GMT-0700

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