I'm working with some MODIS satellite imagery. MODIS data includes a
quality flag mask. For the particular dataset I'm working with, this is
a two dimensional unsigned 16 bit integer array. The quality flags are
stored as one or more bits in each integer value:
Bits are numbered from 0 (least significant bit)
Bit Long name Key
0-1 MODLAND_QA
00=VI produced, good quality
01=VI produced, but check other QA
10=Pixel produced, but most probably
cloudy
11=Pixel not produced due to other
reasons
than clouds
2-5 VI usefulness
0000=Highest quality
0001=Lower quality
0010=Decreasing quality
0100=Decreasing quality
1000=Decreasing quality
1001=Decreasing quality
1010=Decreasing quality
1100=Lowest quality
1101=Quality so low that it is not
useful
1110=L1B data faulty
1111=Not useful for any other reason/not
processed
...<SNIP>...
15 Possible shadow
0=No
1=Yes
Some typical values are:
arr=numpy.array([51199,37013,36885,36889,34841,2062,34837,2061,35033,349
61,2185,37013,36885,2185,4109,4233], dtype=numpy.uint16)
How would I extract groups of/individual bit values from such an array?
Regards
Luke Pinner
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