<br><font size=2 face="sans-serif">Okay - unfortunately i am now totally
confused. I have tried to read up on binary data (to little or no avail!!!).
My understanding is the MODIS suf_refl_qc data that i have import is a
unsigned 16 bit integer number. I would like to select out pixels using
this raster to create a cloud mask based on some of the bit codes.</font><br><br><font size=2 face="sans-serif">for example identify " band 1 quality
= missing input" would have the following </font><br><br><font size=2 face="sans-serif"> * * * * 1 0 1 1 * * * * * * *
* * - where * represents placeholder</font><br><br><font size=2 face="sans-serif">If i try and follow Glynn's logic he
is saying divide the number by 16 and then take the modulus 16 and then
equate it to "11" to get the subset. </font><br><br><font size=2 face="sans-serif">I am unsure how I choose the "11"
and how do i change the syntax to pull out the different masks i may be
interested in.</font><br><br><font size=2 face="sans-serif">0 0 * * * * * * * * * * * * * *
ideal quality all bands</font><br><font size=2 face="sans-serif">0 1 * * * * * * * * * * * * * * less
than ideal quality</font><br><font size=2 face="sans-serif">* * 0 0 * * * * * * * * * * * * clear</font><br><font size=2 face="sans-serif">* * 0 1 * * * * * * * * * * * * cloudy</font><br><font size=2 face="sans-serif">* * 1 0 * * * * * * * * * * * * mixed</font><br><font size=2 face="sans-serif">* * * * 0 0 0 0* * * * * * * * highest
quality band 1</font><br><font size=2 face="sans-serif">* * * * * * * * * 0 0 0 0* * * highest
quality band 2</font><br><font size=2 face="sans-serif">etc...</font><br><br><font size=2 face="sans-serif">Any help would be greatly appreciated.
At this stage im plugging in the decimal numbers into binary calculator
and using r.reclass to create a MASK.</font><br><br><font size=2 face="sans-serif">best regards</font><br><br><font size=2 face="sans-serif">Andrew</font><br><font size=2 face="sans-serif"><br></font><br><br><font size=2 face="sans-serif"><br></font><br><br><br><table width=100%><tr valign=top><td width=40%><font size=1 face="sans-serif"><b>Glynn Clements <glynn@gclements.plus.com></b></font><br><font size=1 face="sans-serif">Sent by: grassuser-bounces@grass.itc.it</font><p><font size=1 face="sans-serif">05/28/2007 09:14 AM</font><td width=59%><table width=100%><tr><td><div align=right><font size=1 face="sans-serif">To</font></div><td valign=top><font size=1 face="sans-serif">Hamish <hamish_nospam@yahoo.com></font><tr><td><div align=right><font size=1 face="sans-serif">cc</font></div><td valign=top><font size=1 face="sans-serif">grassuser@grass.itc.it</font><tr><td><div align=right><font size=1 face="sans-serif">Subject</font></div><td valign=top><font size=1 face="sans-serif">Re: [GRASS-user] help to
use r.mapcalc with decimal/binary (modis data)</font></table><br><table><tr valign=top><td><td></table><br></table><br><br><br><font size=2><tt><br>Hamish wrote:<br><br>> > Oops; I could have sworn that r.mapcalc understood hex. Sorry;
you'll<br>> > need to use decimal values, e.g.<br>> > <br>> > r.mapcalc MASK="if(sur_refl_qc_250 & 240 == 176 , 1,
null())"<br>> <br>> so r.mapcalc can do bitwise & |? (nothing about that in the help
pages)<br><br>Damn, no, that neither.<br><br>Third attempt:<br><br>
r.mapcalc MASK="if((sur_refl_qc_250 / 16) % 16 == 11 , 1, null())"<br><br>I'll look at adding the missing functionality to r.mapcalc.<br><br>-- <br>Glynn Clements <glynn@gclements.plus.com><br><br>_______________________________________________<br>grassuser mailing list<br>grassuser@grass.itc.it<br>http://grass.itc.it/mailman/listinfo/grassuser<br></tt></font><br><BR>
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