Dear all,<br>I am trying to use the QA information of MODIS products. I found that this analysis can be done in GRASS with r.bitpattern (from Neteler, 2005 with some <a href="http://wald.intevation.org/tracker/index.php?func=detail&aid=576&group_id=21&atid=207" target="_blank">examples</a>) or with r.mapcalc . <br>
<br>From what I understood, the use of r.mapcal seems to be more flexible. I am just wondering if there are some code examples using the bitwise operators of mapcalc. I <a href="http://www.mail-archive.com/grassuser@grass.itc.it/msg00127.html" target="_blank">found</a> the following code:<br>
<pre>"lst_filt = (lstmap ~ [XX XX XX 00]) || (lstmap ~ [XX XX 0X 01])"<br></pre>but to me it is not really clear how this works, especially compared to the <a href="http://www.mail-archive.com/grassuser@grass.itc.it/msg00004.html" target="_blank">code</a> provided (and explained) by Glynn Clements:<br>
<pre>r.mapcalc MASK="if((sur_refl_qc_250 / 16) % 16 == 11 , 1, null())"<br><br></pre>Thank you very much for any help.<br><br>Laura<br><br><br><br>
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