Then, you can run a separate command to process the non-alpha bands.<br>You need two processes because there may not be one-to-one mapping of the non-alpha and alpha band polygons.<br><br>Finally, you need to make intersections of the polygons in the two layers and store the values of the alpha band polygons. I can't find any scripts that do this. I'm afraid you need to do this yourselves.<br>
<br><div class="gmail_quote">On Tue, Jul 26, 2011 at 9:56 AM, Chaitanya kumar CH <span dir="ltr"><<a href="http://chaitanya.ch">chaitanya.ch</a>@<a href="http://gmail.com">gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
John,<br><br>gdal_polygonize script stores the common pixel value in a field for every polygon. By default it is named 'DN', which can be changed by specifying the fieldname option.<br><br>You must use the alpha channel to polygonize. So you have to use the -b option to specify that and may have to use the -nomask option too.<div>
<div></div><div class="h5"><br>
<br><div class="gmail_quote">On Tue, Jul 26, 2011 at 9:21 AM, jt2000 <span dir="ltr"><<a href="mailto:thakkar@nexgenwireless.com" target="_blank">thakkar@nexgenwireless.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Thanks Jay,<br>
<br>
Ideally I would like the data to be in a column of the shapefile output so I<br>
can load it in the database and use it to query. With gdal_polygonize.py<br>
this doesn't seem possible so I was wondering what other options are out<br>
there.<br>
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</font></blockquote></div><br><br clear="all"><br></div></div><font color="#888888">-- <br>Best regards,<br>Chaitanya kumar CH.<br><br>+91-9494447584<br>17.2416N 80.1426E<br>
</font></blockquote></div><br><br clear="all"><br>-- <br>Best regards,<br>Chaitanya kumar CH.<br><br>+91-9494447584<br>17.2416N 80.1426E<br>