<div dir="ltr">Hi Resmi-C,<div>We have a new cover each 16-day from Landsat 8. But I only want one cover in result of my query. I had add new column 'date_of_data' to store date of a raster. And I think range could solve my problem.</div>
<div>Thank you!</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, Mar 19, 2014 at 4:16 PM, Rémi Cura <span dir="ltr"><<a href="mailto:remi.cura@gmail.com" target="_blank">remi.cura@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div><div><div><div><div><div><div><div><div>It is a little bit hard to understand what you mean..<br>
</div>As a summary :<br></div>_you have lot's of rasters. <br>_Each one as a position (and a date associated?).<br>
<br></div>You need to get a raster based on its position (where st_intersects(..))),<br></div>but it is not sufficient and you would like too also filter by date.<br><br></div>You can do so easily by adding a condition in the WHERE, like <br>
</div>AND my_date < .... AND my_date > ... <br></div>(or using time_range <a href="http://www.postgresql.org/docs/9.2/static/rangetypes.html" target="_blank">http://www.postgresql.org/docs/9.2/static/rangetypes.html</a> , if postgres version >= 9.2)<br>
<br></div>Now about making a table per day, it is entirely another question. logically wise, you could get the strict equivalent by adding a column on your raster table with the day of acquisition (the real date would be better).<br>
<br></div>Now deciding to split or not your big raster table into several smaller is more about performance, and should be carefully designed (<a href="http://www.postgresql.org/docs/9.3/static/ddl-partitioning.html" target="_blank">http://www.postgresql.org/docs/9.3/static/ddl-partitioning.html</a>), based on row number, index size, your memory size, how the table will grow, what kind of usage you make of it, and so on.<br>
<br><br></div>Cheers,<br>Rémi-C<br><div><div><div><div><div><div><div><div><br></div></div></div></div></div></div></div></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">2014-03-19 8:28 GMT+01:00 Jackie Nguyen <span dir="ltr"><<a href="mailto:justaniceguy.nguyen@gmail.com" target="_blank">justaniceguy.nguyen@gmail.com</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5"><div dir="ltr"><p style="margin:0px 0px 1em;padding:0px;border:0px;font-size:14px;vertical-align:baseline;clear:both;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;line-height:18px;background-color:rgba(248,248,248,0.6)">
Hi PostGIS Users,</p><p style="margin:0px 0px 1em;padding:0px;border:0px;font-size:14px;vertical-align:baseline;clear:both;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;line-height:18px;background-color:rgba(248,248,248,0.6)">
I have a huge dataset of raster in PostGIS. Each scene is divided into tiles (tile-size 500x500). I was trying to <code style="margin:0px;padding:1px 5px;border:0px;vertical-align:baseline;font-family:Consolas,Menlo,Monaco,'Lucida Console','Liberation Mono','DejaVu Sans Mono','Bitstream Vera Sans Mono','Courier New',monospace,serif;color:rgb(34,34,34);background-color:rgb(238,238,238);white-space:pre-wrap">SELECT rast FROM landsat8 WHERE ST_Intersects(rast, polygon)</code>. It runs very slow, because it returns longitudinal scenes of raster. Where I just want one day's scene.<br>
But the problem is if I query with fixed date, adjacent scene with different date won't be selected. That's not true.<br>So I think about some solutions:</p><ul style="margin:0px 0px 1em 30px;padding:0px;border:0px;font-size:14px;vertical-align:baseline;list-style-position:initial;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;line-height:18px;background-color:rgba(248,248,248,0.6)">
<li style="margin:0px 0px 7px;padding:0px;border:0px;vertical-align:baseline;line-height:16px;word-wrap:break-word">Because Landsat 8 re-visiting every 16 days, so I will insert every 16 days into different table. So I can query from raster that cover all the earth without duplicate.</li>
<li style="margin:0px 0px 7px;padding:0px;border:0px;vertical-align:baseline;line-height:16px;word-wrap:break-word">I'm not sure about ST_Within(), ST_DWithin() then SELECT rast that doesn't overlap other >50%</li>
</ul><p style="margin:0px 0px 1em;padding:0px;border:0px;font-size:14px;vertical-align:baseline;clear:both;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;line-height:18px;background-color:rgba(248,248,248,0.6)">
What would you do in this situation?</p><span><font color="#888888"><div><br></div>-- <br>----<br>Jackie<br>
</font></span></div>
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