<div dir="ltr">For the record :<div>when outputting the image to disk then loading it into postgis, image shows fine (band 1 and band2)</div><div><br></div><div>When 'add canvas' on the image in QGIS, a nex layer is created, but empty.</div>
<div><br></div><div>Do you know other way to do it?</div><div><br></div><div>Cheers,</div><div><br>Rémi-C</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">2013/12/19 Rémi Cura <span dir="ltr"><<a href="mailto:remi.cura@gmail.com" target="_blank">remi.cura@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">QGis 2.0.1.<div>I tried as well to convert to UINT16</div><div>no sucess</div></div><div class="HOEnZb">
<div class="h5"><div class="gmail_extra"><br><br><div class="gmail_quote">2013/12/19 Rémi Cura <span dir="ltr"><<a href="mailto:remi.cura@gmail.com" target="_blank">remi.cura@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Is there a special trick to display the raster in QGIS?<div>I do </div><div>db manage/right click on the raster table/add to canvas</div>
<div>Seems like there is nothing in it afterward.</div><div><br></div>
<div>Thanks again,</div><div><br></div><div>Rémi-C</div></div><div><div><div class="gmail_extra"><br><br><div class="gmail_quote">2013/12/19 Rémi Cura <span dir="ltr"><<a href="mailto:remi.cura@gmail.com" target="_blank">remi.cura@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Buffering make it works.<br><br>Cheers,<div>Rémi-C</div></div><div><div><div class="gmail_extra">
<br><br><div class="gmail_quote">2013/12/19 Rémi Cura <span dir="ltr"><<a href="mailto:remi.cura@gmail.com" target="_blank">remi.cura@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hey, thanks for the answer, and nice catch !<div>I'll try to simply buffer points,</div><div>then try th eother method to count</div>
<div><br></div><div>About performance : </div><div>this is not about plpgsql or C.</div>
<div>I did quit the same processing when importing files of 3 millions points to split into small 1*1*1 m cubes.</div><div>There were a lot of cubes (around 2k for 3 millions points), a lot of points (3 millions) with a lot of attributes (around 20 flaot/double per point), and it was around 60 sec/ file (for the data processing. Data reading from disk was little longer).</div>
<div><br></div><div><br></div><div>For a 50x50 pixels and a few thousand points I would expect around 200ms.</div><div><br></div><div><br></div><div>I suspect it all boils down to current pixel access mechanism.</div><div>
<b>Can you please confirm if there is or isn't a method to set/get several pixels at a time?</b></div><div><br></div><div>Thanks anyway,</div><div>I wouldn't have found =)</div><div><br></div><div>Cheers,</div><div>
Rémi-C</div><div><div><div class="gmail_extra"><br><br><div class="gmail_quote">2013/12/19 Pierre Racine <span dir="ltr"><<a href="mailto:Pierre.Racine@sbf.ulaval.ca" target="_blank">Pierre.Racine@sbf.ulaval.ca</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">"MEAN_OF_VALUES_AT_PIXEL_CENTROID", which is the default ST_ExtractToRaster() method, search for geometries intersecting with the centroid of the pixel (a point). That's the method you use both calls to ExtractToRaster(). As it's almost impossible that a point intersects a point, this is certainly not the right method to get the value of points inside the pixel. A proper method would be "MEAN_VALUE_OF_POINTS" or "MEAN_VALUE_OF_GEOMETRIES" or "FIRST_GEOMETRY_VALUE" which are not implemented...<br>
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I suggest you try 'COUNT_OF_POINTS' for now which will set each pixel value to the number of point intersecting with it. If you get it to work and you're satisfied with the performance I could help adding a method for your specific need.<br>
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Can't do anything about the performance. All this is pure pl/pgsql and it's as fast as it can. 5 seconds to compute 2500 pixels value using SQL is not that bad though if you're not on the web... Otherwise you should have a specific C function doing exactly what you want. Expect time and $$$.<br>
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Pierre<br><br></div><div></div></blockquote></div><br></div></div></div></div>
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