For the record : when outputting the image to disk then loading it into postgis, image shows fine (band 1 and band2)
When 'add canvas' on the image in QGIS, a nex layer is created, but empty. Do you know other way to do it? Cheers, Rémi-C 2013/12/19 Rémi Cura <remi.c...@gmail.com> > QGis 2.0.1. > I tried as well to convert to UINT16 > no sucess > > > 2013/12/19 Rémi Cura <remi.c...@gmail.com> > >> Is there a special trick to display the raster in QGIS? >> I do >> db manage/right click on the raster table/add to canvas >> Seems like there is nothing in it afterward. >> >> Thanks again, >> >> Rémi-C >> >> >> 2013/12/19 Rémi Cura <remi.c...@gmail.com> >> >>> Buffering make it works. >>> >>> Cheers, >>> Rémi-C >>> >>> >>> 2013/12/19 Rémi Cura <remi.c...@gmail.com> >>> >>>> Hey, thanks for the answer, and nice catch ! >>>> I'll try to simply buffer points, >>>> then try th eother method to count >>>> >>>> About performance : >>>> this is not about plpgsql or C. >>>> I did quit the same processing when importing files of 3 millions >>>> points to split into small 1*1*1 m cubes. >>>> 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). >>>> >>>> >>>> For a 50x50 pixels and a few thousand points I would expect around >>>> 200ms. >>>> >>>> >>>> I suspect it all boils down to current pixel access mechanism. >>>> *Can you please confirm if there is or isn't a method to set/get >>>> several pixels at a time?* >>>> >>>> Thanks anyway, >>>> I wouldn't have found =) >>>> >>>> Cheers, >>>> Rémi-C >>>> >>>> >>>> 2013/12/19 Pierre Racine <pierre.rac...@sbf.ulaval.ca> >>>> >>>>> "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... >>>>> >>>>> 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. >>>>> >>>>> 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 $$$. >>>>> >>>>> Pierre >>>>> >>>>> >>>> >>> >> >
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