Re: [gdal-dev] how to aggregate an image to a lower resolution using gdal (gdalwarp?)

2013-12-06 Thread Etienne Tourigny
Jan, can you please add your sample dataset and comments in that ticket? Etienne On Tue, Dec 3, 2013 at 6:37 PM, Etienne B. Racine etienn...@gmail.comwrote: I added a ticket http://trac.osgeo.org/gdal/ticket/5311 Etienne 2013/12/2 Etienne Tourigny etourigny@gmail.com The average

Re: [gdal-dev] how to aggregate an image to a lower resolution using gdal (gdalwarp?)

2013-12-06 Thread Etienne B. Racine
Etienne, I've added the relevant files. I think it's sufficient to debug the function, but if you think it might be helpful, I could add a larger raster and the results of the aggregation. Etienne 2013/12/6 Etienne Tourigny etourigny@gmail.com Jan, can you please add your sample dataset

Re: [gdal-dev] how to aggregate an image to a lower resolution using gdal (gdalwarp?)

2013-12-06 Thread Etienne Tourigny
I have attached a patch to the ticket that fixes the problem. Anyone interested is welcome to test it. regards, Etienne On Fri, Dec 6, 2013 at 1:58 PM, Etienne B. Racine etienn...@gmail.comwrote: Etienne, I've added the relevant files. I think it's sufficient to debug the function, but if

Re: [gdal-dev] how to aggregate an image to a lower resolution using gdal (gdalwarp?)

2013-12-03 Thread Etienne B. Racine
I added a ticket http://trac.osgeo.org/gdal/ticket/5311 Etienne 2013/12/2 Etienne Tourigny etourigny@gmail.com The average resampling mode of gdalwarp does average resampling, computes the average of all non-NODATA contributing pixels. It was meant to compute the average of all the

Re: [gdal-dev] how to aggregate an image to a lower resolution using gdal (gdalwarp?)

2013-12-02 Thread Etienne B. Racine
I've tried to dig this a bit. I couldn't understand the logic behind gdal aggregation (or downsampling). I've simplified your example using a smaller raster and deterministic values. Maybe someone could enlighten us by looking at the aggregation values ? Note that the lower right cells values were

Re: [gdal-dev] how to aggregate an image to a lower resolution using gdal (gdalwarp?)

2013-12-02 Thread Etienne Tourigny
The average resampling mode of gdalwarp does average resampling, computes the average of all non-NODATA contributing pixels. It was meant to compute the average of all the pixels in the aggregation window. However, it may have issues in the corners. I am the author of the average and mode

[gdal-dev] how to aggregate an image to a lower resolution using gdal (gdalwarp?)

2013-08-27 Thread Verbesselt, Jan
Hi all, I have been testing gdalwarp to aggregate (using -r average) an image. In order to better understand what is happening I have created a reproducible example within an R environment and compared it with the aggregate function of the R raster package (see below). There are some differences