[gdal-dev] Improvements in GDAL Grid 2.01 vs 1.11.2 report

[nicolas.cadieux at archeotec.ca]

Hi,
I have been using Gdal_Grid to interpolate LiDAR files.  I use the NN 
algorithm.  I order to reduce any border effect, I have been stitching 
all of my files together creating one big file.

This created problems.  The first being the GDAL_Grid had a 16mb buffer 
and needed to recalculate the quad tree for each work buffer. I was 
instructed to increase the buffer and to recompile Gdal_grid.

These are the result for creating a NN raster using a 3 x 3 search 
radius for 517 127 949 points.

Gdal 1.11.2 with 16mb buffer:  no results.  I pulled the plug after 3 
week of processing.  (I had about 2 1/2 months to go!).
Gdal 1.11.2 recompiled with a 1.5GB buffer: 4h46 min
Gdal 2.1.0 dev released 2015/99/99 (downloaded binaries. This version 
now has no need to recalculate the quad tree for each work buffer:  1h22min.

This is on a Intel i7 extreme edition with 6 core + hyper threading 
turned on.  64GB of ram, SSD drive.

Both files look the same (will report back if not) except for the fact 
that the Gdal 2.1.0 version has no data values in the file (and the  
1.11.2 version has -32768) so that is an added extra bonus.

Thanks for you work.
Nicolas Cadieux
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