[mapserver-users] Very poor WMS tiling performance with small area, ultra-high resolution image

[Avi Blackmore]

On Feb 15, 2016, at 1:16 AM, Schepers, Benjamin wrote:

> Hi,
>  
> you still pointed to the right answer, strategies like overviews and tiling are IMHO not scale-dependent. They depend on the pixel-dimension of the image and you have - let’s say - a not so small one ;-)
>  
> So converting to GeoTIFF with internal „Tiling“ could be the right strategy  for you (http://www.gdal.org/frmt_gtiff.html;  use “BigTIFF” if files are expected to be larger than 4GB) à hint: gdal_translate with “BIGTIFF=YES” and “TILED=YES” … and of course Overviews (gdaladdo; also possible with BigTIFF-option).
>  
> Compression for original and overviews, could be lossless “LZW” or  lossy „JPEG-YCBCR” for example, this would also substantially squeeze down the size an d depends on your needs…
>  
> I have a lot of aerial images with up to 250.000*150.000px (GSD up to 6cm) in that manner and they are serving really, really fast via mapserver. Not every GIS-software is able to read those tiled and compressed BigTiffs directly (due to the lack of support for this file-format), but ArcGIS and QGIS do well (both use GDAL) and all others could still use the WMS served from mapserver!


	Thanks for the advice.  I was already using GeoTIFFs with internal tiling, and compression.

	The issue turned out to be a bad directive in the mapfile.  Our Mapscript application was misconfigured to set LOAD_WHOLE_IMAGE=yes in the processing directives for small-area imagery.  I don't recall why this was done, but I changed it, and now the images load fine in tiled mode.  

	Thanks for your help.

--
Avi Blackmore
Head Programmer/System Administrator
Satshot Inc.

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