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

[Schepers, Benjamin]

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) --> 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!

Regards
Ben

Luftbild und Geoinformationssysteme
schepers at rvr-online.de

[cid:image001.jpg at 01D167C6.4912F620]

Kronprinzenstraße 35
45128 Essen
Germany
www.metropoleruhr.de

Von: mapserver-users [mailto:mapserver-users-bounces at lists.osgeo.org] Im Auftrag von Avi Blackmore
Gesendet: Freitag, 12. Februar 2016 23:28
An: mapserver-users at lists.osgeo.org
Betreff: [mapserver-users] Very poor WMS tiling performance with small area, ultra-high resolution image

Hello,

            We've been using Mapserver as, among other things, a WMS server for some time with satellite and aerial imagery, without problems.  We've been able to serve imagery of resolutions down to .25 meters without any significant performance hit.

            Today, we got a sample image from a new source, which has a resolution of 0.06 meters.  The image is 317 megabytes in size, and has dimensions of 17538 x 19035 pixels.  The file size is smaller than many of the Landsat or other images that we have displayed in the past.  However, we're finding that rendering this image is extremely expensive.  In particular, with tiled access, a la Google Maps, the WMS requests bog down our server to the point where all of its memory is consumed.

            I know that overviews, tiling, and such, are good strategies for reducing the render time on a large area, reasonably high resolution image.  But what would be good strategies for improving rendering time on this smaller, ultra-high resolution image?
--
Avi Blackmore
Head Programmer/System Administrator
Satshot Inc.

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