Hi,
There seems to be 37800 aerial photos in my tileindex, 10000 x 10000 or 12000 x
12000 pixels each, and system works like a charm. I wouldn't call 69.2 GB as a
massive dataset.
First thing to do is to stop using ASCII GRID which must be one of the most
unsuitable formats for a web map service. Server must always open the whole
image into memory because format does not support direct access to region of
interest. Your mode=map requests puts Mapserver to read all your 466 ASCII GRID
files into memory.
Convert your DSM files into tiled GeoTIFFs, create overviews, and set a
reasonable maxscaledenom for the layer so that no more than 40 or so files are
opened from the tileindex layer. Make a layer group and use some other layer at
small scales. All this is FAQ and you should find lot of reading from the
internet. The "Geoserver on steroids" presentations are good start. The
challenge is the same for all server brands.
-Jukka Rahkonen-
Wright, Simon M wrote:
Dear All
I'm trying to use the MapServer Tile Indexes to create a map service, and
ultimately a WMS, of some DSM data but am getting an Internal Server Error.
The DSM data are organised as 466 5 × 5 km rasters with a resolution of 1 × 1 m
with a total size of 69.2 GB. The data format is Esri ASCII GRID.
To test the use of Tile Indexes in MapServer I used the gdaltindex to create an
index shapefile for just twenty of the 5 × 5 km rasters and created a basic map
file:
MAP
IMAGETYPE PNG
EXTENT 240000 100000 250000 150000
SIZE 400 2000
PROJECTION
"init=epsg:27700"
END
LAYER
NAME "tiled-rasters"
STATUS ON
TILEINDEX
"/datastore/b81071f2-85b3-4e31-8506-cabe899f989a/b81071f2-85b3-4e31-8506-cabe899f989a_copy/index_file"
TILEITEM "location"
TYPE RASTER
PROJECTION
"init=epsg:27700"
END
END
END
When I request an image of the map with the URL
http://localhost:8080/cgi-bin/mapserv?map=/vagrant/maps/tiled-rasters.map&layer=tiled-rasters&mode=map
I get an "Internal Server Error".
Therefore I created a second index shapefile using the gdaltindex tool that
only contained one of the 5 × 5 km rasters and updated the map file to point to
the second index shapefile. When I request an image of the map I can see an
image of the DSM data as expected.
Therefore, am I asking too much of the tile indexing approach in MapServer to
work against a massive dataset - 69.2 GB in 466 raster datasets - or have
MapServer users been able to get tile indexing too work in MapServer against
large data volumes and can provide some guidance.
Many thanks in advance of any help that MapServer users can offer.
Best wishes, Simon.
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