David Baker (Geoscience <david.m.baker <at> chk.com> writes: > > Jukka, > > Jukka wrote: > >I was experimenting with something like a "GIS service without a GIS server) > >and I have some examples online but... > > I am looking to do as you have, a RESTful service to query the elevation at a given location. This will be used > to in a DQM process as well as a geologic application that needs the elevation of a proposed wellsite for > data mining. In both cases, 1000's if not tens of 1000's of calls will be made so performance is an issue.
I don't believe that gdallocationinfo is the right thing for you. There are only 60 seconds in a minute and our experiments show that each request takes seconds or even tens of seconds. Your users will hang you. Now what to do instead? A WMS/WCS service can send a piece of DEM with thousands of pixels as GeoTIFF in a second and a heavy client like QGIS could continue the analysis. Or you can use the existing vrt file and read the region of interest with gdal_translate. This request is not very fast either but it brings you one million height values faster than possible users could find the rope gdal_translate -of GTiff -srcwin 10000 10000 1000 1000 /vsicurl/http://latuviitta.kapsi.fi/data/dem10m/dem_10m.vrt test_1000by1000.tif Or then WFS service could be used to send only thos DEM cells which intersect the requested point/line/area. That could be nice for further processing but in that case your DEM should be converted into points or polygons. I wonder if PostGIS raster has something to give for you. Or perhaps there is some other clever way to do the job with light and powerful tools. Ideas are welcome. -Jukka Rahkonen- _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev