[gdal-dev] OGR XYZ -> GDAL VRT?
Hi all, does anyone know a way to put up a GDAL VRT fed by an OGR datasource that has data in XYZ format (regular gridded) . It doesn't have to ultimately be a VRT, just some similar on-the-fly raster format method, so I can share raster data directly from the OGR datasource. I've been digging around and saw wkt raster/postgis raster but it's really a little different than this approach as it doesn't use arrays. I can share more but thought I'd keep it simple first ;-) Any tips? Tyler Tyler Mitchell Engineering Director Actian Corporation tyler.mitch...@actian.com MOBILE 250-303-1831 SKYPE spatialguru www.actian.com ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
Re: [gdal-dev] OGR XYZ -> GDAL VRT?
Le jeudi 20 décembre 2012 02:08:01, vous avez écrit : > Hi all, does anyone know a way to put up a GDAL VRT fed by an OGR > datasource that has data in XYZ format (regular gridded) . > > It doesn't have to ultimately be a VRT, just some similar on-the-fly raster > format method, so I can share raster data directly from the OGR > datasource. I've been digging around and saw wkt raster/postgis raster > but it's really a little different than this approach as it doesn't use > arrays. > > I can share more but thought I'd keep it simple first ;-) Tyler, There's a GDAL XYZ driver, but it has very strict requirements : http://gdal.org/frmt_xyz.html Otherwise you can use the OGR CSV driver (make sure the file extension is .csv), wrap it in a OGR VRT, and then ingest that in gdal_grid to produce a raster. But that's not really on-the-fly. Even ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
Re: [gdal-dev] OGR XYZ -> GDAL VRT?
On 2012-12-19, at 10:54 PM, Even Rouault wrote: > Le jeudi 20 décembre 2012 02:08:01, vous avez écrit : >> Hi all, does anyone know a way to put up a GDAL VRT fed by an OGR >> datasource that has data in XYZ format (regular gridded) . >> >> It doesn't have to ultimately be a VRT, just some similar on-the-fly raster >> format method, so I can share raster data directly from the OGR >> datasource. I've been digging around and saw wkt raster/postgis raster >> but it's really a little different than this approach as it doesn't use >> arrays. >> >> I can share more but thought I'd keep it simple first ;-) > > Tyler, > > There's a GDAL XYZ driver, but it has very strict requirements : > http://gdal.org/frmt_xyz.html > > Otherwise you can use the OGR CSV driver (make sure the file extension is > .csv), wrap it in a OGR VRT, and then ingest that in gdal_grid to produce a > raster. But that's not really on-the-fly. Hi Even, Thanks for the tips I'm so close .. thanks to the XYZ driver which I've been using a lot lately, since I can input/output CSV and both GDAL and OGR can read it, but yeah, GDAL can't read it directly from the db source. My challenge is now to make it pull the CSV from the db in real-time via a VRT. (Actually I'm sure I can do it with a SQL statement in a VRT, my db is just not cooperating at the moment, since it's a non-spatial version of the Ingres db and the OGR driver is looking for geometry_columns table and bails out.) But, yeah it's still not on-the-fly from a GDAL raster perspective. I assume some of the other drivers (DODS?) do have a similar mechanism to deal with grids in databases? Isn't there some fancy bash scripting that can be done to masquerade an OGR VRT/script as a virtual file - e.g. it looks like a data file but it's really a realtime script inside it. Which leads me to wonder if there are ways to pipe CSV data into gdalinfo/translate? Hm... thanks again, I'll keep pick away on it when I have time. A generic gdal-ogr CSV bridge driver would be cool! Some for rambling, it's getting late ;) Tyler ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
Re: [gdal-dev] OGR XYZ -> GDAL VRT?
Tyler, A while back I had a need to access (by Mapserver) points stored in a non-spatial SQL Server database. I was able to use OGR's VRT to access the data, and while the example below shows a datasource connection of ODBC, you may be able to use an Oracle OCI connection instead: ODBC:auser/apass@dsname,Wells_view SELECT * FROM Wells_view WHERE SurfaceLongitude > -117.684 AND SurfaceLongitude < -117.682 AND SurfaceLatitude > 52.499 AND SurfaceLatitude < 52.5 wkbPoint NAD83 y='SurfaceLatitude' x='SurfaceLongitude'/> Actually, I'm a little confused by the GeometryType and GeometryField tags in the above example; you may need to experiment. I've also constructed views in the database, basically reformatting the lat/lon columns into WKT format to do: ODBC:auser/apass@dsname,vWM_UserGraphics SELECT WKT,PropertyID,GeomType,GeomID,LayerName,ClassName,Label FROM vWM_UserGraphics WHERE PropertyID=%PropertyID% ANDGeomType = 0 geomID wkbLineString NAD83 Note the "%PropertyID%" string is a Mapserver runtime substitution done before OGR gets the VRT definition so not very useful in your case (but it might give you a few ideas). Hopefully I've understood at least some of what you are trying to accomplish. At first I thought you wanted a GDAL VRT that defines a raster, referencing an OGR VRT as the source data and defining a method of producing a grid. Yikes! Best Regards, Brent Fraser On 12/20/2012 12:50 AM, Tyler Mitchell wrote: On 2012-12-19, at 10:54 PM, Even Rouault wrote: Le jeudi 20 décembre 2012 02:08:01, vous avez écrit : Hi all, does anyone know a way to put up a GDAL VRT fed by an OGR datasource that has data in XYZ format (regular gridded) . It doesn't have to ultimately be a VRT, just some similar on-the-fly raster format method, so I can share raster data directly from the OGR datasource. I've been digging around and saw wkt raster/postgis raster but it's really a little different than this approach as it doesn't use arrays. I can share more but thought I'd keep it simple first ;-) Tyler, There's a GDAL XYZ driver, but it has very strict requirements : http://gdal.org/frmt_xyz.html Otherwise you can use the OGR CSV driver (make sure the file extension is .csv), wrap it in a OGR VRT, and then ingest that in gdal_grid to produce a raster. But that's not really on-the-fly. Hi Even, Thanks for the tips I'm so close .. thanks to the XYZ driver which I've been using a lot lately, since I can input/output CSV and both GDAL and OGR can read it, but yeah, GDAL can't read it directly from the db source. My challenge is now to make it pull the CSV from the db in real-time via a VRT. (Actually I'm sure I can do it with a SQL statement in a VRT, my db is just not cooperating at the moment, since it's a non-spatial version of the Ingres db and the OGR driver is looking for geometry_columns table and bails out.) But, yeah it's still not on-the-fly from a GDAL raster perspective. I assume some of the other drivers (DODS?) do have a similar mechanism to deal with grids in databases? Isn't there some fancy bash scripting that can be done to masquerade an OGR VRT/script as a virtual file - e.g. it looks like a data file but it's really a realtime script inside it. Which leads me to wonder if there are ways to pipe CSV data into gdalinfo/translate? Hm... thanks again, I'll keep pick away on it when I have time. A generic gdal-ogr CSV bridge driver would be cool! Some for rambling, it's getting late ;) Tyler ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
Re: [gdal-dev] OGR XYZ -> GDAL VRT?
On 2012-12-20, at 7:34 AM, Brent Fraser wrote: > I've also constructed views in the database, basically reformatting the > lat/lon columns into WKT format to do: Hi Brent, you gave some good examples, thanks. This has been the approach I took so far, but is not precisely what I'm after. > Hopefully I've understood at least some of what you are trying to accomplish. > At first I thought you wanted a GDAL VRT that defines a raster, referencing > an OGR VRT as the source data and defining a method of producing a grid. > Yikes! Yeah, that's the ticket actually :) Think of it as poor-man's raster-in-db solution - a table with X, Y, Z columns - I'm looking for the best way to let GDAL pull that data out and re-assemble it as a raster. I can do it programatically but want to do it on the fly, so MapServer, QGIS, etc. can simply use it. Thanks again, Tyler ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
Re: [gdal-dev] OGR XYZ -> GDAL VRT?
Hmmm. You need the GDAL-VRT format to have the same data-source flexibility currently in the OGR-VRT. Could be a useful enhancement with the growing interest in storing rasters in a RDBMs... Best Regards, Brent Fraser On 12/20/2012 10:38 AM, Tyler Mitchell wrote: On 2012-12-20, at 7:34 AM, Brent Fraser wrote: I've also constructed views in the database, basically reformatting the lat/lon columns into WKT format to do: Hi Brent, you gave some good examples, thanks. This has been the approach I took so far, but is not precisely what I'm after. Hopefully I've understood at least some of what you are trying to accomplish. At first I thought you wanted a GDAL VRT that defines a raster, referencing an OGR VRT as the source data and defining a method of producing a grid. Yikes! Yeah, that's the ticket actually :) Think of it as poor-man's raster-in-db solution - a table with X, Y, Z columns - I'm looking for the best way to let GDAL pull that data out and re-assemble it as a raster. I can do it programatically but want to do it on the fly, so MapServer, QGIS, etc. can simply use it. Thanks again, Tyler ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
