Hi, > > I want to convert some HYCOM data into GTiff format and I'm a little > lost on how to get started, whether I can do what I need just using a > vrt or if I'm going to have to write code to process the data. > > To start with I have placed gdalinfo on one file here: > http://imaptools.com:8080/dl/hycom-gdalinfo.txt > > The data comes from http://hycom.org/dataserver/glb-analysis > and I will need to be using GLBa0.08 dataset. > > I have two use cases: > > 1) The simple one is to extract say Band 1 into a georeferenced GTiff > and apply color to using color ranges without loosing the NODATA. I > think I can do later using .vrt, correct?
gdaldem color-relief can output to a VRT, but given that this netCDF file is georeferenced through a geolocation array, you'll likely have first to run gdalwarp -geoloc to have something useful at the end. > > I'm not sure how to deal with the georeferencing, because the download > site says: "Native hycom .[ab] data converted to NetCDF on native > Mercator-curvilinear HYCOM horizontal grid" but that does not seem in > sync with the Metadata in the file. > > 2) The more complicated case is that there are two files: > a) eastward_sea_water_velocity (aka: u, u-velocity) > b) northward_sea_water_velocity (aka: v, v-velocity) > that I would like to use to create a grid of vectors with arrowheads > using u and v to define the vector and where the color of the vector is > related to the magnitude of its length. Ultimately this data will get > rendered via mapserver so I'm wondering if I can do this via a GTiff or > if I will have to resort to creating a massive point shapefile with > attributes of angle and magnitude and use a symbol. It seems like it > would be best if I can keep the data as a GTiff and then sample the > points and render the vectors on the fly for when you zoom in/out. See http://mapserver.org/input/vector/vector_field.html You don't need to create a vector file. You'll have to preprocess your file to get the u and v bands in the same raster. Even -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
