[gdal-dev] guidance on NSIDC Sea Ice concentration data

Markus Müller markus.u.mueller at zoho.com
Sun Jul 26 19:47:56 PDT 2015

I submitted a ticket regarding this issue:https://trac.osgeo.org/gdal/ticket/6051

Thanks Andre for your help on gis.stackexchange and here.


Markus Mueller

---- On Sun, 26 Jul 2015 09:34:58 -0700 Andre Joost <andre+joost at nurfuerspam.de> wrote ---- 

Can this VRT approach be used for MODIS sea ice data too? 
note that especially older versions (before 2011) only produce garbage 
images with GDAL. 
André Joost 
Am 25.07.2015 um 00:56 schrieb Michael Sumner: 
> Hello, I've put together an example of using NSDIC sea ice concentration 
> data with GDAL VRT. 
> In this Github readme I list two example data sets, one for the Northern 
> and one for the Southern hemisphere where the raw 
> binary NSDIC .bin files have accompanying VRT files: 
> https://github.com/mdsumner/NSIDC-seaice 
> I'd really like to see this format as a GDAL driver, but I don't have the 
> C++ expertise to make it happen. I can offer help and testing if anyone was 
> interested in writing the driver, but I would also appreciate any guidance 
> and kick start for me to learn to do it myself. 
> The format itself is detailed here, and everything required can be gleaned 
> from the header - though in the VRT pathway I simply skip the header and 
> apply the right CRS, orientation, grid size and geotransform: 
> http://nsidc.org/data/docs/daac/nsidc0051_gsfc_seaice.gd.html#format 
> The repo includes the minimal .vrt required to read this as a valid GDAL 
> data set and uses plotting in R with standard R 
> mapping tools to show that the interpretation is right, at least visibly. 
> I have these questions: 
> * what is the best template driver for these data, should it derive from 
> GDALPamDataset like JDEM or from RawDataset as ERS does? (I'm way out of 
> my depth here) 
> * is it appropriate to use this SRS when the datum is unspecified? I'm not 
> clear on the pitfalls here and how to advise downstream use 
> I am competent with building GDAL but I get lost in the steps required to 
> add a new driver. A dummy example, or some more detailed guidance for how I 
> would apply the "GDAL Driver Implementation Tutorial" to these data would 
> be enough for me to flesh out the details. 
> The projection SRS used are EPSG 3411 (north) and 3412 (south) as listed 
> here: 
> http://spatialreference.org/ref/epsg/3411/ 
> http://spatialreference.org/ref/epsg/3412/ 
> I have otherwise written this support directly into the R package raster, 
> the R source for these files is here in this read-only mirror (raster is on 
> r-forge): 
> https://github.com/cran/raster/blob/master/R/nsidcICE.R 
> This works very well for R, but I'd prefer to see this format in GDAL so 
> that other languages have the same facility. There are other sea ice 
> concentration data sources, usually in HDF4 format - and they only need the 
> geotransform and SRS assigned for use in GDAL - so they need work as well 
> but not as fundamental as this raw binary format. This data source is very 
> extensive, with daily data at 25km resolution every day since 1979 with 
> only ~30 days total missing, and only a handful with problems in the map 
> coverage. 
> Thank you. 
> Cheers, Mike. 
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