RE: [gdal-dev] How to represent multi-dimensional array
The trick is your netCDF has to meet a bunch of constraints for ArcGIS to recognize it. It has to have square cells. bingo -- that was one of our key problems -- wait -- they have to be square -- rectangular won't do? arrgg! Oops, I'm pretty sure you're right, they can be rectangular so long as the increment is constant. I recall working with some climate model output that was rectangular with a constant increment (2 deg latitude, 3 deg longitude). I checked the documentation and it confirms this. The limitation is that it cannot work with rectangular cells that have an irregular increment (what MATLAB calls plaid, I think), or work with non-rectangular cells. Jason -Original Message- From: gdal-dev-boun...@lists.osgeo.org [mailto:gdal-dev-boun...@lists.osgeo.org] On Behalf Of Christopher Barker Sent: Saturday, June 19, 2010 5:45 PM To: gdal-dev@lists.osgeo.org Subject: Re: [gdal-dev] How to represent multi-dimensional array Thanks to Michael, Joaquim, Ivan, and Jason. I'll explore some of the tools and suggestions you made. Michael Sumner wrote: NetCDF will tend to store dimensions in reverse order to the natural one, and I think GDAL reverses that - but you can tell by the dimension and number of your bands, and the named metadata on the GDAL bands. yup -- I figured that out - it got better when we re-ordered to (t, z, y, x). NetCDF cannot store multi-attribute arrays (it will store several same-size, same-metadata arrays for that purpose), Actually, I think it can -- though maybe that's only for netcdf4 (based on hdf5), but the conventions don't suggest you do that -- particularly if different attributes are different data types. Manifold reads in multiple rasters Eonfusion will do its best to read the array in its natural state R can read NetCDF natively or with GDAL (RNetCDF, ncdf, rgdal We're not really looking for other tools at this point -- we are doing visualization with IDV, which handles 4-d data in netcdf just fine. This part is all about getting this data into Arc. I may deal with it by figuring out what we really need to do in Arc, and just exporting that part of the data -- we're writing these files with Python anyway, so doing some pre-processing there won't be a big deal. Joaquim Luis wrote: Don't know if this is what you are looking for but if those netCDF files are of a similar type that one can get from the poet site (http://poet.jpl.nasa.gov/), Mirone has a tool called Aquamoto (a tool original developed to show time stamps of a tsunami propagation models) that loads those files and show their content interactively with the help of a slider. Not much help for this, but it's a cool tool, thanks for the link. Jason Roberts wrote: I have some experience trying to get ArcGIS to work well with time series satellite imagery and 4D ocean models (e.g. HYCOM, ROMS). Exactly our situation, here. I am part of a working group initiated by ESRI and led by an ESRI program manager (Nawajish Noman) that is trying, in essence, to get the community of users who use both ArcGIS and netCDF to develop some Python geoprocessing tools for ArcGIS that provide more functionality than out-of-box tools already in ArcGIS. cool -- do you have contact information for that project? Is there code anywhere we can get at it? 1. The Make NetCDF Raster Layer tool can represent 3D netCDF variables as multiband raster layers. We'll give this a try. It may be what our GIS person is using already, but I got a bit confused by the Dimension Values parameter. We'll poke at it some more. The trick is your netCDF has to meet a bunch of constraints for ArcGIS to recognize it. It has to have square cells. bingo -- that was one of our key problems -- wait -- they have to be square -- rectangular won't do? arrgg! Anyway, the way we have it now the cells ar rectangular in meters, but we un-projectee them to lat-long, so they are no longer simle rectangular -- I think I may change this an output in meters, with the projection info. But if it has to be square, we're kind of dea in the water... It has adhere to the CF or COARDS conventions (I forget which versions) that we do have. 2. Under contract to NOAA, Applied Science Associates built a couple of tools that might be useful: the Environmental Data Connector (EDC) and TimeSlider Extension. Download from http://www.asascience.com/software/downloads/index.shtml, see other parts of the website for more info. EDC was built to download multidimensional OPeNDAP datasets into multiband rasters. Hmm -- did know about those tools, but didn't realize that EDC was OPenDAP based -- nice to know. TimeSlider is a UI extension to help with playback of time-series data. That too -- by the way, I'm pretty sure the Coast Guard funded a bunhc of that, for their Search and Rescue tools. I think they can both work with netCDFs directly, not just OPeNDAP. That I didn't know -- we'll try
Re: [gdal-dev] How to represent multi-dimensional array
Jason Roberts wrote: The trick is your netCDF has to meet a bunch of constraints for ArcGIS to recognize it. It has to have square cells. bingo -- that was one of our key problems -- wait -- they have to be square -- rectangular won't do? arrgg! Oops, I'm pretty sure you're right, they can be rectangular so long as the increment is constant. I recall working with some climate model output that was rectangular with a constant increment (2 deg latitude, 3 deg longitude). I checked the documentation and it confirms this. That's better, and makes sense -- other raster data works that way. The limitation is that it cannot work with rectangular cells that have an irregular increment which indeed is what we were trying to do. Actually, the cells were rectangular in projected coordinates (where we did the computation), but weren't in lat-long, which is what we were exporting. So I should be able to fix that. -thanks, -Chris Jason -Original Message- From: gdal-dev-boun...@lists.osgeo.org [mailto:gdal-dev-boun...@lists.osgeo.org] On Behalf Of Christopher Barker Sent: Saturday, June 19, 2010 5:45 PM To: gdal-dev@lists.osgeo.org Subject: Re: [gdal-dev] How to represent multi-dimensional array Thanks to Michael, Joaquim, Ivan, and Jason. I'll explore some of the tools and suggestions you made. Michael Sumner wrote: NetCDF will tend to store dimensions in reverse order to the natural one, and I think GDAL reverses that - but you can tell by the dimension and number of your bands, and the named metadata on the GDAL bands. yup -- I figured that out - it got better when we re-ordered to (t, z, y, x). NetCDF cannot store multi-attribute arrays (it will store several same-size, same-metadata arrays for that purpose), Actually, I think it can -- though maybe that's only for netcdf4 (based on hdf5), but the conventions don't suggest you do that -- particularly if different attributes are different data types. Manifold reads in multiple rasters Eonfusion will do its best to read the array in its natural state R can read NetCDF natively or with GDAL (RNetCDF, ncdf, rgdal We're not really looking for other tools at this point -- we are doing visualization with IDV, which handles 4-d data in netcdf just fine. This part is all about getting this data into Arc. I may deal with it by figuring out what we really need to do in Arc, and just exporting that part of the data -- we're writing these files with Python anyway, so doing some pre-processing there won't be a big deal. Joaquim Luis wrote: Don't know if this is what you are looking for but if those netCDF files are of a similar type that one can get from the poet site (http://poet.jpl.nasa.gov/), Mirone has a tool called Aquamoto (a tool original developed to show time stamps of a tsunami propagation models) that loads those files and show their content interactively with the help of a slider. Not much help for this, but it's a cool tool, thanks for the link. Jason Roberts wrote: I have some experience trying to get ArcGIS to work well with time series satellite imagery and 4D ocean models (e.g. HYCOM, ROMS). Exactly our situation, here. I am part of a working group initiated by ESRI and led by an ESRI program manager (Nawajish Noman) that is trying, in essence, to get the community of users who use both ArcGIS and netCDF to develop some Python geoprocessing tools for ArcGIS that provide more functionality than out-of-box tools already in ArcGIS. cool -- do you have contact information for that project? Is there code anywhere we can get at it? 1. The Make NetCDF Raster Layer tool can represent 3D netCDF variables as multiband raster layers. We'll give this a try. It may be what our GIS person is using already, but I got a bit confused by the Dimension Values parameter. We'll poke at it some more. The trick is your netCDF has to meet a bunch of constraints for ArcGIS to recognize it. It has to have square cells. bingo -- that was one of our key problems -- wait -- they have to be square -- rectangular won't do? arrgg! Anyway, the way we have it now the cells ar rectangular in meters, but we un-projectee them to lat-long, so they are no longer simle rectangular -- I think I may change this an output in meters, with the projection info. But if it has to be square, we're kind of dea in the water... It has adhere to the CF or COARDS conventions (I forget which versions) that we do have. 2. Under contract to NOAA, Applied Science Associates built a couple of tools that might be useful: the Environmental Data Connector (EDC) and TimeSlider Extension. Download from http://www.asascience.com/software/downloads/index.shtml, see other parts of the website for more info. EDC was built to download multidimensional OPeNDAP datasets into multiband rasters. Hmm -- did know about those tools, but didn't realize that EDC was OPenDAP based -- nice to know. TimeSlider is a UI extension
Re: [gdal-dev] How to represent multi-dimensional array
I find this categorization helpful: http://en.wikipedia.org/wiki/Regular_grid Any GIS will do regular and cartesian grids (but usually bound to 2D), and with programming constructs you can handle rectlinear or curvilinear grids of any dimension, but it's not well supported in high-level software AFAIK. Unfortunately GIS is traditionally bound to the regular case for 2D only - probably because globe-surface projections were an over-arching for the early layers. AFAIK, modern ArcGIS can use GDAL to read rasters, so it would be profound if it were limited to square cells - the ESRI ascii grid format is limited to square cells, though some software allows separate XDIM/YDIM values. http://www.gdal.org/frmt_various.html#AAIGrid Jason: are there plans for full multi-dimensional / curvilinear / multiband grid support in MGET? What do you think of the rasdaman project - any ties with MGET? Eonfusion can represent and visualize these, but there is only a narrow path for generating them via GDAL (auxiliary time files or NetCDF arrays), making full multi-band support a bit awkward - and then formats like GRIB add another level of complication, interleaving bands and dimensions etc. Cheers, Mike. On Tue, Jun 22, 2010 at 1:17 AM, Jason Roberts jason.robe...@duke.edu wrote: The trick is your netCDF has to meet a bunch of constraints for ArcGIS to recognize it. It has to have square cells. bingo -- that was one of our key problems -- wait -- they have to be square -- rectangular won't do? arrgg! Oops, I'm pretty sure you're right, they can be rectangular so long as the increment is constant. I recall working with some climate model output that was rectangular with a constant increment (2 deg latitude, 3 deg longitude). I checked the documentation and it confirms this. The limitation is that it cannot work with rectangular cells that have an irregular increment (what MATLAB calls plaid, I think), or work with non-rectangular cells. Jason -Original Message- From: gdal-dev-boun...@lists.osgeo.org [mailto:gdal-dev-boun...@lists.osgeo.org] On Behalf Of Christopher Barker Sent: Saturday, June 19, 2010 5:45 PM To: gdal-dev@lists.osgeo.org Subject: Re: [gdal-dev] How to represent multi-dimensional array Thanks to Michael, Joaquim, Ivan, and Jason. I'll explore some of the tools and suggestions you made. Michael Sumner wrote: NetCDF will tend to store dimensions in reverse order to the natural one, and I think GDAL reverses that - but you can tell by the dimension and number of your bands, and the named metadata on the GDAL bands. yup -- I figured that out - it got better when we re-ordered to (t, z, y, x). NetCDF cannot store multi-attribute arrays (it will store several same-size, same-metadata arrays for that purpose), Actually, I think it can -- though maybe that's only for netcdf4 (based on hdf5), but the conventions don't suggest you do that -- particularly if different attributes are different data types. Manifold reads in multiple rasters Eonfusion will do its best to read the array in its natural state R can read NetCDF natively or with GDAL (RNetCDF, ncdf, rgdal We're not really looking for other tools at this point -- we are doing visualization with IDV, which handles 4-d data in netcdf just fine. This part is all about getting this data into Arc. I may deal with it by figuring out what we really need to do in Arc, and just exporting that part of the data -- we're writing these files with Python anyway, so doing some pre-processing there won't be a big deal. Joaquim Luis wrote: Don't know if this is what you are looking for but if those netCDF files are of a similar type that one can get from the poet site (http://poet.jpl.nasa.gov/), Mirone has a tool called Aquamoto (a tool original developed to show time stamps of a tsunami propagation models) that loads those files and show their content interactively with the help of a slider. Not much help for this, but it's a cool tool, thanks for the link. Jason Roberts wrote: I have some experience trying to get ArcGIS to work well with time series satellite imagery and 4D ocean models (e.g. HYCOM, ROMS). Exactly our situation, here. I am part of a working group initiated by ESRI and led by an ESRI program manager (Nawajish Noman) that is trying, in essence, to get the community of users who use both ArcGIS and netCDF to develop some Python geoprocessing tools for ArcGIS that provide more functionality than out-of-box tools already in ArcGIS. cool -- do you have contact information for that project? Is there code anywhere we can get at it? 1. The Make NetCDF Raster Layer tool can represent 3D netCDF variables as multiband raster layers. We'll give this a try. It may be what our GIS person is using already, but I got a bit confused by the Dimension Values parameter. We'll poke at it some more. The trick is your netCDF has to meet a bunch of constraints
Re: [gdal-dev] How to represent multi-dimensional array
Thanks to Michael, Joaquim, Ivan, and Jason. I'll explore some of the tools and suggestions you made. Michael Sumner wrote: NetCDF will tend to store dimensions in reverse order to the natural one, and I think GDAL reverses that - but you can tell by the dimension and number of your bands, and the named metadata on the GDAL bands. yup -- I figured that out - it got better when we re-ordered to (t, z, y, x). NetCDF cannot store multi-attribute arrays (it will store several same-size, same-metadata arrays for that purpose), Actually, I think it can -- though maybe that's only for netcdf4 (based on hdf5), but the conventions don't suggest you do that -- particularly if different attributes are different data types. Manifold reads in multiple rasters Eonfusion will do its best to read the array in its natural state R can read NetCDF natively or with GDAL (RNetCDF, ncdf, rgdal We're not really looking for other tools at this point -- we are doing visualization with IDV, which handles 4-d data in netcdf just fine. This part is all about getting this data into Arc. I may deal with it by figuring out what we really need to do in Arc, and just exporting that part of the data -- we're writing these files with Python anyway, so doing some pre-processing there won't be a big deal. Joaquim Luis wrote: Don't know if this is what you are looking for but if those netCDF files are of a similar type that one can get from the poet site (http://poet.jpl.nasa.gov/), Mirone has a tool called Aquamoto (a tool original developed to show time stamps of a tsunami propagation models) that loads those files and show their content interactively with the help of a slider. Not much help for this, but it's a cool tool, thanks for the link. Jason Roberts wrote: I have some experience trying to get ArcGIS to work well with time series satellite imagery and 4D ocean models (e.g. HYCOM, ROMS). Exactly our situation, here. I am part of a working group initiated by ESRI and led by an ESRI program manager (Nawajish Noman) that is trying, in essence, to get the community of users who use both ArcGIS and netCDF to develop some Python geoprocessing tools for ArcGIS that provide more functionality than out-of-box tools already in ArcGIS. cool -- do you have contact information for that project? Is there code anywhere we can get at it? 1. The Make NetCDF Raster Layer tool can represent 3D netCDF variables as multiband raster layers. We'll give this a try. It may be what our GIS person is using already, but I got a bit confused by the Dimension Values parameter. We'll poke at it some more. The trick is your netCDF has to meet a bunch of constraints for ArcGIS to recognize it. It has to have square cells. bingo -- that was one of our key problems -- wait -- they have to be square -- rectangular won't do? arrgg! Anyway, the way we have it now the cells ar rectangular in meters, but we un-projectee them to lat-long, so they are no longer simle rectangular -- I think I may change this an output in meters, with the projection info. But if it has to be square, we're kind of dea in the water... It has adhere to the CF or COARDS conventions (I forget which versions) that we do have. 2. Under contract to NOAA, Applied Science Associates built a couple of tools that might be useful: the Environmental Data Connector (EDC) and TimeSlider Extension. Download from http://www.asascience.com/software/downloads/index.shtml, see other parts of the website for more info. EDC was built to download multidimensional OPeNDAP datasets into multiband rasters. Hmm -- did know about those tools, but didn't realize that EDC was OPenDAP based -- nice to know. TimeSlider is a UI extension to help with playback of time-series data. That too -- by the way, I'm pretty sure the Coast Guard funded a bunhc of that, for their Search and Rescue tools. I think they can both work with netCDFs directly, not just OPeNDAP. That I didn't know -- we'll try that out. 3. If you don't want to use netCDFs, you can fake multidimensionality for some scenarios by building a raster catalog with columns for the time and depth. I have no idea how to do that -- can GDAL build a raster catalog? 4. My group, the Duke University Marine Geospatial Ecology Lab, is currently building 3D and 4D awareness into a collection of tools we publish, Marine Geospatial Ecology Tools (MGET, see http://code.nicholas.duke.edu/projects/mget), built in Python on GDAL and other FOSS packages. Very cool. I'll keep an eye on that. Thanks for everyone's help, -Chris -- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/ORR(206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception chris.bar...@noaa.gov ___ gdal-dev mailing list gdal-dev@lists.osgeo.org
RE: [gdal-dev] How to represent multi-dimensional array
Chris, I have some experience trying to get ArcGIS to work well with time series satellite imagery and 4D ocean models (e.g. HYCOM, ROMS). Similar to GDAL, it does not appear that multidimensionality was designed into the current versions of ArcGIS. Like GDAL, ArcGIS appears mainly designed to work with 2D images. Both support multi-band 2D images very well, and this can be used to at least access 3D data although there is not good support for understanding the value of the z coordinate. As far as I am aware, ESRI is not currently making significant investments in the area of multidimensional data. I am part of a working group initiated by ESRI and led by an ESRI program manager (Nawajish Noman) that is trying, in essence, to get the community of users who use both ArcGIS and netCDF to develop some Python geoprocessing tools for ArcGIS that provide more functionality than out-of-box tools already in ArcGIS. ESRI did not provide any of their own developers. I donated some dev time and prototyped a tool for them using the netcdf4-python package and others are carrying on from there. I do not believe this project will result in anything dramatically new but it might yield a few additional useful geoprocessing tools. I have reduced my participation after concluding that it makes more sense to focus on the development of my own project (see below). Here are some options I'm aware of with ArcGIS: 1. The Make NetCDF Raster Layer tool can represent 3D netCDF variables as multiband raster layers. Using the Dimension Values parameter, you can slice a 3D slab out of a 4D or higher-dimensional variable. This tool might be sufficient for your purposes. The trick is your netCDF has to meet a bunch of constraints for ArcGIS to recognize it. It has to have square cells. It has adhere to the CF or COARDS conventions (I forget which versions) and have all the right attributes. You can learn more about this in the ArcGIS Desktop Help under netCDF data, FAQs about. Also see netCDF data, animating and the other topics under netCDF data. 2. Under contract to NOAA, Applied Science Associates built a couple of tools that might be useful: the Environmental Data Connector (EDC) and TimeSlider Extension. Download from http://www.asascience.com/software/downloads/index.shtml, see other parts of the website for more info. EDC was built to download multidimensional OPeNDAP datasets into multiband rasters. TimeSlider is a UI extension to help with playback of time-series data. I think they can both work with netCDFs directly, not just OPeNDAP. Also look at ASA ViewNcDap, which can display multidimensional netCDF variables. (Although this last program is not an ArcGIS extension, and there are many other programs in the world that are also not ArcGIS extensions and that probably do as good or better a job.) 3. If you don't want to use netCDFs, you can fake multidimensionality for some scenarios by building a raster catalog with columns for the time and depth. For example, you can build an animation that selects slices by date as the animation plays through a range of dates. 4. My group, the Duke University Marine Geospatial Ecology Lab, is currently building 3D and 4D awareness into a collection of tools we publish, Marine Geospatial Ecology Tools (MGET, see http://code.nicholas.duke.edu/projects/mget), built in Python on GDAL and other FOSS packages. You can download MGET today, but the 3D and 4D awareness will not be there for several months so it probably won't be useful to you in the present form. When complete, these tools will allow you to run some common marine ecology scenarios directly from ArcGIS, such as building climatologies, sampling 3D and 4D datasets at points in time and space, identifying fronts, etc. Good luck, Jason -Original Message- From: gdal-dev-boun...@lists.osgeo.org [mailto:gdal-dev-boun...@lists.osgeo.org] On Behalf Of Christopher Barker Sent: Thursday, June 17, 2010 3:16 PM To: gdal-dev@lists.osgeo.org Subject: [gdal-dev] How to represent multi-dimensional array Hi folks, I have a dataset that is a 4-dimensional array of values: time,x,y,z We're currently using netcdf to store it, which is well suited to this kind of data. However, we also need to get it into a GIS (Arc in this case), and I'm trying to find a good way to do that. Both Arc and gdalinfo do strange things if I simply point them at the netcdf file. GDAL seems to (arbitrarily?) see it as a 9064 band data set, so it is taking particular slice (I think I'm getting a bunch of (time, z) 2-d bands. Anyway, I suspect that if I re-arrange the axis in the netcdf file, I might get something more reasonable, but my question is: What is a good format to ex[press this to a GIS system? I'm imaging multiple files, maybe geo-tiff, but how to I express time and elevation in a way that is natural to GIS? thanks for your thoughts, -Chris -- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/ORR
Re: [gdal-dev] How to represent multi-dimensional array
I don't think there is a GIS that does this in a natural way - all you can do is read in multiple slices. If the order of your axes really is time, x, y, z then you will have y.n * z.n (time, x) slices (as bands) when read by GDAL - NetCDF will tend to store dimensions in reverse order to the natural one, and I think GDAL reverses that - but you can tell by the dimension and number of your bands, and the named metadata on the GDAL bands. Later versions of ArcGIS allow time-sliced arrays I think, so you could store several of these. NetCDF cannot store multi-attribute arrays (it will store several same-size, same-metadata arrays for that purpose), so one thing you could do is allow the GIS to to store several multi-band arrays (an array for each T, a band for each Z) - but you need to wear the inconsistency of mixing attributes with dimensions. Manifold reads in multiple rasters and I presume ArcGIS does too. Eonfusion will do its best to read the array in its natural state, but it is interpreted through GDAL and the dimensions reconstructed from the band metadata, but it's not a traditional GIS in any sense. R can read NetCDF natively or with GDAL (RNetCDF, ncdf, rgdal packages) and convert to the Spatial classes, but these are limited to multi-band 2D arrays. Cheers, Mike. On Fri, Jun 18, 2010 at 5:15 AM, Christopher Barker chris.bar...@noaa.gov wrote: Hi folks, I have a dataset that is a 4-dimensional array of values: time,x,y,z We're currently using netcdf to store it, which is well suited to this kind of data. However, we also need to get it into a GIS (Arc in this case), and I'm trying to find a good way to do that. Both Arc and gdalinfo do strange things if I simply point them at the netcdf file. GDAL seems to (arbitrarily?) see it as a 9064 band data set, so it is taking particular slice (I think I'm getting a bunch of (time, z) 2-d bands. Anyway, I suspect that if I re-arrange the axis in the netcdf file, I might get something more reasonable, but my question is: What is a good format to ex[press this to a GIS system? I'm imaging multiple files, maybe geo-tiff, but how to I express time and elevation in a way that is natural to GIS? thanks for your thoughts, -Chris -- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/ORR (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception chris.bar...@noaa.gov ___ 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] How to represent multi-dimensional array
Don't know if this is what you are looking for but if those netCDF files are of a similar type that one can get from the poet site (http://poet.jpl.nasa.gov/), Mirone has a tool called Aquamoto (a tool original developed to show time stamps of a tsunami propagation models) that loads those files and show their content interactively with the help of a slider. Joaquim Hi folks, I have a dataset that is a 4-dimensional array of values: time,x,y,z We're currently using netcdf to store it, which is well suited to this kind of data. However, we also need to get it into a GIS (Arc in this case), and I'm trying to find a good way to do that. Both Arc and gdalinfo do strange things if I simply point them at the netcdf file. GDAL seems to (arbitrarily?) see it as a 9064 band data set, so it is taking particular slice (I think I'm getting a bunch of (time, z) 2-d bands. Anyway, I suspect that if I re-arrange the axis in the netcdf file, I might get something more reasonable, but my question is: What is a good format to ex[press this to a GIS system? I'm imaging multiple files, maybe geo-tiff, but how to I express time and elevation in a way that is natural to GIS? thanks for your thoughts, -Chris ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
Re: [gdal-dev] How to represent multi-dimensional array
Chris, Christopher Barker wrote: Hi folks, I have a dataset that is a 4-dimensional array of values: time,x,y,z We're currently using netcdf to store it, which is well suited to this kind of data. However, we also need to get it into a GIS (Arc in this case), and I'm trying to find a good way to do that. Both Arc and gdalinfo do strange things if I simply point them at the netcdf file. GDAL seems to (arbitrarily?) see it as a 9064 band data set, so it is taking particular slice (I think I'm getting a bunch of (time, z) 2-d bands. You might take a look a Idrisi (www.clarklabs.org). It imports netCDF using a GUI where you can choose the orders of the dimensions to read from. There is a set of tools to perform time series analysis. Anyway, I suspect that if I re-arrange the axis in the netcdf file, I might get something more reasonable, but my question is: What is a good format to ex[press this to a GIS system? I'm imaging multiple files, maybe geo-tiff, but how to I express time and elevation in a way that is natural to GIS? You might be forced to use multiple files just because that is how generally image processing tools work better. Then you could write scripts to loop trough the bands files with those tools. Although some operations on the time dimension could work much faster in a multi-band, pixel interleaving storage mode. Like you said, netCDF are well suited for that kind of processing. I am afraid that the tools are not, yet. thanks for your thoughts, -Chris Regards, Ivan ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
