[R-sig-Geo] Reproject MODIS data using R (results in NAs or no spatial extent)

[Michael Sumner]

Ah, never mind - it's the subdataset discovery that's probably not easy
with rgdal.
Sorry for the noise.

Mike.

On Fri, 30 Nov 2018 at 06:38 Michael Sumner <mdsumner using gmail.com> wrote:

> Fwiw there shouldn't be any need to convert from hdf to tif - could you
> please try this?
>
> x <- readGDAL( ".../GLASS02B05.V04.A1990161.2018062.hdf")
>
> If that works it at least removes some steps from your process.
>
> Cheers, Mike.
>
> On Fri, Nov 30, 2018, 05:03 Elizabeth Webb <webbe using ufl.edu> wrote:
>
>> I am using GLASS albedo data stored here<
>> ftp://ftp.glcf.umd.edu/glcf/GLASS/ABD/AVHRR/> for pre-2000 (AVHRR) data
>> and here<ftp://ftp.glcf.umd.edu/glcf/GLASS/ABD/MODIS/0.05D/> for
>> post-2000 data (MODIS). My end goal is to create a raster stack of each
>> month that contains white sky albedo data from 1982-2015. The problem I
>> have run into is that the MODIS and AVHRR data are in different spatial
>> reference systems and I can't seem to reproject them to be in the same
>> system.
>>
>> I convert from hdf to tif using R like this:
>>
>> fileavhrr <- ".../GLASS02B05.V04.A1990161.2018062.hdf"
>> filemodis<-".../GLASS02B06.V04.A2013169.2017128.hdf"
>> gdal_translate(get_subdatasets(filemodis)[10], dst_dataset =
>>         ".../modis.tif")
>> gdal_translate(get_subdatasets(fileavhrr)[8], projwin =
>> c(-180,90,180,50), dst_dataset = ".../avhrr.tif") #ideally I'd only like
>> data north of 50 degrees
>>
>> avhrr<- raster(".../avhrr.tif")
>>
>> #class       : RasterLayer
>> #dimensions  : 800, 7200, 5760000  (nrow, ncol, ncell)
>> #resolution  : 0.05, 0.05  (x, y)
>> #extent      : -180, 180, 50, 90  (xmin, xmax, ymin, ymax)
>> #coord. ref. : +proj=longlat +ellps=clrk66 +no_defs
>> #values      : -32768, 32767  (min, max)
>>
>> modis<- raster(".../modis.tif")
>>
>> #class       : RasterLayer
>> #dimensions  : 3600, 7200, 25920000  (nrow, ncol, ncell)
>> #resolution  : 154.4376, 308.8751  (x, y)
>> #extent   : -20015109, -18903159, 8895604, 10007555  (xmin, xmax, ymin,
>> ymax)
>> #coord. ref. : +proj=sinu +lon_0=0 +x_0=0 +y_0=0 +a=6371007.181
>>     +b=6371007.181 +units=m +no_defs
>> #values      : -32768, 32767  (min, max)
>>
>> Here are things I have tried:
>>
>> 1.) Use the MODIS Reprojection Tool<
>> https://lpdaac.usgs.gov/tools/modis_reprojection_tool>. For whatever
>> reason, this tool seems to think the subdatasets of the MODIS .hdf files
>> are only one tile (the upper left most tile, tile 0,0) and not the global
>> dataset. My understanding is that the MODIS data are global (not in
>> tiles?), so I do not know why the MRT is doing this.
>>
>>
>> 2.) Use the raster package in R.
>>
>> projectedMODIS <- projectRaster(modis,avhrr,method="bilinear")
>>
>> This returns a raster with values that are all NA:
>>
>> class       : RasterLayer
>> dimensions  : 800, 7200, 5760000  (nrow,> ncol, ncell)
>> resolution  : 0.05, 0.05  (x, y)
>> extent      : -180, 180,> 50, 90  (xmin, xmax, ymin, ymax)
>> coord. ref. : +proj=longlat +ellps=clrk66 +no_defs
>> values      : NA, NA  (min, max)
>>
>> 3.) Use the gdalUtils package in R:
>>
>> gdalwarp(srcfile=get_subdatasets(filemodis)[10], dstfile=
>> ".../gdalMODIS_avhrr.tif", s_srs = crs(modis), t_srs =crs(avhrr) )
>>
>> This returns a raster with essentially no spatial extent.
>>
>> gdalMODISavhrr<-raster(".../gdalMODIS_avhrr.tif")
>> #class       : RasterLayer
>> #dimensions  : 357, 12850, 4587450  (nrow, ncol, ncell)
>> #resolution  : 0.02801551, 0.02801573  (x, y)
>> #extent      : -180, 179.9993, 79.99838, 90  (xmin, xmax, ymin, ymax)
>> #coord. ref. : +proj=longlat +ellps=clrk66 +no_defs
>> #values      : -32768, 32767  (min, max)
>>
>> Any ideas on why reprojecting this MODIS data is so difficult?
>>
>>
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>>
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> --
> Dr. Michael Sumner
> Software and Database Engineer
> Australian Antarctic Division
> 203 Channel Highway
> Kingston Tasmania 7050 Australia
>
> --
Dr. Michael Sumner
Software and Database Engineer
Australian Antarctic Division
203 Channel Highway
Kingston Tasmania 7050 Australia

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