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I am working with the Modis version6 NDVI/EVI 16 day composite dataset (MOD13Q1). I am developing a automated algorithm to download, aggregate, and processes the dataset. Therefore, I do not want to use the MODIS specific tools, but use the gdal library to reproject the dataset to UTM 13N. However, I have found conflicting information regarding the correct projection information. spatialreference.org has several different projects:

http://spatialreference.org/ref/?search=MODIS

And here is the gdalsrsinfo for one of the HDF4 datasets:

gdalsrsinfo 'HDF4_EOS:EOS_GRID:"MOD13Q1.A2017049.h10v04.005.2017066041938.hdf":MODIS_Grid_16DAY_250m_500m_VI:250m 16 days NDVI'

PROJ.4 : '+proj=sinu +lon_0=0 +x_0=0 +y_0=0 +a=6371007.181 +b=6371007.181 +units=m +no_defs '

OGC WKT :
PROJCS["unnamed",
GEOGCS["Unknown datum based upon the custom spheroid",
    DATUM["Not specified (based on custom spheroid)",
        SPHEROID["Custom spheroid",6371007.181,0]],
    PRIMEM["Greenwich",0],
    UNIT["degree",0.0174532925199433]],
PROJECTION["Sinusoidal"],
PARAMETER["longitude_of_center",0],
PARAMETER["false_easting",0],
PARAMETER["false_northing",0],
UNIT["Meter",1]]

Can anyone provide some clarification to the correct SRID information?

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you can use my python script to download the MODIS data. To reproject the MODIS data, you can quite easily use gdalwarp as follows:

gdalwarp -t_srs "EPSG:25829" \
    'HDF4_EOS:EOS_GRID:"'$fname'":MODIS_Grid_16DAY_1km_VI:1 km 16 days NDVI' stuff.tif

(I set $fname to the MODIS filename so that it doesn't look that horrible, and I used UTM29N/ETRS89 as my destination projection, as I had a h17v04 tile lying around). My current version of GDAL picks up the MODIS projection, but in case yours doesn't, the one you want is

'+proj=sinu +R=6371007.181 +nadgrids=@null +wktext'

which you would enforce by using the -s_srs option in gdalwarp. You can extend my code to do the reprojection and so on in Python, these notes might be useful.

  • Thanks for all the great references Jose! Currently I am using pymodis to automate the downloading processes, but I will take a look at your script as well! I am a still a bit confused with the projection though. It looks like the proj4 string you have is equivalent to this one. However, when I do gdalsrsinfo on my data, it gives an alternative proj4, so won't gdal use the one I posted in my question? Are the two equivalent or should I force the one you posted with the -s_srs? – Rowan_Gaffney Mar 21 '17 at 17:12
  • @Rowan_Gaffney That was a typo, c&p from your answer instead of from my code ;-P. Have now updated – Jose Mar 21 '17 at 18:10

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