hdfgd issue when reading MODIS mcd12c1 coordinates (or the way to get the coordinates of hdf-eos data)

I used the code below to try to get the grid information of MODIS MCD12C1 data. The data format is hdf-eos. But grid_id always equals to -1. Does anyone know why or share another way with me to read the coordinates of hdf-eos data. Thank you!!!

FILE_NAME='MCD12C1.A2001001.051.2014274170618.hdf'
GRID_NAME='GeoGrid'
file_id = hdfgd('open', FILE_NAME, 'rdonly')
grid_id = hdfgd('attach', file_id, GRID_NAME)

Answer 1

[Rong Yu]

Figured it out.

GRID_NAME should be the exact one from the metadata, which can be achieved by hdfinfo.

For example,

fileinfo = hdfinfo('MCD12C1.A2009001.051.2013164180520.hdf');

In fileinfo>attributes>'StructMetadata.0', there is GridName.