[gdal-dev] subdatasets not read in a HDF file

Mon Oct 24 07:52:57 EDT 2011

Hi Joaquim!

I'm curious why do you want to read cnt_pt_col and cnt_pt_row from a 
SeaWiFS file?

These dataset (1D vectors, actually) only contains indexes of rows and 
columns for which latitude, longitude grids are given. And you can read 
lat/lon from GCPs. Or do you also feel that only ~100 GCPs are not enough ?

I'm working with MODIS data and in the Arctic warping results look ugly 
sometimes. I was thinking if I should try to get lat/lon grids from an 
HDF file and increase number of GCPs.

Anton

On 10/23/2011 08:54 PM, Joaquim Luis wrote:
> Etienne,
>
> 1) Manage to attach the file (zipped) to the just opened ticket.
>
> 2) Unfortunately it doesn't work. It says the usual
>
> C:\SVN\mironeWC>gdalinfo "NETCDF:S1998031140424.L2_MLAC_OC.x.hdf:longitude"
> ERROR 4: `NETCDF:S1998031140424.L2_MLAC_OC.x.hdf:longitude' does not
> exist in the file system,
>
> Note that I built GDAL with netcdf4 that on Windows is always linked
> against HDF.
>
> Joaquim
>
>
>
>> 1) Not sure, but give it a try! If not, put it somewhere accessible on
>> the web. You should definitively create a ticket for this.
>>
>> 2)
>> netcdf supports HDF4 if it was configured for hdf4 support.
>>
>> In that case, to force the netcdf driver you would have to use
>> "NETCDF:filename:subdataset", or else the HDF4 driver will open it
>> pick it up.
>>
>> Etienne
>>
>> On Sat, Oct 22, 2011 at 9:57 AM, Joaquim Luis <jluis at ualg.pt
>> <mailto:jluis at ualg.pt>> wrote:
>>
>>     Hi,
>>
>>     I'm having troubles reading a SeaWifs L2 hdf file due to a bug in
>>     the hdf driver. The problem here is that not all Subdatasets are
>>     read.
>>     Below is the list givem by gdalinfo, which lacks 2 subdatasets: the
>>     cntl_pt_cols & cntl_pt_rows
>>     To prove I attach a little screencapture of "HDF Explorer".
>>
>>     Now I have two questions.
>>
>>     1- The hdf file in question is relatively small (1.2 Mb). Can I
>>     attach it to a ticket?
>>
>>     2- If I build GDAL with netCDF4, can I force the reading of this
>>     file with the netCDF driver? And if yes, how?
>>
>>     Thanks
>>
>>     Joaquim
>>
>>
>>
>>
>>     Subdatasets:
>>     SUBDATASET_1_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":11
>>     SUBDATASET_1_DESC=[391x78] longitude (32-bit floating-point)
>>     SUBDATASET_2_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":12
>>     SUBDATASET_2_DESC=[391x78] latitude (32-bit floating-point)
>>     SUBDATASET_3_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":13
>>     SUBDATASET_3_DESC=[391x78] Rrs_412 (16-bit integer)
>>     SUBDATASET_4_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":14
>>     SUBDATASET_4_DESC=[391x78] Rrs_443 (16-bit integer)
>>     SUBDATASET_5_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":15
>>     SUBDATASET_5_DESC=[391x78] Rrs_490 (16-bit integer)
>>     SUBDATASET_6_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":16
>>     SUBDATASET_6_DESC=[391x78] Rrs_510 (16-bit integer)
>>     SUBDATASET_7_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":17
>>     SUBDATASET_7_DESC=[391x78] Rrs_555 (16-bit integer)
>>     SUBDATASET_8_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":18
>>     SUBDATASET_8_DESC=[391x78] Rrs_670 (16-bit integer)
>>     SUBDATASET_9_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":19
>>     SUBDATASET_9_DESC=[391x78] chlor_a (32-bit floating-point)
>>     SUBDATASET_10_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":20
>>     SUBDATASET_10_DESC=[391x78] Kd_490 (16-bit integer)
>>     SUBDATASET_11_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":21
>>     SUBDATASET_11_DESC=[391x78] pic (16-bit integer)
>>     SUBDATASET_12_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":22
>>     SUBDATASET_12_DESC=[391x78] poc (16-bit integer)
>>     SUBDATASET_13_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":23
>>     SUBDATASET_13_DESC=[391x78] cdom_index (16-bit integer)
>>     SUBDATASET_14_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":24
>>     SUBDATASET_14_DESC=[391x78] par (16-bit integer)
>>     SUBDATASET_15_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":25
>>     SUBDATASET_15_DESC=[391x78] l2_flags (32-bit integer)
>>     SUBDATASET_16_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":34
>>     SUBDATASET_16_DESC=[391x3] orb_vec (32-bit floating-point)
>>     SUBDATASET_17_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":35
>>     SUBDATASET_17_DESC=[391x3] sun_ref (32-bit floating-point)
>>     SUBDATASET_18_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":36
>>     SUBDATASET_18_DESC=[391x3] att_ang (32-bit floating-point)
>>     SUBDATASET_19_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":37
>>     SUBDATASET_19_DESC=[391x3x3] sen_mat (32-bit floating-point)
>>     SUBDATASET_20_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":38
>>     SUBDATASET_20_DESC=[391x6] scan_ell (32-bit floating-point)
>>     SUBDATASET_21_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":39
>>     SUBDATASET_21_DESC=[391x8] nflag (32-bit integer)
>>     SUBDATASET_22_NAME=HDF4_SDS:SEAWIFS_L2:"S1998031140424.L2_MLAC_OC.x.hdf":42
>>     SUBDATASET_22_DESC=[20x2] tilt_ranges (16-bit integer)
>>     Corner Coordinates:
>>
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>>
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