Gdal reads data from subdatasets such as HDF and netcdf (multiple datasets)

 

Because the structure of the satellite data (HDF data) is different from that of geotif, you must pay special attention to it when reading the data. Geotif data is generally a file that contains data in multiple bands. While while the modemis, a file contains multiple subdatasets. Gdal. Each subdataset contains multiple band data. In addition, the default compiled gdal does not include support for the modem_data. You need to download the source code for hdf4 and hdf5 separately, and then modify make. the opt file, then compile gdal, and then read and write the data in the MNS. If it is too troublesome, download a compiled project from someone else. There are many open-source projects based on gdal on the Internet. You can search for them.
In the following example, the key gdal reads the data formats of multiple datasets, such as HDF data, netcdf data, and ntif data;

//////////////////////////////////////// ////////////////////////////////////
# Include <stdio. h>
# Include <vector>
# Include <string>
Using namespace STD;

# Include <math. h>
# Include gdal. H"
# Include gdal_priv.h"
# Include ogr_srs_api.h"
# Include cpl_string.h"
# Include cpl_conv.h"
# Pragma comment (Lib, ".. // lib // gdal_ I .lib ")

Int main (INT argc, char * argv [])
{

Gdalallregister ();
Vector <gdaldataset *> datasets;

Char * hdffilename = "D: // fsbdata // v2krns101_20060411_ndvi1_se-Asia // 0001 // 0001_ndv.hdf ";
Gdaldataset * tmpdataset = (gdaldataset *) gdalopen (hdffilename, ga_readonly );

If (tmpdataset = NULL) return 0;
Gdaldriver * driver = tmpdataset-> getdriver ();
String papszmetadata = gdalgetdrivershortname (gdaldriverh) tmpdataset );
Int Index = papszmetadata. find_first_of ("HDF ");
If (index <0)
Index = papszmetadata. find_first_of ("HDF ");
If (INDEX)
{
Char ** subdatasets = gdalgetmetadata (gdaldataseth) tmpdataset, "subdatasets ");
If (cslcount (subdatasets)> 0)
{
Printf ("subdatasets:/N ");
For (INT I = 0; subdatasets [I]! = NULL; I ++)
{
If (I % 2 = 0)
{
String tmpstr = string (subdatasets [I]);
Tmpstr = tmpstr. substr (tmpstr. find_first_of ("=") + 1 );
Const char * tmpfilename = tmpstr. c_str ();
Gdaldataset * tmpdt = (gdaldataset *) gdalopen (tmpfilename, ga_readonly );
If (tmpdt)
{
Datasets. push_back (tmpdt );
}
}
}
}
Else
{
Int bandcount = tmpdataset-> getrastercount ();
If (bandcount> 0)
{
Gdalrasterband * poband = tmpdataset-> getrasterband (1 );
}
Printf ("It contains % d bands! /N ", bandcount );
}
}
If (! Datasets. Empty ())
{
Int COUNT = datasets. Size ();
Int bandcount = 0;
For (INT I = 0; I <count; I ++)
{
Bandcount + = datasets [I]-> getrastercount ();
If (datasets [I]-> getrastercount ()> 0)
{
Gdalrasterband * poband = datasets [I]-> getrasterband (1 );
}
}
Printf ("It contains % d bands! /N ", bandcount );
For (I = 0; I <count; I ++)
{
Delete datasets [I];
Datasets [I] = NULL;
}
Datasets. Reserve (0 );
}

Delete tmpdataset;
Delete driver;
Printf ("It's OK! Please enter any key! /N ");
Return 0;
}