Can't build overviews for HDF4 and HDF5 with or without subdatasets

[gaopeng]

Building overviews fails on HDF4 images with or without subdatasets.

[rprinceley]

Adding myself to CC.

[gaopeng]

The same problem exits for HDF5.

[antonio]

Replying to gaopeng:

The same problem exits for HDF5.

Please provide more info:

• platform, GDAL version (confirm 1.6.0?)
• can you provide the output of

  $ gdalinfo --formats
  

• are you trying to build overviews programmatically or via gdaladdo?
• can you provide a test dataset to reproduce the issue?
• can you provide a sample code/command line to reproduce the issue?

But for the known issue with old libtiff versions I can build overviews on HDF5 files without problems with GDAL >= 1.5.2.

[warmerdam]

I have implemented (r16731) core support for overviews on subdatasets (in GDALDefaultOverviews, and GDALPamDataset) and made adjustments to the NITF, HDF4, HDF5, and NetCDF drivers to utilize this. The key is to ensure the physical and subdataset names are properly set on the GDALPamDataset, and to call oOvManager.Initialize() *after* TryLoadXML(), and to pass ":::VIRTUAL:::" in place of the filename. The overview file name is stored in metadata (same as for proxy overviews), and an overview filename is allocated as needed when overviews are built.

A small test of this capability has been added to the hdf5.py test script (r16732).

All changes are currently in trunk. I do not think these changes are suitable to retrofit into the 1.6 branch.

A significant portion of the work on the listed drivers was just to get subdataset metadata support working properly.

[warmerdam]

Migrated to 1.6-esri branch as part of r17187.