Opened 10 years ago

Closed 7 years ago

#4425 closed enhancement (wontfix)

support more HDF4 files by dropping requirement of "Signature" attribute

Reported by: andreash Owned by: warmerdam
Priority: normal Milestone:
Component: GDAL_Raster Version: unspecified
Severity: normal Keywords: HDF4
Cc:

Description

Hi,

I noticed that when I create a HDF4 ScientificDataSet file directly with the HDF4-API (without GDAL), and I add the attributes TransformationMatrix, AREA_OR_POINT and Projection, to the file, GDAL still refuses to read the georeferencing from the file. Once I additionally add an attribute Signature reading "Created with GDAL (http://www.remotesensing.org/gdal/)", GDAL does read the georeferencing correctly.

I personally find this behaviour very strange. My suggestion:

In hdf4dataset.cpp, line 743, in the final else case, before setting the dataset type to UNKNOWN, check if the required attributes are present and if yes, set the dataset type to GDAL_HDF4

Change History (5)

comment:1 Changed 10 years ago by andreash

Type: defectenhancement

comment:2 Changed 10 years ago by warmerdam

I don't really see the problem with the current behavior.

If other applications want to set GDAL metadata they will need to set the GDAL signature as well.

comment:3 Changed 10 years ago by warmerdam

Component: defaultGDAL_Raster
Keywords: HDF4 added

comment:4 Changed 10 years ago by andreash

From my point of view, setting an attribute to "Created with GDAL" if the file was actually created with XYZ is not correct and misleading. I see a difference between "Software used to create the file" and "Metadata conventions followed in the file". If I want to create HDF4 files with a home-grown application and want these files to be read correctly by GDAL tools/library, I should not be forced to claim that I created the files with GDAL if I actually didn't.

But again, this is just my pont of view, and I'm new to GDAL and how things are being done here.

comment:5 Changed 7 years ago by Jukka Rahkonen

Resolution: wontfix
Status: newclosed

If I understand it right the signature is there for advertising that the file contains GDAL style metadata. Perhaps the text of the signature "Created with GDAL (http://www.remotesensing.org/gdal/)" is not the best possible because also other programs can also write GDAL style metadata and the web address has been invalid for some years. However, I do not believe that updating the title into "Contains GDAL style metadata" would make anybody very much happier. See also related issue #4426.

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