[gdal-dev] New OGR driver: Imageset

Even Rouault even.rouault at mines-paris.org
Mon Jul 23 03:04:02 PDT 2012

Le lundi 23 juillet 2012 11:27:01, Tamas Szekeres a écrit :
> Hi Even,
> I just want to use the directory name to define the connection to the
> images, we could also provide to scan the files in subdirectories if
> needed.

Do you imagine something like :

ogrinfo my_directory_with_images


ogrinfo IMAGESET:my_directory_with_images

The first syntax is convenient, but in the case the user isn't specifically 
interested in this driver, it could create performance problems if it 
GDALOpen() each file in the specified directory. There also could be a 
"competition" problem with, let's say, the shapefile or MITAB driver that also 
accept directory names : if the directory contains JPEG images, and also a 
shapefile or a .mif/.tab file, the new driver will not be used.

> I would prefer to have a new driver not just an offline tool for
> creating OGR datasets, in this case many existing applications (like
> MapServer) would be capable to utilize this feature.

Seems reasonable

> I could imagine a driver configuration file to specify which driver should
> be used for a particular image format

GDALOpen() should do it for you automatically. Unless you intend to have a 
list of known extensions, ".jpg", ".jpeg", ".tif", ".tiff" to avoid useless 
GDALOpen() attempts.

> and where the specific information is
> located, I don't require to harmonize the metadata structure at this time.

That could be an opportunity to do so. But you could just try exploring the 
contents of GetMetadata(NULL) and GetMetadata("EXIF") without caring which 
driver exposes the stuff in which domain. The code for both driver is the same 
and is located in gcore/gdalexif.cpp

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