[gdal-dev] opening an S-57 dataset directory

[Yilmaz Arslanoglu]

Ok Frank, thank you very much for the answer.

Actually, under the "gdal/frmts/iso8211" directory,
I found the class called "DDFModule" which can open
both individual ENC files (*.000) and ENC catalogue files (*.031)

Now I use this class to open the catalogue file, get the paths of all relevant
files that I need (according to their coverage, since catalogue file
contains this information also),
and only open these files as OGR datasets.

However, if there is no catalogue file, I recursively search the given
directory,
and I need to open (load as OGR dataset) all ENC files that are found, in order
to check their coverages.

Is there a way to check the file coverage without loading the file?
(since I'm dealing with around a hunred of them, this operation takes minutes)


On Sun, Oct 18, 2009 at 4:49 AM, Frank Warmerdam <warmerdam at pobox.com> wrote:
> Yilmaz Arslanoglu wrote:
>>
>> Hello everybody;
>>
>> I was just wondering whether there is a specific directory structure
>> that needs to be followed
>> in order to open an S-57 file collection by giving a single directory
>> path, instead of a file with a .000 extension.
>>
>> I'm asking because, according to the following statement from OGR IHO
>> S-57 (ENC) Driver
>> documentation, we would be able to pass a directory name.
>>
>>>> An S-57 dataset can be a directory (in which case all S-57 files in the
>>>> directory are selected),
>>>> an S-57 catalog file (in which case all files referred to from the
>>>> catalog are selected) or an individual S-57 data file.
>
> Yilmaz,
>
> On review of the code it appears the documentation is wrong and
> multiple file access was never fully implemented.  I have updated
> the documentation accordingly.
>
>> However, when I try to open with a directory name using
>> "OGRSFDriverRegistrar::Open", I get an error.
>>
>> As another question:
>>
>>>> S-57 update files contain information on how to update a distributed
>>>> S-57 base data file.
>>>> The base files normally have the extension .000 while the update files
>>>> have extensions like .001, .002 and so on.
>>>> The S-57 reader will normally read and apply all updates files to the in
>>>> memory version of the base file on the fly.
>>>> The feature data provided to the application therefore includes all the
>>>> updates.
>>
>> So how OGR decides to look for the extension files? Because as far as
>> I can see, ENC catalogues may come
>> with different directory structures, where in some of them all update
>> files accompany the original one in the same directory,
>> however they may also come in another directory in some others.
>
> The driver will only find update files if they are in the same directory
> as the .000 file, have names like .001, etc and a shared basename.
>
> Best regards,
> --
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | Geospatial Programmer for Rent
>
>