[gdal-dev] Follow on to the "ISO Metadata" post

[Tim Crook]

Yes, it had occurred to me that XSLT would be a flexible way of handling a lot of the metadata mappings.

From: Damian Dixon 
Sent: Monday, October 26, 2015 8:36 AM
To: Tim Crook 
Cc: doug_newcomb at fws.gov ; gdal dev 
Subject: Re: Follow on to the "ISO Metadata" post

Hi Tim,

Personally I would not use ISO 19115-1 as an internal format.

There are not a huge number of data formats/products that store metadata as XML out of the box. When they do store metadata it is usually specific to the data and data product (regardless of how the metadata is stored).

There have been attempts at adding metadata alongside data products such as UK MOD profile of IS0 19115 (MOD profile has problems). The French equivalent of the MOD have for a number of years mandated a metadata format alongside all data products used by them (wish I could find the actual standard for the metadata).

The biggest problem is actually mapping from data/'data product' metadata to the target metadata specification.

Just to highlight how much a problem the mapping of fields from one metadata format to another is; we have been arguing off and on for more than a year internally about the meaning of dates and which date should be in which field. Two of our big customers do not agree on the meaning of some of the source data date fields and the mappings we have done.

I believe ESRI have their own internal metadata format that they provide a tool to translate to other XML metadata specifications.

Where I work I have been pushing a per data/'data product' format that is XML based that uses tag value pairs. The tags would basically be a dump of all available information and specific to each data/'data product'. A set of XSLT scripts would then translate the information to what ever metadata standard you wanted to use and if you needed to modify the mapping you could change the XSLT script for that data/'data product'.

We have found that hard-coding the mapping is too costly to maintain and very difficult to get right.

Probably not the answer you are looking for.

Regards
Damian


On 22 October 2015 at 13:29, Tim Crook <tim.crook at sympatico.ca> wrote:

  Hello Doug and Damian.

  I saw your post about ISO 19103, ISO 19115 and  ISO 19115-1. I am starting to look at ticket #3549 (https://trac.osgeo.org/gdal/ticket/3549). This ticket is a specific problem for metadata translation for image transformations to the PCIDSK format. The ticket references JPEG and TIFF.

  The first thing I thought of was when I saw your posts was mapping the XML metadata from different sources into an internal format to GDAL, then passing through the information for mapping to the destination format. I suppose there are some image source formats that don't use XML to store their metadata, so this would require additional handling.

  I suppose the internal format to GDAL could be XML in the ISO 19115-1 format.

  Am I completely off base here? 

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