[Liblas-devel] Specification for point dimensionality

[Howard Butler]

On Mar 12, 2010, at 6:31 AM, Mike Grant wrote:

> Hi Howard,
> 
> On 25/02/10 16:10, Howard Butler wrote:
>> I would like to
>> propose that we provide a liblas.org VLR record that contains an XML
>> file to describe the dimensions, their sizes, if they are used, etc.
> [snip]
>> I propose each entry in the file have the following attributes:
> 
> Not sure if LAS mandates a global endian format, but it'd be good to
> include that if not.

All three of the specs say "All data is in little-endian format."

> 
>> All this would be properly namespaced XML (liblas.org or something)
>> along with whatever we can find for standards such as those for
>> describing data types, etc.  Maybe there's an existing standard for
>> something like this already, I don't know.
> 
> I've come across two things that might be worth looking at - they're not
> directly usable here, but they may provide some guidance/ideas:
> 
> http://www.gdal.org/ogr/drv_vrt.html (also
> http://www.gdal.org/gdal_vrttut.html)
>  - GDAL's XML format for describing data (see the fields section)

Heh, VRT's actually my counter-example.  It's home-grown, it doesn't have a schema to validate against, it can't live in a namespace, and it makes up its own names for everything.

> 
> http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.4/ch03s05.html
>  - CF Conventions for netCDF data (bitfields section)

ooh, I hate netCDF's approach :)  

> On a vaguely related note, it'd be nice to have a VLR XML (ISO) that
> described the dataset for archival and metadata purposes.  

Have an example?