Re: Help with storing spatial (map coordinates) data?

Hi Brent,

Excellent advice, thanks for taking the time with what must be a fairly
newbie question in GIS terms.

I appreciate your help.

Cheers

John

Brent Wood wrote:
> On Tue, 13 Jun 2006, John Tregea wrote:
>
>
>> Thanks Brent,
>>
>> I will be cautious in my approach. The public schema is the place that I
>> wanted to use to store the geometry attributes, so from your points,
>> that sounds like the best place. The other schemas contain controlled
>> (security) information in proprietary data structures so I that was my
>> reluctance to modify those tables with the necessary geometry functions,
>> types etc.
>>
>>
>
> Sounds eminently sensible :-)
>
> One point you might note, the AddGeometryColumn() function does two
> things. It adds a geometry column of the appropriate projection & type to
> the specified table. It also writes a metadata record to the
> geometry_columns table. This is where many application look to find tables
> with geometries.
>
> If you create a view on a table with a geometry column, or create a table
> with a geometry column without using the AddGeometryColumn() function (eg:
> create table foo1 as select * from foo0;), then some applications will not
> recognise the table or view as a "GIS" table.
>
> If you are adding geometries to tables via views, which it sounds like you
> may be doing, you may need to manually insert the appropriate data into
> the geometry_columns table to be fully compliant with the OGC specs &
> PostGIS implementation.
>
> If you create such a geometry table or view & the GIS package you are
> using fails to make it available as a data source, this is almost
> certainly why :-)
>
> Cheers,
>
>   Brent
>
>
>