[postgis-devel] Regular raster blocking (was: Real extent feature lost after metadata as views)

[Mateusz Loskot]

On 6 December 2012 20:17, Pierre Racine <Pierre.Racine at sbf.ulaval.ca> wrote:
>> > This constraint ensures that all tile are of the same size and hence, do not
>> > overlap and do not leave gaps in the coverage.
>>
>> > I think there is no need any more to ensure that "All tiles must be non-
>> > overlapping" or "There must be no gap" since both are ensured by the
>> > conjunction of the three conditions. Any counter example?
>>
>> Well this is false.. It is not because tiles are of the same size that they cover all
>> the extent without leaving gaps or overlaps.
>
> Well I come back on this... This was not false. This was true.
> If all upper left corners are aligned on a grid defined by the upper left corner of the extent
> AND the block sizes, AND all tiles are the same size as the block sizes,
> THEN there should be no gaps,
> AND we could allow missing tiles (because we do not have to check for gaps).

Yes, that's correct.

Best regards,
--
Mateusz Loskot, http://mateusz.loskot.net