[GRASS-user] using grass on rasters without converting?

[Markus Neteler]

On Thu, Oct 30, 2008 at 6:57 PM, Glynn Clements
<glynn at gclements.plus.com> wrote:
> Markus Neteler wrote:
>> In theory, r.external might also accept WMS since GDAL does it:
>> http://www.gdal.org/frmt_wms.html
>
>> # this gets stuck:
>> d.rast gdal_wms
>>    0%
>>
>> strace shows
>> ...
>> select(8, [6 7], [], [], {0, 100000})   = 0 (Timeout)
>> poll([{fd=6, events=POLLIN|POLLPRI}], 1, 0) = 0
>> poll([{fd=7, events=POLLIN|POLLPRI}], 1, 0) = 0
>> select(8, [6 7], [], [], {0, 100000})   = 0 (Timeout)
>> ...
>>
>> Maybe some update magic is needed internally (but maybe
>> I am exaggerating right now...).
>
> Maybe GDAL can't handle skipping rows for WMS? Due to the region
> mapping, GRASS typically doesn't request rows sequentially (it may
> skip rows, or request them in an arbitrary order, even reverse order).

Here an offlist answer from Frank (fwd with permission):

On Thu, Oct 30, 2008 at 7:34 PM, Frank Warmerdam wrote:
> I'm not too familiar with the WMS driver.  But if it doesn't support
> skipping rows then it is a bug and should be fixed.  To file a ticket on
> this issue it would be helpful if a demonstration of the problem could
> be boiled down to a small C/C++ program or Python script just depending
> on GDAL.
>
> Adam Nowaki is the main author of the WMS driver.

Unfortunately I am not skilled enough in Python to write down the
requested test case.

Markus