[Qgis-user] Metis and creating pyramids

[Micha Silver]

Hello Maciej:


Maciej Sieczka wrote:

> Micha Silver pisze:
>> I can't seem to create pyramids with 0.11. Neither on Windows nor on
>>  Ubuntu.
>>
>>
>
> Regarding rendering perfomance - try to create a TIFF without tiles
> (gdal_translate -co "TILED=NO" -co "BLOCKYSIZE=1"). At least for me,
Many thanks! Your suggestion certainly helped. It seems that giving the 
explicit "TILED=NO" option creates a stripped tiff that loads *much* 
faster. And zooming was very good also.  (BTW I didn't use BLOCKYSIZE=1 
as that gave an error ).
In the gdal_translate docs it says that the default (with no TILED= 
option) is stripped tiff, but that doesn't seem to be the case? When I 
created tiffs with no TILED option they loaded quite slowly. Then I 
added the TILED=YES, and still the images loaded and zoomed slowly. 
TILED=NO gave a dramatic improvement.

>
> Anybody knows why QGIS renders tiled rasters without pyramids so slow?
>
>> But when I try to create pyramids, it seems to be working for a
>> while, then the process ends. But there is no change to the file, and
>> if I reopen the properties window to the Pyramids tab, all pixel
>> levels are still marked in red. The tiff's are in my homedir so, yes,
>> I have write access.
>>
>> Can anyone else confirm this?
>
> For me building pyramids in QGIS works OK.
>
Furthermore, I see that with stripped, non-tiled tiff's, I can create 
pyramids in QGIS with no problem. Previously, when I used TILED=YES in 
gdal_translate, the Create Pyramids didn't do anything. I suppose you 
wouldn't want or need both tiled tiff and pyramids so maybe it's a 
feature that zoom levels are not duplicated?
> Maciek
>
Thanks,
Micha