[gdal-dev] BigTIFF Overviews ( OVR files )

[David Fogel]

Hi Christopher,

And so I shall experiment with the GDAL_CACHEMAX setting.  Perhaps I
can post back on that before the end of the day here (US West Coast;
PST);

Thanks.
= David

On Tue, Feb 9, 2010 at 2:13 PM, Christopher Schmidt
<crschmidt at metacarta.com> wrote:
> On Tue, Feb 09, 2010 at 01:57:26PM -0800, David Fogel wrote:
>> Hi:
>>
>> In the process of moving data into GeoTIFF, I am re-creating pyramids
>> (OVR files).  The good news: It takes fewer than ten minutes to create
>> an LZW Horizontal Differenced compressed 3.5 GB file on a Windows 7
>> box using GDAL 1.70+ ( via Tamas Szekeres site; 64-bit precompiled ).
>>
>> The OVR files are problematic.  Using gdal_translate, I can resize by
>> 50% in less than ten minutes.  Using gdaladdo, the first layer ( "2" )
>> takes hours to complete.
>>
>> This is for SRTM 16-bit data.  It appears that something is amiss.
>>
>> Tips and tricks?
>
> One piece of advice; I find that adding overlays is often significantly
> helped by increasing the GDAL_CACHEMAX setting.
>
> gdaladdo --config GDAL_CACHEMAX 800 file.tif 2 4 8 16 32 64
>
> 800 is MB of memory; as a result, it probably makes sense to limit this
> if your platform is low on free RAM.
>
> Regards,
> --
> Christopher Schmidt
> MetaCarta
>