[Qgis-user] Mosaic Datasets and Raster Catalogs in qGIS

[Richard Greenwood]

As Zoltan suggested, a .vrt is a good approach, but you will want overviews
also so that you can zoom out. You can create overviews (aka pyramids) of
.vrt files.

Personally, I'd suggest creating one, or a few, big GeoTIFFs with internal
or external overviews. I have a 4,400 sq mile (1,140,000 hectare) area of 3
inch and 6 inch RGB imagery that's in 8 files with with JPEG YCbCr
compression. Including overviews, the total size is 150GB and the
performance is excellent. Check out cloud optimized geotiffs. Despite the
name, they provide great performance and compression on local file systems
(and are obviously cloud ready if/when you need to server them from cloud
storage).

On Fri, Jan 14, 2022 at 1:50 PM Zoltan <zoltans at geograph.co.za> wrote:

> Hi Jason,
> You just need to create a VRT.
> The vrt is just that:  a virtual raster table.
> Fiddle with the options and notice that you can mix rasters that have
> differing projection.
>
> Test out on maybe a 100 or so Raster files and when you get the feel for
> it,  dump the lot in. I've had >5000 files in  one with no hassles.
> Note that if you output your vrt file into the same folder as your
> rasters, when you recreate your vrt, it will read in your old one and go
> into a loop.
> I logged this as a bug and was told unceremoniously that it was not a bug.
>
> Btw, when you first load your vrt into qgis, have rendering turned off.
> Then set your zoom display scales before turning rendering on again. This
> will stop qgis from trying to display all your tasters if you happen to be
> zoomed out too far.
>
> Have fun, it works well.
>
> Regards
> Zoltan
>
> Sent from BlueMail <http://www.bluemail.me/r?b=10698>
> On 14 Jan 2022, at 21:45, Jason Aleksi <jason.aleski at gmail.com> wrote:
>>
>> I am trying to add imagery in qGIS.  In ArcMap, I had to create a Mosaic
>> Dataset, then a Raster Catalog.  It tooks days to create due to the large
>> files and quantity of files.  I have 6 inch imagery of a county in a
>> folder.  The GeoTIFFs are about 308GB in size and approx 6,610 files (TIF
>> and TIFW).  When I attempt to create a raster layer, it will only pull in
>> 100 images.
>>
>> Will I have to create 305 Layers with 100 images each?  Or is there a
>> better way?  I'm at a loss for terms to even search for.  I feel I've
>> exhausted Google!  If there is a better way, could you possibly point me in
>> the right direction?
>>
>> FTW: I also have MrSID Tiles and Composites, in a separate directory.
>>
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-- 
Richard W. Greenwood
www.greenwoodmap.com
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