[Qgis-user] QField: recommendations for aerial basemap preparation?

[Matthias Kuhn]

Hi,

There is a gis stackexchange question open regarding this which has some
good inputs to consider.

https://gis.stackexchange.com/questions/309379/choosing-raster-format-for-qfield

There is also some information in the QField documentation regarding
this topic (although that could benefit from some improvements from your
findings, there's an edit on github link at the bottom of the page ;) )

https://www.qfield.org/docs/project-management/dataformat.html#raster-data

Best regards

Matthias

On 3/24/19 9:37 PM, Bernd Vogelgesang wrote:
> Hi,
>
> I need an aerial basemap for my QField-project to be able to locate
> positions. As QField has not the ability to navigate to a point or
> indicate the direction of movement, provided only with a topographic
> basemap, I'm stumbling through the forest and have a hard time finding
> the positions.
>
> The project area is huge, around 400 square kilometers! I have a Mrsid
> file of the area of 1.6 GB with 20 centimeter resolution,
> transformed with gdal_translate to tiff is 42.5 GB,
> compressed with gdal_transform with jped-compression 50% 968 MB,
> resampled to 40cm resolution and 50% jpeg has 295 MB
>
> I used the QField sync plugin to generate a baselayer in gpgk-format
> from this ,which has 540 MB with 40 cm resolution.
>
> Unfortunately, on the tablet, the baselayer is loading so slow, that it
> is impossible to work with it. Each redraw takes around 10 seconds in
> the small scale, rising to infinity in higher scales.
>
> I wonder if there are other approaches recommendable, for example
> splitting the image into separate layers for bigger regions, which I
> could then turn on and off, or if I should prepare the image apart from
> using the plugins converter to gpkg.
>
> Due to the enourmous amount of time needed to process the image on the
> PC, a trial-and-error approach seems not to be feasable, so I ask you if
> someone can recommend an approach for such a huge beast.
>
>
> Thanx in advance,
>
> Bernd
>
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-- 
Matthias Kuhn
matthias at opengis.ch <mailto:matthias at opengis.ch>
+41 (0)76 435 67 63 <tel:+41764356763>
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