[GRASS-dev] Rendering of vector layers can be slow

[Moritz Lennert]

On 08/08/16 11:27, Blumentrath, Stefan wrote:
> Hi,
>
>
>
> At the moment I am fixing and quality checking relatively larger vector
> datasets with some 100k areas, of which some are quite complex (sea area
> / coast line). That requires visual inspection of the data and thus
> repeated rendering at different scales.
>
>
>
> In this context I am struggling with rendering speed in GRASS 7.0.4. I
> am working on a relatively powerful server with local data in native
> GRASS format.

Vector rendering speed has been an issue and has been discussed before, 
a long time ago [1, 2], but I don't remember if there was much follow-up 
in terms of changing d.vect. The issue was mentioned again later [3]. 
Also see the debate in [4], but this was not explicitely about vector 
rendering.

>
>
>
> In comparison, QGIS on my local laptop renders the same data from
> PostGIS significantly faster, even when fetched through a WLAN connection...

AFAIK, QGIS now has multithreaded rendering. I don't know if this 
creates the difference. Also watch out: QGIS starts rendering parts of 
the layer very quickly, but you have to compare the time it takes for 
both to render the entire layer.

>
>
>
> Any possibilities to speed up rendering of vector maps?


Maybe some of the ideas Glynn advanced in the response to [2] are still 
relevant. I don't think there have been any changes related to these 
ideas to lib/gis/plot.c since that discussion.

I agree that this would probably be of use, but I guess it never has 
been an itch strong enough to provoke those who have the knowledge into 
action. :-)

Moritz




[1] https://lists.osgeo.org/pipermail/grass-dev/2006-August/025250.html
[2] https://lists.osgeo.org/pipermail/grass-dev/2006-September/025858.html
[3] https://lists.osgeo.org/pipermail/grass-dev/2012-August/059178.html
[4] https://trac.osgeo.org/grass/ticket/2033