[Scilab-users] Headless graphics in scilab: time & memory issues

[Stéphane Mottelet]

Hello Antoine,

Exporting in headless mode (all drivers but the default "Rec") is 
fundamentally different from the default "Rec" mode where graphics are 
actually rendered on screen on a joGL Canvas. In this case there is 
virtually no overhead when exporting this Canvas to a bitmap image 
format (png,jpeg,gif,...). In headless mode the rendering cannot use 
joGL and there is the same overhead as when you try to export a figure 
to a vectorial format (svg,pdf,eps) :

nx=4000;
ny=300;
nc=100;

x=1:nx;
y=[1:ny].';
z=(y*x);

driver Rec
h=scf();
h.color_map=hotcolormap(nc);
Sgrayplot(x,y,z.');
xs2pdf(h,"screen.pdf")

at line    13 of executed file /Users/mottelet/Desktop/xend_test.sce

xs2pdf: Unable to create export file, not enough memory. Decreasing the 
number of elements or the size of the figure should fix this error.

S.

Le 03/12/2020 à 09:48, Antoine Monmayrant a écrit :
>
> Hello all,
>
> In these days of remote working, I need to use again scilab in 
> headless mode to generate graphics.
>
> In other words, I connect  in command line only to a remote server 
> where scilab is installed and I want it to generate graphics using a 
> combination of driver, xinit and xend.
>
> There seems to be some issues with driver/xinit/xend: huge memory 
> overhead and long computation time that makes it impossible to 
> generate some plots in headless mode.
>
> For example, a simple Sgrayplot that takes ~1 second to plot and save 
> to a png in normal mode takes more than 200 seconds and huge amount of 
> ram in headless mode (see attached test script).
>
> I also have some plots that works without a problem in normal mode, 
> but fail in headless mode because of some memory limitation:
>
>     xend: An error occurred: Unable to create export file, not enough
>     memory. Decreasing the number of elements or the size of the
>     figure should fix this error.
>
> Is there a way to get around these problems?
>
> Thanks for your help,
>
> Antoine
>
>
>
>
>
>
>
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-- 
Stéphane Mottelet
Ingénieur de recherche
EA 4297 Transformations Intégrées de la Matière Renouvelable
Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
Tel : +33(0)344234688
http://www.utc.fr/~mottelet

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