I am running the Annual Irradiance recipe in Python only and i was trying out Accelerad to speed up the simulation. So far everything is working and my simulation speeds up around 4x.
But i get kind of blurry results when using Accelerad. So i simulate an area with a resolution of 1cm, but i get these dots with completely different irradiance values (see picture) on it.
I tried to adjust some radiance parameters, so increased -ad and decreased -lw but it did not help. Furthermore i tried to increase the -g parameter of Accelerad because in the simulation i get the warning:
rcontrib: warning - Stack overflow occured 20051 times in rcontrib
My current radiance settings are:
-ab 2 -ad 2048 -aa 0 -as 1024 -lw 2e-05 -dr 0 -g 8192
But so far nothing helped. Does someone maybe have a guess? I think it is about the radiance parameters but i am still really new to it and don’t completely understand the parameters.
Any help appreciated 
Hi @Yannick,
I’m not sure what your model looks like, but there might be a few things going on here.
The zero-value pixels probably correspond to the stack overflow errors you are receiving. No value is returned for a sensor that produces an error. Stack overflow errors in Accelerad are very rare. Could you have modeled your glazing as a double layer instead of a single layer, or positioned your model very far from the origin? If those don’t turn out to be the case, you could also try imposing a lower limit on -lr.
The high value pixels might be the result the -ad parameter. Depending on how you have modeled the sky and what size apertures the sky is visible through, you may need to set your -ad parameter much higher (and your -lw much lower).
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Hello @Nathaniel,
thanks a lot for your quick response and the detailed answer.
I got it fixed with setting -lr to 4, with which the stack overflow errors got resolved. Furthermore i increased -ad to 20000 and decreased -lw accordingly.
With these setting i got rid of the zero-pixels and high-value pixels. For anyone facing the same issue my radiance settings are the following:
-ab 2 -ad 20000 -lw 5e-05 -aa 0 - as 1024 -lr 4 -dr 0