Accelerad / How to trigger it wih Honeybee for Image based simluation

Hello World,
I’m trying to find the best way to trigger Accelerad with Honeybee.

Is there any step by step guide on how to make honeybee work using it, in order to perform a radiation analysis?

I’d like to use this to calculate how much sun gets reflected by a curved facade. Radiance is taking hours, for a single shot. I have my hopes high with Accelerad, since I have 2 Nvida Quadro RTX that could help.

Any comment will be welcome

Best Regards

Hi @Carlos_BM,

Before you go too far down this path, have you looked at Roland Schregle’s photon mapping in Radiance?

Accelerad can probably get you something faster than Radiance, depending on the details of your model and settings, but it won’t get you anything more accurate because it uses the same algorithms. Photon mapping will be both faster and more accurate for reflection from curved facades.


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Thanks, Nathaniel, I’m looking for a tool that could handle inputting a complex geometry facade and get an understanding of its reflections and the radiation levels, in a tolerable time frame. I used for some time a software called Iray+ with 3Ds max to get LUX levels (as it can handle any geometry no matter how big or complex, and give us results in a matter of minutes, as false colour render) but now I need to jump into the radiation quantification, and radiance struggles to return results if geometries are complex and big. For you to have an idea I need to insert the facade of building like this And get the results of its reflections around, in the adjacent facades and street level. If you have any idea of other software (paid), no radiance based, I will appreciate it. Thanks!!

Hi @Carlos_BM,

The answer will depend on how you are modeling this. Are you modeling specular glazing or mirror surfaces? If Radiance is taking a long time for the building in the rendering you linked, then I suspect you are using parameters that are inappropriate for radiation simulation. Perhaps you have set a very high -ab or -lr, which you would do for visible lighting but which is unnecessary for solar radiation. Have you tried an -ab 0 simulation to get just the direct solar and direct-direct reflection components?

Remember that the simulation time in Radiance is proportional to the number of rays and has only minimal dependence on the size of the model. If you want to make Radiance faster, avoid sampling unnecessary rays that don’t contribute much to the total radiation you’re measuring.

It should of course be possible to do radiation quantification with Iray as well, as it also claims to be able to simulate caustics. You just need to set your light source in radiation units rather than visible light units. However, you will need to do some research on how Iray calculates caustics, whether there are extension needed for caustics calculation, etc. I am not an expert on Iray.

My overall recommendation, though, would be to use Radiance’s photon mapping. This will give you the benefit of much more extensive validation than Iray has, and photon mapping is purpose-built for the problem you describe.

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Hi Nathaniel thanks a lot for your comments.
will check out Photon Map for blender.