LuxCoreRender Forums

I need irradiance for the BiDir engine.

B.Y.O.B. wrote: Fri Aug 24, 2018 10:32 pm If you use Blender and the new BlendLuxCore addon, you can just enable the contour lines plugin in the imagepipeline settings and start the render (it even works in viewport render).... it is a bit hard to find the right values for the different parameters of the contour lines.

The contour lines plugin works very fine, but I don't find suitable parameters for my scene. I guess the reason is my use of the BiDir render engine that I need for the tracking of the laser beams light path. The BiDir engine does only support a few AOV's and not the irradiance.

However, I found a bypass calculating the brightness of the rgb colour using the following compositor nodes:
The result is quite good: So, the colouring works, but the render result (.png) is not so sensitive to give me precise brightness.
I think the result would be very precise, when I could work with the basic irradiance.

Is there any way, to get the irradiance for the BiDir engine?

Burk wrote: Tue Aug 28, 2018 8:27 pm So, the colouring works, but the render result (.png) is not so sensitive to give me precise brightness.
I think the result would be very precise, when I could work with the basic irradiance.

You should work in some HDR format (like .exr) both as input and output but I have no idea if it is supported by Blender.

Burk wrote: Tue Aug 28, 2018 8:27 pm Is there any way, to get the irradiance for the BiDir engine?[/b]

Not at the moment.

Dade wrote: Tue Aug 28, 2018 8:45 pm You should work in some HDR format (like .exr) both as input and output but I have no idea if it is supported by Blender.

All passes of the render result in Blender have HDR.
You should set the output format to EXR instead of PNG to get the HDR result.

However, the color ramp node probably does not output HDR.

You can use the file output node in the compositor to save multiple composited images in one go as different files:
https://docs.blender.org/manual/en/dev/ ... /file.html

Dade wrote: Tue Aug 28, 2018 8:45 pm You should work in some HDR format (like .exr)

Yes, thanks that works.

B.Y.O.B. wrote: Tue Aug 28, 2018 8:51 pm However, the color ramp node probably does not output HDR.

Thanks, the problem with the color ramp was only the overexposure, so I had to adjust the shutter time of the camera.

The result looks fine for me:

Burk wrote: Wed Aug 29, 2018 11:54 am Thanks, the problem with the color ramp was only the overexposure, so I had to adjust the shutter time of the camera.

That's the input side, I think it only accepts values in the 0..1 range and clamps everything outside that range.
So you have to scale the HDR input until the range you want to map lies in the 0..1 range (which you did through tonemapping).

Hi,

Regarding the mentioned automation: it was just a quick idea of mine so it might work, but I guess it will cause a lit of troubles until you've reached your target...

The idea was using the interface and the API of a CAD system to write a script that is basically your own little ray trace.

Your input are the media interface surfaces, your starting point and a direction. Also some IOR will be necessary. From this input it might be possible to use CAD capabilities to find intersections, measure incidence angle and calculate result beams and their intensities.
Usually some annotations could be created and positioned within scripting as well.
Ok first step done. Your should have a bunch of lines and some intensities now. To create some kind of geometry use CAD API to sweep some little tubes around the lines and create a mesh that could be used for lux...

Additionally there might be an option or a workaround to create 3d geometry from the annotations.

Now with luxcore API you can grab this meshes and turn each of this tubes into light sources with an emittance fitting to your calculated intensity or your desired colour.

Writing that down makes me thinking that this approach is too complicated... sorry.

BR

lighting_freak wrote: Wed Aug 29, 2018 6:11 pm Writing that down makes me thinking that this approach is too complicated... sorry.

Yes, I think too, that is to complicated. At least for my capabilities and capacities.
But no problem, nice idea, thanks.
Fortunately the guys behind lux have done the most of that coding (calculating the angles, light power etc.), so that I've found a solution for me on that basis.

Something I stumbled upon: https://github.com/qatnonoil/Alhazen
Might be useful for you, or it might not, no idea. But the second image in the readme looks like the stuff you posted.