Modelling Water with Radiance

Hello there,

I am doing some Glare analysis for which it would be fundamental to model water properly.

I am having difficulties to input the materials definitions I have found in this Link in the honeybee library, I think I am formatting the string not properly,

Any suggestion?


Hi Amedeo,

You can do it as simple as adding the materials to the library and apply them to surfaces. Just make sure to create the file and copy it inside c:\radiance\lib. Here is the results:

Check this Hydra for one of the approaches mentioned in the link: (…;)


Thanks A lot Mostapha!

Hi Mostapha,

Thank you for this post, We all proud of you.

For one educational project, I am trying to evaluate the effect of thick water wall on daylight distribution inside a room. (as you know it is not possible with glass material)

this water wall is oriented to the south with thickness about 25 cm.

I have defined a dielectric material in radiance for Water as this:

void dielectric Water



5 0.8695 0.8695 0.8695 1.33 0

#red_transmissivity green_transmissivity blue_transmissivity index_of_refraction 0

Therefore, I defined 2 surfaces for front and back and since there is just one layer of dielectric, I don’t need using any interface material. But the direction of these surface is very tricky. both directions have to be toward outside (?)

should I rotate them inside in reverse ray tracing??? The resultant values are significantly different.

any comments would be really helpful for me.
thanks in advance.

Hi Mostapha,
I am trying to make some illuminance analyses, my building is very near to river, so i think that it would be good to consider reflectance of water. I have found this example but,I could not find the `‘’ file to copy it to rad. library.

The link that you gave in 2015 is not available.
I found sth like this ( but also I dont know how to create a .cal file.

Paste the below formatted text into Notepad (or any other text editor) and save it as in the lib folder of your Radiance installation (Most likely C:\Radiance\lib if you are on Windows). lib folder is the one that RAYPATH variable points to in your Windows environment.

	Ripples for water, whatever


	A1 = degreee of waviness
wave_x = wave_mag * noise3a(Px, Py, Pz);
wave_y = wave_mag * noise3b(Px, Py, Pz);
wave_z = wave_mag * noise3c(Px, Py, Pz);

wave_mag = min(A1, .5*Rdot);

Regarding this…

I am not sure if using specifically would be useful. As you from the definition for, it is generated with a noise function and thereby has an element of randomness to it. That randomness looks realistic in rendered images but might create issues with illuminance-based calculations as the wave pattern might create random distortions in your results. It is also likely to be impossible to keep your results repeatable as the wave patterns are likely to change every time you run a new simulation, even for the same model.

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