Render: Physically Accurate Dispersion

Computer generated images have become indistinguishable from real world images. Modern rendering applications, like finalRender, use the power of GPU and CPU rendering to recreate reality in all of its beauty. The technology behind all of this is called trueHybrid™, it is the manifestation of an artists dream by leveraging all of the power offered by the CPU and GPU.

Physically Based Spectral Wavelength Rendering

finalRender treats colors totally different from what you might know of other rendering applications on the market. Colors in finalRender are treated as a combination of individual wavelengths, just like in the real world. An overlay of multiple frequencies of light results in the final colors we all see around us. Lets take a rainbow for example, water drops disperse (or split) the sun light into its individual components and this Dispersion of light presents to us this awe inspiring rainbow of colors - right there in the sky!

I took dew (water droplets) as an example of why such effects, even when they are subtle, are so important in creating photo real images. A Dispersion effect (a wavelength-dependent refractive index), inside of the water drops, causes different colors to refract at different angles, splitting white light into a spectrum.

Here is my 3D scene fully rendered in 3ds Max and finalRender.

Have a close look, the No-Dispersion image shows flat un-sparkly water drops. The drops are missing the life and brilliance you would expect from Dispersive media. Water drops are like little diamonds, they sparkle and shine! Lucky for me, Dispersion is a simple one parameter control in finalRender which allows me to turn it on and off to do multiple renderings of the same situation. Being a physically accurate spectral renderer, finalRender is able to recreate the real world Dispersion effect without any extreme calculation overhead - thanks to trueHybrid™ and the added power of NVIDIA GPUs.

Find below a HD Image without any Dispersion effects turned on.

And here is the same image but with dispersion added to the water droplets.

Even though it is a subtle effect, it is essential to the final quality and realism of the image. Physically Based Spectral Wavelength Rendering is the only accurate and correct method to re-create optical effects like Dispersion, Diffraction or Interference including radiation based color effects (black body radiation).

Do you Remember ? Some years ago Dispersion was a Hype in the rendering market!

I'm long enough in this industry, I started some 20 years ago and I remember all the hypes we went through, while offering our ground breaking rendering application finalRender Stage-0 to 3ds Max users. At some point one renderer manufacturer came up with the idea to add Dispersion (they are no longer in business) to their rendering solution. What an outcry it was ! Suddenly everyone wanted to have Dispersion in their renderers - so all of the developers got to work and added that feature. Funny fact: No one ever used it from then on! Besides the marketing material each developer created - no one ever used Dispersion in their renderings. You might ask why ? It was ~20 years ago and rendering of such effects, even with brutal tricks, took ages and was not practicable at all. Also do not forget all those renderers offering Dispersion effects back then (and today) were based on a simple RGB color model and this color model is just dead wrong and has nothing to do with the real world effect of Dispersion.