Mastering Complex Light Sources for Accurate Optical Simulations with Ocean™

Introduction

Depending on the situation, you may have to use complex lighting conditions. In the context of an outdoor simulation, Ocean™ can use analytic polarized sky models, as well as high resolution, high dynamic range images, to light the scene, making it possible to simulate any outdoor weather conditions. But some light sources may need to be represented with geometries (surface, tube, sphere, …) with different degrees of complexity. Ocean™ is also able to simulate artificial lighting as well, by using emitting materials. For this purpose, Ocean™ includes a generic light source model, with three main parameters:

The base emission spectrum
The position modulation function, allowing to make the emittance depend on position in space. For instance, a grey-scale image may be used for modulating the object luminance.
A distribution function controlling the dependence of light intensity with direction in respect to the object’s surface.

This will enable modelling of complex light sources, such as spotlights, or sources described by tabulated data such as IES files.

Complex light sources

The following images were rendered in using various distribution functions for the light source. The performance is still the same and was not degraded by adding the emitter distributions.

IES light sources

IES is a standard format for describing light source distributions and is widely used for all kind of lighting devices from building to automotive. You can find Two IES emitter types in Ocean™: planar IES and sphere IES. They both work with type A, B and C IES files, which is quite unique.

Planar IES is suited for any kind of emitting surface, and will ensure that any elementary surface will emit according to a hemispherical distribution derived from IES data, and aligned with its normal. As the distribution rotates with the surface normal, it is more suited for planar light sources. It is mostly designed for lights with no or little backwards emission, such as car lights, ceiling integrated spots, and all area lights.
Spherical IES is suited for spherical emitting objects. It ensures that the full sphere emits according to a complete IES data. It is mostly designed for lights emitting in all directions, and not only in a hemisphere, such as candle lights, hang luminaries, non-focused bulbs, etc…

As IES data only provide light intensity values and no color or spectral information, it is up to the user to choose the light spectrum for the source. This spectrum is automatically scaled to preserve the IES light intensity.

IES light sources examples

Conclusion

To summarise, Ocean™ is a versatile solution for handling complex light sources in diverse simulations and visualizations. It can handle a wide range of conditions, from replicating outdoor environments with polarized sky models to simulating artificial lighting with emitting materials.
Ocean™’s generic light source model is equipped with parameters such as base emission spectrum and distribution function, which facilitates precise representation of intricate light sources. Examples demonstrate the software’s robust performance in rendering scenes with different distribution functions while maintaining quality even with complex emitter setups.

The integration of IES light sources, including planar and spherical options, expands Ocean™’s utility for various lighting devices. Its support for different IES file types enhances compatibility across applications, making it a valuable tool in architectural and automotive contexts.

In conclusion, Ocean™ is a sophisticated and capable tool for handling complex light sources, offering flexibility and precision that are crucial for accurate simulations. As the demand for realistic lighting in virtual environments increases, Ocean™ stands out as a valuable resource for professionals, ensuring accurate representation and immersive experiences in simulated worlds.

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