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How does photon mapping work?
With photon mapping, light packets called photons are sent out into the scene from the light sources. Whenever a photon intersects with a surface, the intersection point and incoming direction are stored in a cache called the photon map.
Is global illumination the same as ray tracing?
“Global illumination,” the more advanced form of ray tracing, adds to the local model by reflecting light from surrounding surfaces to the object. A global illumination model is more comprehensive, more physically correct, and it produces more realistic images.
What is mass of photon?
According to electromagnetic theory, the rest mass of photon in free space is zero and also photon has non-zero rest mass, as well as wavelength-dependent. The very recent experiment revealed its non-zero value as 10 – 54 kg ( 5.610 × 10 – 25 MeV c – 2 ) .
What is VFX GI?
Global illumination (GI), or indirect illumination, is a group of algorithms used in 3D computer graphics that are meant to add more realistic lighting to 3D scenes.
Has a photon got mass?
Light is composed of photons, so we could ask if the photon has mass. The answer is then definitely “no”: the photon is a massless particle. According to theory it has energy and momentum but no mass, and this is confirmed by experiment to within strict limits.
When do you need to use photon mapping?
Photon mapping is used to calculate the effects of indirect lighting and caustics. Too many photons would be needed in the photon map to accurately handle specular/glossy surfaces and direct lighting. Approximating the Rendering Equation
How is the number of photons at each light determined?
Finding the number of photons to create at each light depends largely on whether decent radiance estimates can be made during the rendering pass. For good radiance estimates the local density of the photons at surfaces need to provide a good statistic of the illumination. Figure recreated from [1]
How is the illumination solution represented in a photon map?
Photon mapping decouples the illumination solution from the geometry and the solution is represented in a spatial data structure called the photon map. This decoupling proves to be quite powerful as the rendering equation’s terms can be calculated separately and stored into separate photon maps.
How is the photon map used in caustics?
Visualizing the photon map directly basically means we gather N nearest photons and estimate the radiance directly from that information using the last equation from the previous section. During the photon tracing phase a separate photon map is used for caustics.