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Number of Emitted Photons

The number of photons emitted from the light controls specifies the number of photons in the Photon Map. Photons can be emitted until either a specifed number has been stored or until a maximum number was emitted.

The default value of is 10 000 which renders in a reasonable amount of time. Low numbers of emitted photons are calculated in faster render times but create blurry effects. Very low values in this case 100 can be used to show a quick estimate of where photons are stored in the scene.

High numbers of photons emitted from the light source increase the precision of the caustic effect. Good quality caustic effects require values of at least 100 000 and the numbers can range up tp 1 000 000.

This value is proportional to the time taken for calculation at rendering and so the highest values will take a longer and are generally only used for final renderings.

The graininess which can be seen opposite can be reduced by increasing the accuracy not by changing the number of the photons.

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Number of Emitted Photons
Further Information
Susan Windeatt