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The Fire Lights rollout controls how the fire casts light on the other scene objects as well as on the Phoenix FD Simulator's own Smoke.
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When using Global Illumination (GI), the fire will illuminate everything (scene objects as well as the Simulator's own Smoke) automatically but the rendering will take longer. Turning on Create Fire Lights simulates GI by placing light sources in the bright parts of the fire, which gives similar results and renders much faster. The color and power of these lights are adjusted automatically but can be overridden. The smoke illumination caused by the Simulator's own fire can be controlled with the Self Shadowing option. If enabled, the smoke will obstruct the path of light from the fire, creating a much more realistic look but decreasing rendering performance. To gain back the rendering speed, set Self Shadowing to Grid-based and |
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decrease the Light Grid Resolution (%) parameter to reduce the |
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number of generated lights. |
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All Fire Lights options are ignored when rendering with V-Ray GPU. Enable Global Illumination from the V-Ray Settings if you need the Smoke and/or the scene to be illuminated by the fire. |
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UI Path: ||Select PhoenixFDSim|| > Attribute Editor > Rendering rollout > Fire Lights rollout |
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If Create Fire Lights is enabled when rendering using GI, additional light sources will still be created by the fire at render time. You should disable Emit LightCreate Fire Lights if you want to let the GI naturally illuminate the scene. Using Generate GI and Receive GI options from the V-Ray Object Properties will be ignored while Create Fire Lights is enabled. |
Light Power on Scene | emLightsPowerMult – Controls the light intensity on all scene objects except the Phoenix FD Simulator itself.Anchor PowerMult PowerMult
Light Power on Self | emLightsPowerOnSelfMult – – Controls the power of the light on intensity over the Simulatorsimulator's own smoke. This will not change the intensity and color of the fire - itself; only the illumination produced on over the smoke is affected.
Light Power on Scene | emLightsPowerMult – Controls the light intensity over all scene objects except the Phoenix FD Simulator itself.
Self Shadowing | emLightsSelfShadow – Enables self-shadowing of the smoke from the fire's light. If enabled, the smoke will obstruct the path of light from the fire, creating a much more realistic look but decreasing rendering performance. To gain back the rendering speed, set Self-Shadowing to Grid-based and use decrease the Light Grid Light Grid Resolution (%) parameter to reduce the resolution of the light gridnumber of generated lights. See the Self-Shadowing example.Anchor SelfShadowing SelfShadowing
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Light Grid Resolution (%) | emLightsGrid – Specifies the resolution of the light grid as a percentage of the fire grid's resolution. Perfect illumination from fire could be achieved by placing a light in each fire cell, but this could take a tremendous amount of time to render and such accuracy is usually not necessarynecessary to approximate the fire's illumination convincingly. In order to speed up rendering, a separate light grid is created internally which can have a lower resolution than the fire grid, and this light grid is populated with one sphere Omni light per each cell. The lower resolution (and thus fewer lights) speeds up rendering at the expense of some illumination detail, which might not always be visible anyway. At a value of 100, the light grid has the same resolution as the fire grid. The smaller the Light Resolution is, the smoother the illumination will become becomes and the faster the rendering will beis. However, at very low values the fire might not blend well with the light it casts on the smoke. See the Grid Reduction example.
Light Cut-off | emLightsCutoff – This is a V-Ray specific control that works the same as the VRayLight cutoff parameter. This parameter specifies a threshold for the light intensity, below which the light will not be computed. This can be useful to limit the effect of the Phoenix light to some distance around the simulator. Larger values cut away more light; lower values make the light range larger. At 0.0, the light will be calculated for all surfaces, but the rendering could slow down significantly.
Decay Type | emLightsDecayType – Controls how quickly the simulator's emissive light fades when travelling away from the fire light sources:
None – The light does not fade at all unless obstructed
Inverse – The light intensity fades with the inverse of the distance. E.g. at a distance of 5 units, the intensity will be 1/5th of the intensity of the emitter.
Inverse Square – The light fades with the inverse square of the traveled distance. This is physically correct light propagation. For example, at a distance of 5 units, the intensity will be 1/25th of the intensity of the emitter.
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The parameters below control how many rays have to be traced in order to calculate the lighting. The larger the ray count, the better looking the result will be, but it will render more slowly. For general explanation of how light sampling works, see the V-Ray Image Sampler page. |
Direct Subdivs | emLightsSubdivs – Specifies – Sampling control for direct lighting. This parameter controls the number of subdivisions to be used with V-Ray DMC Sampling. Higher values will increase the quality but will slow down the renderthe rays traced from the shaded point toward the fire in order to find the optical passability between them. The number of rays cast towards the fire is the square of this value. If the value is zero, a special case is used and all emissive lights are sampled. This could be quite slow when having a big number of emissive lights.
Caustic Subdivs | emLightsCaustSubdivs – Sampling control for Caustic effects. Similar to GI subdivisions, but used when caustics are calculated.
Create Lights Even If Not Renderable | emLightsPersist – When – When enabled, forces the Simulator simulator to emit light over the scene even if rendering the rendering simulator itself is disabled. Can be used for compositing when the fire simulator is rendered in a separate pass.
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