111 lines
3.9 KiB
ReStructuredText
111 lines
3.9 KiB
ReStructuredText
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******************
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Irradiance Volumes
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******************
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Diffuse indirect lighting is stored in volumetric arrays.
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These arrays are defined by the user using Irradiance Volume objects.
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They control how arrays are placed in the world as well as their resolution.
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Lighting is computed at the dot positions visible when the Irradiance Volume object is selected.
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.. seealso::
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:doc:`Indirect Lighting </render/eevee/render_settings/indirect_lighting>`.
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If Ambient Occlusion is enabled, it will be applied onto diffuse indirect lighting.
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If both Ambient Occlusion and "Bent Normals" are enabled
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the indirect lighting will be sampled from the least occluded direction and appear more correct.
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.. reference::
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:Panel: :menuselection:`Object Data --> Probe`
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Distance
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A probe object only influences the lighting of nearby surfaces.
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This influence zone is defined by the Distance parameter and object scaling.
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The influence distance varies a bit, depending on the probe type.
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For Irradiance Volumes, the influence inside the volume is always 100%.
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The influence decays only outside of the volume until
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the distance to the volume reaches the Distance parameter value (in local space).
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Falloff
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Percentage of the influence distance during which the influence of a probe fades linearly.
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Intensity
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Intensity factor of the recorded lighting.
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Making this parameter anything other than 1.0 is not physically correct. Use it for tweaking or artistic purposes.
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Resolution
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Spatial resolution for Irradiance Volumes is determined per probe.
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The local volume is divided into a regular grid of the specified dimensions.
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One irradiance sample will be computed for each cell in this grid.
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Clipping
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Defines the near and far clip distances when capturing the scene.
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.. warning::
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Clipping distances are applied at the samples positions and *not* at the grid origin.
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Visibility Collection
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In some cases, it is useful to limit which objects appear in the light probe's captured lighting.
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For instance, an object that is too close to a capture point might be better excluded.
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This is what the visibility collection does.
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Only objects that are in this collection will be visible when this probes captures the scene.
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There is also an option to invert this behavior and effectively hide the objects in this collection.
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.. note::
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This is only a filtering option. That means that if an object is not visible at render time
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it won't be visible during the probe render.
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Visibility
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==========
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For every grid point a small Variance Shadow Map is rendered.
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This visibility cubemap is used to reduce light leaking behind occluders.
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You can tweak the size of this map inside the render settings and
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tweak the bias and blur factors per grid inside the Probe Properties tab.
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Bias
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Reduces self-shadowing.
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Bleed Bias
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Increases the "contrast" of the depth test result.
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Blur
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Amount of blur to apply when filtering the visibility shadow map.
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Does not increase runtime cost but has a small effect on baking time.
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Blending
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========
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The lighting values from an Irradiance Volume will fade outwards until the volume bounds are reached.
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They will fade into the world's lighting or another Irradiance Volume's lighting.
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If multiple Irradiance Volumes overlap, smaller (in volume) ones will always have more priority.
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If an object is not inside any Irradiance Volume, or if the indirect lighting has not been baked,
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the world's diffuse lighting will be used to shade it.
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.. tip::
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- When lighting indoor environments, try to align grids with the room shape.
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- Try not to put too much resolution in empty areas or areas with a low amount of lighting variation.
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- You can fix bad samples by adding a smaller grid near the problematic area.
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Viewport Display
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================
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Influence
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Show the influence bounds in the 3D Viewport. The inner sphere is where the falloff starts.
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Clipping
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Show the clipping distance in the 3D Viewport.
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