Houdini 21.0 Nodes Copernicus nodes

Pyro Light Ambient Copernicus node

Builds a light field of ambient illumination of a VDB.

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Since 21.0

This operation constructs a light field that stores the intensity of light that reaches each voxel. The source of the light is the environment around a density VDB which then shadows the light.

Light operations can be chained together to accumulate multiple light sources and used as an input to the Rasterize Volume COP to render a VDB as lit smoke.

Parameters

Shading

Exposed Color

The color of light that is exposed to the ambient surroundings. This is normally white, but can be used to tint the effective environment map.

Occluded Color

The color of light where the voxel is not exposed to the ambient surroundings. Normally this is black, but setting this to white and the exposed color to a dark color will result in a self-lit look which works well for clouds.

Intensity

The linear brightness of the light.

Exposure

An exponential brightness of the light. Each 1 value higher is 2 times the brightness.

Density Scale

Scales the density VDB values, causing it to occlude light swifter.

Environment Map Offset

Angle to rotate the environment map around the Y-axis.

Quality

Steps Per MipMap

When tracing the occlusion rays, the MipMap level will be dropped each time this number of steps has been run. Having a low value here is useful as it makes the rays effectively thicker, so they become cones rather than rays.

Max Steps

The maximum number of samples that will be done while tracing an occlusion ray. Because higher MipMap levels have larger step sizes, the distance covered will be larger than just the voxelsize times the maxsteps.

Environment Map Resolution

Because only a few rays are used to sample the ambient light, the environment map must be downsampled to avoid aliasing. This is the resolution to resample it to.

MipMap Level

The starting MipMap level. When starting at a level 1, the light is computed in a half-res VDB and interpolated back to the full resolution, making the operation over eight times faster.

Inputs

density

A Float VDB storing the density to occlude light. This is also the topology used to build a light field. The light field will only be present where density was activated.

mipmap

An optional Float VDB MipMap from a Packed MipMap COP. If not provided, it will be computed internally.

light

An optional Vector VDB storing the amount of illumination at each voxel. The new light will be added to this, allowing lights to be chained.

envmap

An optional RGB layer storing the environment map in polar coordinates.

Outputs

light

The light that reaches each voxel from the ambient sources.

See also

Copernicus nodes