Houdini 22.0 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

Note

Although COP Pyro is in COPs, you need DOP level permissions to use it. This means that COP Pyro is not available in Houdini Core, but only in Houdini FX, Houdini Apprentice, Houdini Indie, and Houdini Education.

This node 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.

Multiple light operations can be chained together to accumulate light from multiple sources. The resulting light field can be used as an input to the Rasterize Volume COP node 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 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

Controls the linear brightness of the light.

Exposure

Controls the exponential brightness of the light. Each increase of 1 doubles the brightness.

Density Scale

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

Environment Map Offset

Controls the angle used to rotate the environment map around the Y-axis

Quality

Steps Per MipMap

Controls how many tracing steps are performed before dropping to the next MipMap level when tracing occlusion rays. Lower values make the rays effectively thicker, causing them to become more like cones than rays.

Max Steps

Controls the maximum number of samples taken while tracing an occlusion ray. Since 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 parameter controls the resolution to which it is resampled.

MipMap Level

Controls the starting mipmap level. Starting at MipMap level 1 computes the light in a half-resolution VDB and interpolates the result back to full resolution, making the operation more than 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