Houdini 18.0 Nodes VOP nodes

pxrdistantlight VOP node

Parameters

intensity: intensity: Specify the intensity of the light source linearly. The light intensity is computed using physical units. The default light begins at a high value of 50000.0.

exposure: exposure: Specify the intensity of the light source as a power of 2 (in stops). Increasing the exposure by 1 will double the energy emitted by the light source. A value of 0 produces an intensity of 1, -1 produces .5. Real world lighting has high energies and typical exposures are low values while you may have to type a really large number for equivalent Intensity. This is also comfortable to artists familiar with photographic measurements.

angleExtent: angleExtent: Opening angle of the light source in degrees (Sun=0.53). Higher values soften the shadow edges (light rays become less parallel) while lower values make it sharper. Note that increasing this parameter also increases the amount of light in the scene and you may need to significantly reduce the light intensity/exposure to compensate or you may use Area Normalize to prevent changes in illumination.

lightColor: lightColor: The color of the emitted light.

enableTemperature: enableTemperature: Turns the color temperature on or off.

temperature: temperature: Allow the user to choose the color temperature of the light in Kelvins. This control will act like a filter (a tinted transparent surface) in front of your light. If your light is white, you will get the chosen color temperature. If your light is colored, the color temperature will make it cooler (over 6500K) or warmer (below 6500K). NOTE: The effect will be less pronounced on fully saturated mono-chromatic lights. Defaults to 6500 K, the D65 illuminant (white point) used by sRGB and Rec. 709.

emissionFocus: emissionFocus: Off-axis cosine power exponent to shape the emission. This controls the spread of the light. Higher number will start focusing the light towards the center and thus narrowing the light spread. For the PxrDistantLight it will appear to dim the lighting as you increase the parameter. To alter the shadowing to appear larger/softer you should use Angle Extent.

emissionFocusTint: emissionFocusTint: Off-axis light color tint. This tints the emission in the falloff region starting from the off-angle direction of the light towards the center. By default, the tint color is black (none). In addition to tinting, value greater than white will also increase the intensity of the falloff region. For the PxrDistantLight this will tint the color of the light. Higher Emission Focus settings will increase the saturation of the chosen color.

specular: specular: Amount of specular light that is emitted. This is a non-physical control. You could use a light with Specular Amount 0.0 to act purely as a source of diffuse light for your scene objects and avoid adding highlights.

diffuse: diffuse: Amount of diffuse light that is emitted. This is a non-physical control. You could use a light with Diffuse Amount 0.0 to act purely as a source of highlights for your scene objects.

enableShadows: enableShadows: Enable raytraced shadows.

shadowColor: shadowColor: The color of the shadows cast by emitted light.

shadowDistance: shadowDistance: The maximum distance of the shadow starting from the position of the point being shaded. -1.0 is unset which will use the distance between the point being shaded and the point on the light. You may use this control to artificially reduce the distance shadows are cast. This may also increase render speed by not calculating shadows outside this distance.

shadowFalloff: shadowFalloff: the distance from the light at which shadow falloff begins. -1.0 turns off shadow falloff. This is used along with Shadow Max Distance to create a false fade for shadows that are reduced or cut off by the Shadow Max Distance parameter

shadowFalloffGamma: shadowFalloffGamma: The gamma of the shadow strength in the falloff zone. This requires the use of Shadow Max Distance and Shadow Falloff.

shadowSubset: shadowSubset: Set of geometry to consider for traced shadow intersection. If this is not specified, all geometry are considered for traced shadow intersection.

shadowExcludeSubset: shadowExcludeSubset: Set of geometry to ignore for traced shadow intersection. If this is not specified, all geometry is used for traced shadow intersection.

areaNormalize: When normalize is enabled, the amount of light contributed to the scene will not change as you change the angleExtent of the light source. This makes it easier to adjust highlight size without changing scene lighting.

traceLightPaths: traceLightPaths: Enable light and photon tracing from this light. This value enforces a physically-based light and as a side-effect disables the above Shadows controls. Users may use this feature to selectively decide which lights emit photons when using the PxrVCM or PxrUPBP Integrators.

thinShadow: thinShadow: Enable thin shadow and disable refraction caustics for this light. This parameter will ignored if Trace Light Paths is enabled. This is a non-physical control that creates 'fake' colored shadows for transmissive objects without needing to generate photons for caustics.

fixedSampleCount: fixedSampleCount: Specifies an override of the number of light samples to be taken for this light source. If set to something other than zero, it will override the sampling performed by the integrator. You might find need for this if you have unsolvable noise from this light and need more samples.

lightGroup: lightGroup: Specify the light group name used for light group LPEs. This is useful to generate per-light AOVs for later adjustment in compositing.

importanceMultiplier: Importance of this light for noise control.

VOP nodes