Date: Fri, 29 Mar 2024 02:08:43 +0000 (UTC) Message-ID: <64068546.233.1711678123244@ip-10-0-0-233.us-west-2.compute.internal> Subject: Exported From Confluence MIME-Version: 1.0 Content-Type: multipart/related; boundary="----=_Part_232_1181019645.1711678123242" ------=_Part_232_1181019645.1711678123242 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Content-Location: file:///C:/exported.html
Although a portal light is a rectangular shape, it is not interc= hangeable nor replaceable by a PxrRectLight because we get the illumination from the 3D environm= ent using a PxrDomeLight .
PxrPortalLight is one-sided. That is, there is no illumina= tion behind the portal. If we need to illuminate the back side, we can crea= te another portal facing the reverse direction.
We can add light filters to a portal light like any other lights. In fac= t, a PxrBarnLightFilter works great with this type of light.
For more information you can consult the technical paper:
Portal Lights do not work with the PxrEnvDayLight system. Use a PxrDomeL= ight with an appropriate HDRI or HDRI sequence.
All portal lights that are associated with the same parent dome li=
ght and the same portal name must have the same rotation
"Why do I use a portal light?"
Since lighting interiors with little or no direct lighting is difficult =
for a renderer to resolve, portal lights help direct the renderer's attenti=
on to the exterior source of light. RenderMan can make excellent use of the=
PxrPortalLight as shown below on the classic Classroom scene.
Both images are rendered with the same 32 samples per pixel. But you can pl=
ainly see how much more effective the result is with portal lights on the r=
ight than without on the left.
Intensity Multiplier
Intensity adjustment is relative to the parent dome light intensity. Thi= s gets multiplied by the parent dome light's intensity and power.
Color Tint
This parameter tints the color from the dome texture. Below each portal = has a different color assigned for a nice rainbow effect.
Map Gamma
Gamma-correct the texture. Each channel (RGB) can be a= djusted independently. If this map gamma is unchanged from its defaul= t, then it will inherit the map gamma from the parent dome light.
Enable Temperature
Turns color temperature on or off.
Color Temperature
The effect will be less pronounced on fully saturated monochromatic ligh= ts. Defaults to 6500K, which should be very close to white on most monitors= (D65 illuminant used by sRGB and Rec 709).
Primary Visibility
The light isn't directly visible to the camera by default. Turning this = on makes it visible and can be written to an LPE using the emission token, = 'O'
Specular Amount
Amount of specular light that is e= mitted. This is a non-physical control. You could use a light with Specular Amo= unt 0.0 to act purely = as a source of diffuse light for your scene objects and avoid adding highli= ghts. Note that the scene still collects indirect reflection off other obje= cts in the room.
Diffuse Amount
Amount of diffuse light that is em= itted. This is a non-physical control. You could use a light with Diffuse Amoun= t 0.0 to act purely as= a source of highlights for your scene objects.
All shadow parameters will be igno= red if the light's Trace Light Paths is enabled in Advanced. The below optio= ns are all non-physical controls when used out of their default state. If&n= bsp; Trace Light Paths is enabled then their physical nature is enforced.
Enable Shadows
Enable raytraced shadows. Below is= on (default) and off.
Shadow Color
The color of the shadows cast by e= mitted light. Below there are Red, Green, and Blue from different portal li= ghts.
.0 0.0 0.0
Shadow Max Distance
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 l= ight. You may use this control to artificially reduce the distance shadows = are cast. This may also increase render speed by not calculating shadows ou= tside this distance. Notice the shadows of chair and table legs as they are= cut off after a distance and the shadow on the wall at the front of the cl= assroom.
Shadow Falloff
The distance from the light at whi= ch 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 c= ut off by the Shadow Max Distance parameter. Below is an example with both paramet= ers being used and the falloff is increased. Note this parameter may impact= performance on complex lighting setups.
Shadow Falloff Gamma
The gamma of the shadow strength i=
n the falloff zone. This requires the use of Shadow Ma=
x Distance and
Trace Subset
Set of geometry to consider for traced shadow intersection. If this is n= ot specified, all geometry is considered for traced shadow intersection.
Don't Trace Subset
Set of geometry to ignore for traced shadow intersection. If this is not= specified, all geometry is used for traced shadow intersection.
Trace Light Paths
Enable light and photon tracing fr= om this light. This value enforces a physically-based light and as a side-e= ffect disables the above Shadows controls. Users may use this feature to selectiv= ely decide which lights emit photons when using the PxrVCM or PxrUnified In= tegrators.
Thin Shadow
Enable thin shadow and disable ref= raction caustics for this light. This parameter will be ignored if Trace Light Paths is enabled. This is a non-physical control that creates "fake" colored s= hadows for transmissive objects without needing to generate photons for cau= stics. Below we go from On (default) to Off (opaque shadowing). Notice we l= ose the colored shadows and interior colored reflection by choosing Off, bu= t we gain some rendering speed instead.
Visible in Refraction
Make a light visible through transmission effects like glass and windows= by turning this on.
Manifold Walk
Used with the PxrUnified Integrator and enabling Enable Man= ifold Walk to create inexpensive caustics. Note: You must dis= able Thin Shadows
Manifold Walk Exclude Group
Used with the PxrUnified Integrator and enabling Enable Man= ifold Walk, this trace set is ignored during manifold explora= tion to avoid stopping or shadowing manifold exploration rays
Light Samples
Specifies an override of the number of light samples to be taken for thi= s light source. If set to something other than zero, it will override the s= ampling performed by the integrator. You might find a need for this if you = have unsolvable noise from this light and need more samples.
Light Group
Specify the light group name used for light group LPEs. This is useful t= o generate per-light AOVs for later adjustment in compositing.
Importance Multiplier
Rather than setting explicit Light Samples, users can change the number = of samples the light will be assigned internally by changing this value. Re= nderMan creates a set of samples at render time for all lights in the scene= and changing this value rebalances the samples across the lights. Note tha= t increasing this value will cause more samples to be se= lected from this light while reducing it for others in the scene. Lower tha= n the default will decrease the samples while providing = more to others in the scene.
The bridge application such as RenderMan for Maya or Katana provides a c= onvenient interface to create and link a portal light to its parent dome li= ght. It also automatically assigns unique portal names for the portal light= s that do not have the same rotation as the parent dome lights. By default,= the portal light inherits all the parameters from its parent dome light. I= f a parameter is modified in the portal light, then the local overridden pa= rameter will be used instead. There are two exceptions: intensity = and color gets multiplied to the parent dome's intensity and= color.
The bridge product will emit all the modified parameters to the RIB for = PxrPortalLight. Note that PxrDomeLight is not being emitted.