Lighting compositing node

Adds a light to the image.

All

Parameters

Local variables

See also: Bump, Depth of Field, Emboss, Fog

This operator adds a light to the image. The light can be directional or non, and have ambient, specular and diffuse components. The image can be a flat image, an image with a bump map, or a deep raster image containing point and/or normal planes.

Flat Lighting

Flat lighting requires no extra information. It assumes the image is a flat plane, and applies the lighting equation to the pixels. The image occupies the area (0,0,0) to (1,1,0).

The light position should have a positive Z value. The center of the image is (0.5, 0.5, 0). The distance the light is from Z=0 determines the brightness and the light’s shape (if a cone line is used).

Bump Map Lighting

Bump Map lighting requires a bump map, which can be produced with the Bump COP. This type of lighting is similar to Flat lighting, except that the surface normals are perturbed based on the bump map.

To adjust the height of the bumps, you will need to brighten or dim the bump map with a Bright COP. Or, if the bump map was created with the Bump COP, adjust the Bump Height parameter there.

Deep Raster (3D) Lighting

3D lighting can be done with the help of Point and Normal maps, which can be generated from the Deep Raster tab of the Mantra ROP. If only a Point map is present, the Lighting COP will attempt to build normals from the point positions. If only a Normal map is present, the process is similar to that of Bump Map lighting, and the points are assumed to be in the range (0,0,0) to (1,1,0).

The light can be placed anywhere relative to the 3D points. It is useful to use the viewport inspect function (((i))) to determine the 3D point values so the light can be positioned more accurately.

Volumetric Lighting

Volumetric lighting can be used with any of the above lighting techniques, though it is most effective when used with 3D lighting. Volumetric lighting adds an atmospheric light-scattering effect so that the cone of light can be seen.

Since volumetric lighting is quite time consuming to compute, it is a good idea to get all your other lighting parameters setup first, and then enable this option.

If the alpha plane is scoped, the amount of light at each point is placed in it.

Overloading VEX Parameters

This operator is implemented in VEX, which supports parameter overloading. If the first input has a plane which matches an operation parameter’s channel name, the input plane will be used as the parameter’s value, effectively overriding it. The overloaded parameter is then evaluated from the plane on a per-pixel basis.

eg. If the input COP has the following planes:

C{r,g,b}
A
fogdens

and it is fed into a VEX Fog COP, the fog density will be determined at each pixel by the fogdens plane, since the Fog Density parameter’s channel name matches the 'fogdens' channel name.

Scoping

This operation may be restricted to certain planes, or components of planes. In addition, the operation may be applied to a subset of frames within the sequence. An image must have both its frame and plane scoped to be modified.

Images that are not modified are passed through, which does not take any memory or processing time.

Masking

This operation may be masked, which restricts the operation to an area of the image. The mask may be inverted, brightened or dimmed.

The mask input is on the side of the node. The label on the connector indicates the plane being used as a mask.

The mask input can also be scaled to fit the output image’s resolution, if they differ. However, if this node changes more often than the mask input, it is faster to place a Scale COP in front of the mask input to do the resize, as the resize will not occur on every cook of this node.

Parameters

Lighting

Surface Type

Specifies the type of surface lighting to use:

Flat	Image has uniform normals and uniform depth.
Bump Map	Image has bumped normals and uniform depth.
Point & Normal	Image has normal & point maps for 3D lighting.
Point Only	Image has a point map for pseudo-3D lighting.
Normal Map	Image has uniform depth and varying normals.

Eye Distance

The distance from the eye to the image (at Z=0).

Ambient

The ambient component of the light.

Diffuse

The diffuse component of the light.

Specular

The specular component of the light.

Correct for Aspect Ratio

If the image is not square, this adjusts the coordinates so that spotlights are still circular.

Color Operation

How to apply the light to the existing image:

Light Existing Color	The image color is used as the color of the surface, and the lighting calculation replaces it.
Add to Existing Color	The image color is used as the color of the surface, and the lighting calculation is added to it.
New Lighting Only	The image color is ignored, and replaced by the new lighting. This will show only the ambient, diffuse and specular colors.

Material

This tab allows you to change the diffuse and specular models.

Diffuse Model

The type of diffuse model to use:

Simple	Simple dot product model.
Oren-Nayar	Rougher material model, like clay.

Diffuse Roughness

The roughness for the Oren-Nayar model.

Specular Model

The specular model to use, Phong or Blinn.

Exponent

The Phong specular exponent.

Roughness

The Blinn roughness parameter.

Light

Light position and orientation.

Position	The position of the light. In Flat, Bump Map and Normal Map modes, the image coordinates are {0,0,0} (bottom left) to {1,1,0} (top right).
Attenuation	The distance at which the light is at 50% intensity.
Directional Light	If on, the light is directional.
Direction	The direction vector of the light.
Cone	The cone size of the light, in degrees.
Cone Falloff	The falloff cone size of the light, in degrees.
Falloff	The falloff function for the light.

Volumetric

Adds volumetric light effects. Takes quite a bit longer to compute.

Atmosphere Scatter	The amount of light scatter the atmosphere causes. Higher numbers produce foggier lights.
Light Falloff	The distance that the volumetric fog extends away from the light.
Falloff Function	The volumetric fog falloff function.
Light Core Size	Increases or decreases the light hotspot size.
Ray March Step	The step size when marching through the light volume. Smaller values produce finer results at the expense of computation time.

Planes

Bump, Point Normal Planes in 2nd input	If on, all the specified planes are in input 2, otherwise they are in input 1.
Bump, Point, Normal Name	The name of the corresponding input planes.

Mask

A mask can be chosen to limit the effect of the operator to areas defined by the mask. The mask can be taken from the mask input (side input) or from the first input itself.

Effect Amount

If no mask is present, this blends the output with the input by a constant amount (0 = all input, 1 = all output).

If a mask is present, this amount multiplies the mask.

Operation Mask

Selects the mask plane to use as a mask from the mask input. The mask can be selected from:

A mask can be a component of a plane or an entire plane. If a vector plane is supplied as a mask, its components are multiplied by the images' components.

Scalar Mask ('A', 'C.r')

C.r = I.r * M
C.g = I.g * M
C.b = I.b * M

Vector Mask ('C')

C.r = I.r * M.r
C.g = I.g * M.g
C.b = I.b * M.b

First Input	Useful for masking the operation to the image’s own alpha plane.
Mask Input	Selects the mask from the side mask input.
Off	Turns off masking, without requiring disconnection of the mask input (useful for temporarily disabling the mask).

Resize Mask to Fit Image

If the mask image is a different resolution than the output image, turning on this parameter will scale the mask to the output image’s resolution.

If this node is changing constantly, and the mask is not, it is somewhat faster to put a Scale COP down to do the resize for the mask image. Otherwise, the scale will occur every time this node cooks.

Invert Mask

Inverts the mask so that all fully 'masked' portions become unmasked. This saves you from inserting an Invert COP after the node with the mask.

Scope

Plane Scope

Specifies the scope for both the RGB components of Color, Alpha, and other planes. The (C)RGBA mask only affects Color components and Alpha. 'C' will toggle all the RGB components.

For planes other than Color and Alpha, the plane name (plus component, if applicable) should be specified in the string field. The pulldown menu can be used to select planes or components present in this node.

A plane is specified by its name. A component is specified by both its plane and component name. The '*' wildcard may be used to scope all extra planes. Any number of planes or components can be specified, separated by spaces.

Examples:

P
N.x N.y
P N Pz

Frame Scope

Allows scoping of specific frames in the frame range. This is in addition to the plane scope (so a plane at a certain frame must be both plane scoped and frame scoped to be modified).

All Frames	All frames are scoped.
Inside Range	All frames inside a subrange are scoped.
Outside Range	All frames outside a subrange are scoped.
Even Frames	Even numbered frames are scoped.
Odd Frames	Odd numbered frames are scoped.
Specific Frames	A user-defined list of frames are scoped.

Frame Range

For Inside/Outside range, this parameter specifies the subrange of the sequence to scope (or unscope). This can be edited in Timeline viewer mode ( Ctrl + 2 in viewer).

Frame Dropoff

For Inside/Outside Range, this parameter specifies certain number of frames before and after to slowly ramp up to scoped. The operation will be blended with its input to 'ease in' or 'ease out' the scoping effect over a number of frames. This can be edited in Timeline viewer mode ( Ctrl + 2 in viewer).

Non-scoped Effect

For unscoped frames, this sets the blend factor between the input and modified images. Normally this is zero (use the input image). By setting this to a non-zero value, you can make unscoped frames be 'slightly' unscoped. The value can vary between 0 (unscoped) and 1 (scoped).

Frame List

The frame list for 'Specific Frames'. Frame numbers should be separated by spaces.

Automatically Adjust for Length Changes

If the sequence range changes, enabling this parameter will adjust the subrange and frame dropoff lengths to fit the new range.

Local variables

L	Sequence length
S	Start of sequence
E	End of sequence
IL	Input sequence length
SR	Sequence frame rate
NP	Number of planes in sequence
W,H	Width and height of image
I	Image index (0 at start frame)
IT	Image time (0 at start frame)
AI	Current plane array index
PI	Current plane index
PC	Num of channels in current plane
CXRES	Composite Project X resolution
CYRES	Composite Project Y resolution
CPIXA	Composite Project pixel aspect ratio
CDEPTH	Composite Project raster depth
CBP	Composite Project black point
CWP	Composite Project white point

Usages in other examples

Example name	Example for
Wipe	Blend compositing node	Load \| Launch
3d		Load \| Launch
flat		Load \| Launch