Houdini 11 Nodes Compositing nodes

Computes the gradient of an image.

Computes the gradient of the image, which indicates the direction of greatest luminance increase in UV. The map produced looks like a bump map.

The different maps produced by this operation are:

• UV Gradient - Computes the UV gradient of the image, which is a 2D vector which points in the direction of greatest luminance increase. The magnitude of the vector is the increase amount. Similar to the results produced by the Bump COP.

• Normal Map - Computes a normal map from the gradient. The normal and the gradient are similar: the normal is a normalized 3D vector with the Z component set to 1 and X & Y set to the U & V values of the gradient.

• Gradient Magnitude - Computes the gradient magnitude, which appears as a luminance edge-detected image.

• Thresholded Magnitude - Computes the gradient magnitude and only accepts values between the low and high threshold values. If normalize is on, the values are mapped from low to high to 0 to 1.

Parameters

The channel used to compute the gradient.

Output

The type of output produced:

 UV Gradient Computes the UV gradient of the image, which is a 2D vector which points in the direction of greatest luminance increase. The magnitude of the vector is the increase amount. Similar to the results produced by the Bump COP. Normal Map Computes a normal map from the gradient. The normal and the gradient are similar: the normal is a normalized 3D vector with the Z component set to 1 and X & Y set to the U & V values of the gradient. Gradient Magnitude Computes the gradient magnitude, which appears as a luminance edge-detected image. Thresholded Magnitude Computes the gradient magnitude and only accepts values between the low and high threshold values. If normalize is on, the values are mapped from low to high to 0 to 1.
Low/High Threshold

The low and high thresholds for thresholded magnitude output.

Normalize

If UV Gradient output is used, this normalizes the gradient’s magnitudes to 1. If Thresholded Magnitude is used, this maps the low to high range to 0 - 1.

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).

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.

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

```

```            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).

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.

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

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.