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Parameters are the options of a node. Changing the parameters changes the look or behavior of the node. For example, a Sphere SOP has position and radius parameters.


Node menu

Shows the icon of the node you are currently editing. Click to show the node’s context menu. (This is the same menu you get if you press on the node’s tile in the network editor


The node’s name. When you create a node it has a default name of the operator type name plus a number. You can edit the textbox to change the node’s name (this is the same as clicking the name next to the node’s tile in the network editor). Node names can only contain letters and numbers. Spaces are not allowed in the name.

Gear menu

Use the items in this menu to Load and save parameter presets.

  • Edit the node’s parameter interface. See the Edit Parameter Interface window.

  • Save presets. Once you save a preset

  • Edit the node’s delete script (this lets you define a script that Houdini will run if/when the node is deleted).

  • Edit the node’s comment string.

Help (question mark)

Click to view documentation of the node’s parameters.

Text box color coding

Background color


Light Green

The parameter is controlled by an expression, and the current frame is a keyframe.


The parameter is controlled by an expression but the current frame is not a keyframe (or the channel value at the current frame is disabled from the dopesheet).


Pending keyframe (the current value at this frame is different from the keyed value, but you have not yet keyframed it).


The parameter is currently controlled by a channel operator (CHOP).


Angle icon

For edit fields which accept angular measurements, type the number of degrees in the edit field or press and drag on the angle icon to set the angle graphically.

Polar jack

For edit fields which accept angular measurements, type the number of degrees in the edit field or drag the small point at the intersection of the two rings in the polar jack.

Input list

Some operators, such as the Merge SOP and Switch SOP, allow multiple inputs to their single input connector. In these operators, an input list appears in the parameters, where you can reorder or disconnect any of the inputs.

Color controls

Parameter pop-up menu

Toggle Expression

Switch the text box between showing the computed value for the current frame and the expression itself.

HUD Sliders

Step to Prev/Next Key, Set/Remove Keyframe

Copy Parameter, Paste Copied ..

Scope Append Channels, Scope Channels

Show the parameter(s) in the animation editor.

Delete Channels

Removes any animation on the parameter, making it a static, constant value.

Parameter RMB menu

Revert to Previous Value

Return to the previous parameter value.

Channels and Keyframes

Options for scoping parameters as well as setting and removing keyframes.

Scope Append Parameters

Appends the parameter to the Scoped Parameter List.

Scope Parameters

Scopes the parameter to the Scoped Parameter List clearing its previous content.

Set Keyframe

Sets a keyframe at the current time on the parameter.

Remove Keyframe

Removes keyframe at the current time on the parameter.

Step to Previous/Next Key

Change the current time to the time of the previous or next keyframe on the parameter.

Edit Channel Properties

Opens an Edit Channel Properties dialog to edit Channel Aliases, Colors, Auto-Scope flags and Before/After Extrapolation ( Hold, Slope, Cycle, CycleOffset )

Set/Unset Auto Scope

Modifies the Auto-Scope flag on the parameter.


Additional menu with options for working with expressions.

Motion Effects

Options for motion effects such as: Cycle, Cycle with Offset, Despike, Lag, Limit, Noise, Shift, Smooth, Spring, Stretch, and Wave.

Copy Parameter

Copies the parameter to the clipboard.

Paste Copied Values

Pastes in the values of the parameter on the clipboard. If you copied parameters with expressions, this will paste the computed values of the expressions.

Paste Copied Expressions

Pastes the values and expressions of the parameter on the clipboard. Does not convert expressions to values.

Paste Copied References

Pastes a reference to the copied parameter (using the ch expression function). Unlike pasting a copy of the value of the other parameter, this expression will fetch the other parameter’s value every time it is evaluated, so it stays up to date with the current value of the other parameter.

This command inserts an expression with an absolute path to the copied parameter. To insert a relative reference instead, use Paste Copied Relative References.

Paste Copied Relative References

Same as Paste Copied References, but the ch expression uses a relative path to the copied parameter, instead of an absolute path.

Paste Copied Channels

Pastes a copy of the channel. Once the channel is pasted, it is independent from the original channel and can be modified without altering the original.

Include in Take

Adds the parameter to the take. For more information on takes, see Create variations with takes.

Lock/Unlock Parameter

Locking a parameter protect it from being edited.

Revert to Defaults

Resets the value to the current default. If you have changed the default value with Make Current Value Default, it will be reset to this value, not the default value that ships with Houdini.

Revert to and Restore Factory Defaults

Resets defaults to the ones that ship with Houdini.

Make Current Value Default

Makes the current value the default so that every time you create a new node it will have the new default value.

Export Parameter to Type Properties

Adds parameter to the Existing Parameter list in the Operator Type Properties dialog.