The left menu chooses the order in which transforms are applied (for example, scale, then rotate, then translate). This can change the position and orientation of the object, in the same way that going a block and turning east takes you to a different place than turning east and then going a block.

The right menu chooses the order in which to rotate around the X, Y, and Z axes. Certain orders can make character joint transforms easier to use, depending on the character.

Translation along XYZ axes.

Degrees rotation about XYZ axes.

Local origin of the object. See also setting the pivot point .

This menu contains options for manipulating the pre-transform values. The pre-transform is an internal transform that is applied prior to the regular transform parameters. This allows you to change the frame of reference for the translate, rotate, scale parameter values below without changing the overall transform.

When the object is re-parented, maintain its current world position by changing the object’s transform parameters.

When the object is being transformed, maintain the current world transforms of its children by changing their transform parameters.

Enable Constraints Network on the object.

Path to a CHOP Constraints Network.

Whether or not this object is displayed in the viewport and rendered. Turn on the checkbox to have Houdini use this parameter, then set the value to 0 to hide the object in the viewport and not render it, or 1 to show and render the object. If the checkbox is off, Houdini ignores the value.

Use the specified wireframe color

The display color of the object

Object is capable of being picked in the viewport.

Script to run when the object is picked in the viewport. See select scripts .

Caches object transforms once Houdini calculates them. This is especially useful for objects whose world space position is expensive to calculate (such as Sticky objects), and objects at the end of long parenting chains (such as Bones). This option is turned on by default for Sticky and Bone objects.

See the OBJ Caching section of the Houdini Preferences window for how to control the size of the object transform cache.

Scales the viewport geometry. This parameter is only for display purposes.

The output resolution in pixels. Standard presets are available via the pull down menu to the right of the parameter.

The pixel aspect ratio of the output image.

Type of camera projection used for rendering (for example, perspective or orthographic).

Lens Shader: Use a lens shader to initialize rays for ray tracing.

Selecting Polar, Cylindrical or Lens Shader will automatically switch the Rendering Engine (on the output driver) to Ray Tracing, as it is impossible to render these projections with micropolygon rendering.

Specifies the CVEX lens shader to use for the Lens Shader projection type. A lens shader is responsible for computing primary rays from screen coordinates, and is a flexible way to define new kinds of camera projections that can’t be modeled as perspective or orthographic projections. Lens shaders can have the following parameters and exports:

The lens shader should be able to handle x and y values outside the -1 to 1 range, in case samples outside the image need to be generated. The P and I exports should be created in camera space, ignoring the camera transform.

Before rendering begins, mantra measures the lens shader before rendering. During the measuring process, the valid variable can be used to flag invalid rays. In the future, the valid flag may be used during rendering.

Mantra’s camera space is defined with positive z-values in front of the camera, so for a default camera the z-axis is flipped relative to Houdini’s world space.

An example lens shader is the Ray Lens shader.

Camera focal length (zoom).

The units used for the focal length.

Width of orthographic view volume when using Projection is set to Orthographic.

Position of near clipping plane.

Position of far clipping plane.

Define the center of the window during the rendering process.

Scale for expanding the cropped area specified by the Crop parameters.

Sets the screen window mask to cover the bounding box of the selected object(s).

Left cropping margin for camera’s view area.

Right cropping margin for camera’s view area.

Bottom cropping margin for camera’s view area.

Top cropping margin for camera’s view area.

Sets the pixel crop region to cover the bounding box of the selected object(s).

The shutter time refers to the portion of a frame the shutter is actually open. On a physical camera, this if often referred to as Shutter Speed. The renderer uses this determine motion blur. The value should be in the range [0,1].

A value of 0 for the shutter time would mean that there is no motion blur at all, as the shutter is only “Open” for an instant. A value of 1 on the other hand would mean that the shutter is open for the entire length of the frame.

In the above example the sphere is rotating a full 360 degrees over the course of a single frame. You can see how the length of the “motion trail” or “blur” changes based on the shutter time. In most cases, the default value of .5 is appropriate for animated sequences and a good match for real world settings.

Keep in mind that this parameter controls the amount of time within a single frame, that the shutter is open. It does not refer to how long an individual frame is. To adjust the frame rate, change the Frames per Second parameter in the Global Animation Options.

The lens focal distance and distance from the camera at which objects will be in focus. This is only used when rendering using depth of field. Objects outside this distance will be blurred.

Lens fstop. This is only used when rendering using depth of field. Determines blurriness of depth of field effects.

Filter kernel used in depth of field rendering. Use the pop-up menu to the right of the text box to choose from the available options.

The file to use for “file” shaped bokeh. White/black cutout images that delineate the shape of the lens are good candidates, where white regions represent the areas that light passes through.

The rotation for “file” shaped bokeh.