Stereo Camera Rig object

Provides parameters to manipulate the interaxial lens distance as well as the zero parallax setting plane in the scene.

Using the stereo camera rig

Press Tab with your mouse in the network editor.
Type Stereo Camera and choose it from the menu.
Select the newly created camera node from the camera menu in the top right corner of the viewport.

Note

You will see four entries, one for the right camera, one for the left camera, one for the center camera, and one for the whole stereoscopic rig. Choosing the stereoscopic rig node from that menu will initiate stereoscopic viewing in the viewport.
Lock the view and the camera by clicking the Lock Camera button on the right toolbar. This allows you to manipulate the viewpoint and direction while maintaining the stereoscopic composition.

Note

You will need a pair of standard red-cyan filter eye-wear, also known as anaglyph glasses, to perceive the stereo depth.

Tip

You can hide the viewport gnomons that obscure the view by selecting the appropriate checkboxes in the viewport display options.

Render the stereoscopic scene

Create a mantra render node and choose the stereoscopic camera rig for the Camera parameter.
Press the Render button to get an anaglyph preview in MPlay.

You can save the anaglyph by choosing File > Preview. You could also choose File > Save Frame or File > Save Sequence to separately save pairs of images which can be used in non-anaglyph stereo displays.

To save the left channel, choose the C plane in the Scope parameter of the Save dialog. To save the right channel, choose the C2 plane.

Note

The Output Picture parameter specifies the file name and a sequence of image pairs. These pairs can be used in other stereo displays or can be read using the File COP and fed into the Anaglyph COP node to create an anaglyph image sequence.

You can open a sequence of stereo images in MPlay by clicking File > Open Stereo Pair. MPlay combines the pair into a single anaglyph image and displays it as a frame.

Parameters

Transform

Keep Position When Parenting

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

Transform Order

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.

Translate

Translation along XYZ axes.

Rotation

Degrees rotation about XYZ axes.

Pivot

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

Look At

Object to point to. Constrains an object so its -Z axis always points at another object’s origin.

Look At Up Vector

When specifying a look at, it is possible to specify an up vector for the look at. This controls the roll of this object when looking at the look at object.

Don’t Use Up Vector	Use this option if the look at object does not pass through the Y axis of this object.
Use Up Vector	This precisely defines the direction of the Y axis of this object while looking. The up vector specified should not be parallel to the look at direction. The value used is specified by the Orient Up Vector parameter below.
Use Quaternions	Quaternions are a mathematical representation of a 3D rotation. This method finds the most efficient means of moving from one point to another on a sphere.

Path Object

A reference to the curve node or object you want this object to follow.

Roll

The orientation of the object around the path.

Position

The position of the object along the path. 0.0 means at the beginning of the path, and 1.0 means the end. The integer portion of the position is used as the primitive number inside the geometry while the fractional part indicates the u value on the primitive.

If the primitive number does not exist, then it is wrapped back to the beginning. So for numbers greater than 1.0 in a path object that only have a single primitive, it wraps around to the beginning again. You can easily animate something moving around a circular track simply by continuously increasing the position value.

Keyframe this value to animate the object moving along the path.

Note

The Follow Path tool on the shelf automatically sets keyframes on this parameter that you may want to edit or replace.

The Parameterization option controls how position values between 0 and 1 correspond to knots on the path curve.

Parameterization

Controls how the Position parameter is translated into a point on the path curve. Use Arc-length (the default) to interpolate the position values evenly along the physical length of the curve.

Use Uniform to distribute the position values between the knots of the curve. This lets you slow down the object at certain points by bunching up knots in the path curve. However, it is much more convenient to simply edit the animation curve to control the speed of the object along the path.

Orient Along Path

Orient the object according to the path’s curvature.

Orient Up Vector

The direction vector of the object’s Y axis to orient with.

Auto-Bank factor

Controls automatic banking of the object as it turns corners. Set this to 0 to turn automatic banking off.

Stereo

Zero Parallax Setting

Controls the distance to the ZPS plane measured from the camera.

The ZPS is a set of points in space whose left and right projections overlap at the same spot in the displayed image. The ZPS plane coincides with the viewing screen. Objects between the camera and the ZPS plane appear to the viewer in front of the viewing screen, and objects behind the ZPS plane appear to the viewer behind the viewing screen.

Interaxial Distance

Controls the separation distance between the left and right cameras and is directly visualized as part of the camera prop in the viewport. Increasing this parameter will push both Left and Right camera away from the center.

The Interaxial Distance is the separation between the left and right cameras. Large values produce a more pronounced stereoscopic effect with enhanced sense of depth, while small values reduce the sense of depth. A value of zero produces non-stereoscopic imagery.

Left/Right Interaxial Adjustment

Allows you to fine tune the left and right camera lenses. These parameters contribute to the overall Interaxial Distance for the stereo camera.

Show Interaxial Control

Displays the arrows near the camera lenses. Selecting and moving these objects increases or decreases the interaxial distance of the stereo camera. However, you will not see the interaxial controls if you are looking through the camera. To view and move the controls in the viewport, unlock the camera and switch to the object level. The controls act like Null objects.

Note

To modify the interaxial distance while looking through the camera, drag the Interaxial Distance parameter into the viewport and use the hudslider. To remove the slider, simply click and turn off the Display checkbox.

Show ZPS Marker and Screen Surround

Displays a frame corresponding to the physical screen when viewing the stereo images.

Screen surround is the left, right, top, and bottom edges of the viewing screen. This visualization helps position the objects in the scene relatively to the camera and the screen surround. Objects between the camera and screen surround visualization will appear to pop out of the screen towards the viewer.

Note

The screen frame can be selected and moved in the viewport to adjust the ZPS distance. Additionally, a ZPS arrow marker is displayed so that it can be used for adjustment when viewing through the stereo camera by selecting and dragging it along the z-axis.

Show Frustum

Displays several frustums.

Center	Displays frustum for the center camera.
Left	Displays frustum for the left camera.
Right	Displays frustum for the right camera.
Left and Right	Displays frustum for superimposed left and right frustums.
Intersection of Left and Right	Defines the region of space whose points are seen in both left and right images. Objects in this region will maintain the stereoscopic appearance, which has a tendency to break down for objects close the to left and right edges of the screen surround. For example, outside of this frustum.

Note

These frustums are delimited by the near and far clipping planes. These are independent parameters on the rig, but it is often customary to tie their values to the screen surround. For example, at 1.5% of the width away from the ZPS plane. This can be achieved in the Stereo Camera rig with appropriate channel references and multipliers in the near and far clipping plane parameters.

View

Icon Scale	Scales the viewport geometry. This parameter is only for display purposes.
Resolution	The output resolution in pixels. Standard presets are available via the pull down menu to the right of the parameter.
Pixel Aspect Ratio	Pixel aspect ratio (width/height) of the intended display device.
Focal Length	Camera focal length (zoom).
Focal Units	The units used for the focal length.
Aperture	Width of the visible field.
Near Clipping	Position of near clipping plane.
Far Clipping	Position of far clipping plane.
Screen Window X/Y	Define the center of the window during the rendering process.
Screen Window Size	Scale for expanding the cropped area specified by the Crop parameters.
Left/Right/Bottom/Top Crop	Defines the cropping area in terms of the camera’s viewing area margins.

Sampling

Shutter Time

The portion of the frame interval that the camera shutter is open. Used to determine motion blur. [0,1]

Focus Distance

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.

F-Stop

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

Bokeh

Filter kernel used in depth of field rendering.

radial	Use a gaussian filter kernel (highest quality)
box	Use a box filter kernal
null	Do not filter

Subnet

Display	Whether or not this object is displayed. Turn on the checkbox to have Houdini use this parameter, then set the value to 0 to hide the object, or 1 to show the object. If the checkbox is off, Houdini ignores the value.
Output Transform	The object inside the subnet from which to get the subnet’s output transform.
Visible Children	Space separated list of objects inside the subnet to display. Use `` to make all objects visible (the default). You can use wildcards and bundle references to specify objects. This parameter lets you: Quickly filter the visible objects based on an existing naming convention, for example `_proxy`. Control visibility of objects inside a locked digital assets where the display flags are not available. Otherwise, in a normal subnet you can simply go into the subnet and set the display flag on objects.
Viewport Selecting Enabled	Object is capable of being picked in viewport.
Select Script	Script to run when the object is picked in the viewport. See select scripts.
Cache Object Transform	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 OBJ cache preferences for how to control the size of the object transform cache.

Usages in other examples

Example name	Example for