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Arnold MtoA LatLongStereo
The LatLongStereo shader is added to a Maya scene using the ArnoldDomemaster3D Shelf tool.
When you run the LatLongStereo shelf tool it adds a custom ArnoldLatLongStereo camera rig to the scene that has the left and right cameras set up automatically. The left camera LatLongStereo attributes are used to drive the stereoscopic settings for both the left and right cameras. This means you only have to change the Zero Parallax Distance or Camera Separation setting in one place.
To change the LatLongStereo attributes, select the camera in your scene. Open the attribute editor and switch to the camera's shape node. The lens shader is listed in the Arnold section.
Arnold 5 Compatibility Note: The new Arnold 5 release has changed their lens shader system. At this point in time the current Domemaster3D shaders are not compatible with Arnold 5. If you need a lens shader today that works with Arnold 5 it is recommended you use the new built-in "VR Camera" module provided by Solid Angle directly.
The current version of the Arnold Domemaster3D shaders for Maya are a development build. At this point in time there is no easy way to create screen space texture maps using Arnold's MtoA, HtoA, C4DtoA, and SItoA render nodes. This means a solution has to be developed inside the Domemaster3D shaders that will remap an existing texture map into screen space coordinates.
The LatLongStereo shader generally works fine. The only thing to note is that there is no way to feather out the stereo effect in the zenith and nadir zones using the separation map attribute. The LatLongStereo shader should be rendered with a 2:1 aspect ratio to avoid vertically over-rendering the scene's FOV angle.
Also the LatLongStereo shader expects a 2:1 aspect ratio render resolution for the output. The code to compensate for a non 2:1 rendered aspect ratio hasn't been finished yet so you will experience over-rendering of the FOV if you render to an image with a 1:1 aspect ratio.
LatLong Stereo Shader Controls
Camera: Choices are Center/Left/Right. Selects the camera to use for rendering. Center skips 90% of the calculations and gives you a highly optimized standard latlong image.
Field of View Vertical: Controls the vertical FOV angle (in degrees) of the rendered Latitude/Longitude image.
Field of View Horizontal: Controls the horizontal FOV angle (in degrees) of the rendered Latitude/Longitude image.
Zero Parallax Distance (focus plane): This is the distance at which the left and right camera's line of sight converges.
Camera Separation: The initial separation of the left and right cameras.
Zenith Mode: This attribute allows you to adjust the
LatLongStereo lens shader to work with either a horizontal orientation (Zenith Mode OFF), or an upwards / vertical orientation (Zenith Mode ON) that lines up with the upright view orientation of the
Domemaster Stereo Shader shaders.
Separation Map: A value between 0-1 that multiples the Camera Separation. This attribute is meant to be used with a grayscale texture mapped to the screen space. It's used to control the amount of 3D effect, and eliminate it where desired.
Flip X: Flips the view horizontally
Flip Y: Flips the view vertically
Exposure: This attribute allows you to control the overall brightness of the final rendered frame.
Screen Space Texture Maps
You can control the stereoscopic effect seen in the LatLongStereo and DomemasterStereo shaders with the help of control texture maps.
The LatLongStereo shader's Separation Multiplier attribute supports control texture mapping. The image has to be applied using screen space coordinates.
Comfortable Stereo Settings
Here is a little tip that will help you work out some initial "comfortable" stereo settings to use in the Domemaster3D lens shaders:
Use Maya's distance measurement tool to check how far it is in the top view from the stereo camera to your main object of interest like a character, or to about the middle point depth wise in the scene from the camera's point of view.
Select the stereo camera rig's left camera in the Maya outliner. Enter the distance value you measured as the "Zero Parallax Distance" in the Attribute Editor.
Then take your Zero Parallax Distance and divide it by 120 and enter this resulting number in the Camera Separation attribute in the lens shader. This should get the stereoscopic effect to be in the rough "ballpark zone" that is comfortable for the viewer regardless of what scene unit size you modeled your Maya project using.