Stereo lenses information

Maxwell Studio LatLong Stereo

Lat-Long Stereo Shader Controls

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Lens

Near the top of the Optics section is a Lens attribute that lets you switch the current lens shader model.

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In this section we are focusing on the Lat-Long Stereo lens model that outputs a latitude longitude format stereo image that is also called an equirectangular or spherical format.

A Lat-Long image usually covers a 360 ° horizontal x 180 ° vertical area and is rendered to a 2:1 aspect ratio like 2048x1024 px, 3072x1536 px, 4096x2048 px, or 8192x4096 px.

Camera

• Type: lets you choose whether the lens shader will output either the center view (which has the stereo settings disabled), or you can choose to render a left or right stereo camera view.

• FOV Vertical: Controls the vertical FOV angle (in degrees) of the rendered Latitude/Longitude image.

• FOV Horizontal: Controls the horizontal FOV angle (in degrees) of the rendered Latitude/Longitude image.

• Separation: The initial camera separation of the left and right cameras in centimeters. This value would typically be set to a number between 6 to 6.5 centimeters for a real world scale scene.

  For a "Hyperstereo" effect that can make the details in the distance pop up more the separation value can be increased greatly as long as objects aren't placed to close to the camera as this would cause eye strain.

  You can also reduce the cameras separation attribute and the parallax distance smaller if you are placing objects close to a scene or rendering a scene set in a tiny microscopic world.

  This stereo effect is typically reduced at the pole regions using the separation map texture to remove a "swirl" artifact that would otherwise occur.

• Zenith Mode: This attribute allows you to adjust the Lat-Long Stereo 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 Fisheye Stereo shader.

• Separation map: A texture attached to this control has an effect of multiplying a 0-1 range value against the current camera Separation attribute. This texture map control is meant to be used with an RGB image that has a black to white style grayscale texture applied. The image is used to control the amount of 3D effect, and eliminate it where desired. A texture attached to this control has an effect of multiplying a 0-1 range value against the current camera Separation attribute.

  This texture map control is meant to be used with an RGB image that has a black to white style grayscale texture applied. The image is used to control the amount of 3D effect, and eliminate it where desired. It feathers out the stereo effect in the pole regions in a lat-long rendering. The zenith or upwards sky facing pole region is at the top of the texture map, and the nadir or downwards facing pole region is on the bottom of the texture map. Those two singularities usually look wrong creating a swirl effect and it’s better to eliminate them with a texture like this:

Image

• Flip X: This checkbox will flip the view horizontally.

• Flip Y: This checkbox will flip the view vertically.

Parallax

This control adjusts the distance in the scene where the depth converges in the left and right eye views.

Objects placed closer to the camera than the Zero Parallax Distance appear to come out at the audience. Objects placed further away from the camera than the Zero Parallax Distance value appear to the viewer as if they are existing beyond the physical "wall" of the screen they are viewing.

This Parallax Distance control is measured in centimeters (cm) so you should enter a starting value of 360 units if you are using a typical 6.5 cm camera separation value.

Maxwell Studio Fisheye Stereo

Fisheye Stereo Shader Controls

Lens

Near the top of the Optics section is a Lens attribute that lets you switch the current lens shader model.

In this section we are focusing on the Fish Stereo lens model that outputs an angular fisheye format stereo image that is also called a domemaster frame if the field of view is set to 180 degrees (diagonally measured), or a light probe / angular map if rendered to a 360-degree field of view (diagonally measured).

An angular fisheye image is typically rendered to a 1:1 aspect ratio like 2048x2048 px, 3072x3072 px, 4096x4096 px, or 8192x8192 px.

Type

The type attribute lets you choose whether the lens shader will output either the center view (which has the stereo settings disabled), or you can choose to render a left or right stereo camera view.

Field of View

The field of view control adjusts the focal length of the angular fisheye rendering. By default, a full dome image has a 180-degree field of view.

If you want to include a bit of the "ground" in the scene, it is possible to increase the field of view slightly to a value like 220 degrees and the final rendered image will still look acceptable in a dome.

Tip: If you want to render a full 360-degree angular fisheye image which is also known as an HDRI light probe you will need to update the custom maps that are applied to the stereo separation, and turn attributes.

Separation

This controls the camera separation / stereo base of the stereo camera rig and is always measured in centimeters in Maxwell Studio.

This value would typically be set to a number between 6 to 6.5 centimeters for a real-world scale scene.

Separation Map

A texture attached to this control has an effect of multiplying a 0-1 range value against the current camera Separation attribute.

This texture map control is meant to be used with an RGB image that has a black to white style grayscale texture applied. The image is used to control the amount of 3D effect, and eliminate it where desired.

This is a typical separation map for a Fisheye lens:

The 180-degree angular fisheye separation map texture may look a bit strange but what it is indicating is the area just behind the viewer's head when seated in a dome theater has the stereo effect reduced where the viewer may be fully tilted back in their chair and looking back past the top pole region of the theater.

Vertical Mode

The vertical mode control can be used if you have a curved full dome screen that is mounted vertically against a wall and the viewers look forward at the screen.

Head Turn Map

A texture attached to this control has an effect of controlling the head rotation as the panoramic image is rendered. This is especially important in the pole regions of an angular fisheye frame.

This texture map control is meant to be used with an RGB image that has a black to white style grayscale texture applied. The image is used to control the amount of 3D effect, and eliminate it where desired.

This is a typical head turn map:

The turn map image is used to take care of the stereoscopic effect at the zenith area directly above the viewers' head. The texture map removes a swirl effect that would be present without the turn control setting.

The turn map can be used to take care of the area 180 degrees behind the viewer where the stereoscopic effect would be reversed if the viewer rotated their head to look at the back of the full dome screen.

It is also is used to control the lens shaders panoramic stereo rendering mode where you can keep the stereoscopic orientation of a fisheye rendering facing forwards in the pole region.

Head Tilt Map

A texture attached to this control has the ability to adjust the stereo rendering method and push the pole region backwards past the zenith area.

This texture map control is meant to be used with an RGB image that has a black to white style grayscale texture applied. The image is used to control the amount of 3D effect, and eliminate it where desired.

This is a typical head tilt map:

The head tilt map has two shaded areas that are used to cause the stereo rendering settings in the lens shader to adjust for the fact a seated viewer in the planetarium theater is rolling their head at a slightly tilted angle when looking to the far left or far right area on the "front half" of the dome screen.

The neutral value for the head tilt map is a 50% grey color in the RGB image.

Parallax Distance

This control adjusts the distance in the scene where the depth converges in the left and right eye views. It’s a bit like controlling the dome radius.

Objects placed closer to the camera than the parallax distance appear to come out at the audience. Anything located in and around the parallax distance appears in stereoscopic 3D as if it is sitting right on the wall of the full dome theater screen. Objects placed further away from the camera than the parallax distance value appear to the viewer as if they are existing beyond the physical wall of the planetarium screen.

Neck controls

These controls let you set a forward distance from the center of rotation of the camera to simulate the distance of the eyes from the head rotation point. It helps avoiding motion sickness.