Class

Camera

Synopsis

 

Scene rendered with spherical_camera lens


This is a spherical camera which means that the camera lens has a spherical appearance. A common use of this camera projection is to allow the creation of environment maps (in spherical map format) for later use as reflection maps or for environment lighting. To get the full spherical range, the camera's screen window must be set to [-1,-1] to [1,1]. Note that the same mapping could be achieved in the cylindrical camera with careful setting of the Horizontal FOV, Vertical FOV, and Projective parameters but the spherical camera is provided for convenience.




position

The position of the camera.  (common)

look_at

The point at which the camera is pointing.  (common)

up

The up vector of the camera.  (common)

matrix

Matrix to define the position and orientation of the camera.   (common)

near_clip

The near clipping plane of the camera's renderable area.  (common)

far_clip

The far clipping plane of the camera's renderable area.  (common)

shutter_start

Defines when the camera shutter is open. The shutter range is normalized to 0 and 1. shutter_start of zero would equal to the first motion blur key while a shutter_start of one would equal to the latest motion blur key.  (common)

shutter_end

Defines when the camera shutter is closed. The shutter range is normalized to 0 and 1. shutter_end of zero would equal to the first motion blur key while a shutter_start of one would equal to the latest motion blur key. The shutter_end must be bigger than the shutter_start.  (common)

shutter_type

The filtering applied to time samples. By default, this is a box filter, with all time samples having the same weight. A triangle (or "tent") filter is also available which produces smoother trails.

Arnold supports custom shutter shapes with the shutter curve camera parameter. You can define as many points as required. Coordinates increase from 0 (corresponding to the shutter_start) to 1 (corresponding to the shutter_end). Values in the vertical axis must be non-negative, and it is not recommended to enter values above 1. The values are linearly interpolated between each point. In the examples below, you can see the effect different curve shapes have on the motion blur trail of a sphere that has been key-framed moving from left to right.

Various custom camera shutter curve shapes

  (common)

rolling_shutter

Rolling Shutter is used to simulate the type of rolling shutter effect seen in footage shot with digital cameras that use CMOS-based sensors such as Blackmagics, Alexas, REDs, and even iPhones. This method is implemented by rolling (moving) the shutter across the camera area instead of the entire image area all at the same time. 

Without rolling shutter (rollover image).

With rolling shutter (rollover image).

 

The Rolling Shutter direction specifies the direction that the rolling shutter takes place. The default is 'off'' and can be set to 'top' (top to bottom being the most common scanning direction), 'bottom', 'left' or 'right'. 

 

Interesting effects can be achieved when combining motion blur 'length' with rolling shutter:

Motion blur 'length' from 0 to 2

  (common)

filtermap

Weights the camera sample by a scalar amount defined by the shader linked to the filtermap. This shader will use as an input, u,v coordinates in image-space coords [0,1) and x,y in pixel coordinates. This allows you to darken certain regions of the image, perfect to simulate vignetting effects.

There is an optimization in place where if the filter returns pure black then the camera ray is not fired. This can help in cases such as when rendering with the fisheye camera where, depending on its autocrop setting, parts of the frame trace no rays at all.

Circular ramp mapped to the camera's filtermap to create a vignette effect

  (common)

handedness

Chooses the "right" handed or "left" handed coordinate system.  (common)

screen_window_min

This defines the 2d window in the projection plane that will be rendered. If set to its default (-1,-1) (1,1) the frame will exactly match with the defined region, after taking aspect_ratio into account so that there is no distortion. These should be set if you want to stretch, squash, or zoom to a particular area in an image.  (common) 

screen_window_max

This defines the 2d window in the projection plane that will be rendered. If set to its default (-1,-1) (1,1) the frame will exactly match with the defined region, after taking aspect_ratio into account so that there is no distortion. These should be set if you want to stretch, squash, or zoom to a particular area in an image.  (common)

exposure

Simulates the effect of camera exposure (in a non-physical way). Increasing this parameter by a value of one gives you one stop up (doubles the brightness). 

(common)





Workflow Example


Below is an example of a spherical camera lens. The image below shows a studio lighting rig scene. The spherical camera can be used to convert this scene into a spherical HDRI that can be used with the skydome_light.

The chrome sphere is there for demonstration only and is not needed when rendering a spherical camera map.


  • Position the camera in the center, in order to convert the scene into a spherical camera image. 

Light texture maps have been assigned to the reflector planes (textured light sources will not be visible to the camera).

The image below is a render of the spherical camera in the center of the scene. The scene must be rendered at a high enough resolution and the pixel aspect ratio should be set to 1, otherwise, distortions may appear in the reflections of the scene.

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