cameras

Common Parameters

The following parameters are the same for all of the camera nodes.

position

The position of the camera.

look_at

The point at which the camera is pointing.

up

The up vector of the camera.
matrix

Matrix to define the position and orientation of the camera. 

near_clip

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

far_clip

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

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.

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.

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

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

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

rolling_shutter_duration

With this parameter, it is possible to control the duration of exposure of the scanlines in a rolling shutter camera. Valid values for this parameter are in the 0 to 1 range, where a value of 0 gives you an instantaneous exposure of each scanline (the default value and the rolling shutter's previous behavior), and a value of 1 exposes every scanline for the entirety of the camera's shutter interval (the same result that a camera without rolling shutter would give).


handedness

Chooses the "right" handed or "left" handed coordinate system.

screen_window_min

 

screen_window_max

These define the 2d window in the projection plane that will be rendered. If set to their 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.

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). 

Depth of Field

The following parameters are common to the perspective and fisheye camera nodes.

focus_distance

This is the distance at which objects appear in perfect focus, for a non-zero aperture value.

aperture_size

The radius of the aperture in world units. The smaller the aperture, the sharper the images (shallower depth of field). In the limit, a size of zero produces no depth of field blurring.

aperture_blades

A number of blades (or polygon sides) of the polygonal aperture. 0 is considered a circle aperture

aperture_rotation

Rotates the aperture by the specified number of degrees. 


aperture_blade_curvature

The curvature of the polygonal aperture sides. A value of 0 means hard straight sides. Increasing this value results in progressively more curved edges, all the way to 1.0 which produces a perfect disk. Negative values produce a "pinched" or star-shaped aperture.

aperture_aspect_ratio

Values bigger than one produce an elongated defocusing effect, reminiscent of an anamorphic lens, while a value less than one will squash it.

 

flat_field_focus

This parameter matches the standard thin lens camera model. This prevents over blurring away from the optical axis. Some renders might change, especially with wide FOV angles or very shallow DOF. Set persp_camera.flat_field_focus false to get the previous behavior.

 

 

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