camera_type 

Arnold provides the following camera types: 

 

The camera can already have a type assigned, in which case "from camera location" is what should be used. Only change the camera type to override what is already set on the camera previously.

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). 

-2
0 (default)
2

adjustAspect

Used to control whether the global aspect ratio adjustments for resolution and pixel aspect are included on the camera. Cameras used for rendering pixels always include this, but other cameras (e.g. for projection) by default do not include this adjustment.

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

uv_remap

This parameter takes a 2D displacement image and uses it to distort the rendered output of the camera's lens. The left image below has been rendered using a colored ramp connected to the UV Remap attribute. In the right image, the same ramp texture has been distorted in a 2d image post-processing software package.

UV Remap
Remap image has been distorted

When using uv_remap you should use the image shader's 'image.swrap clamp' and 'image.twrap clamp' attributes to minimize edge effects due to filtering.

radial_distortion

Radial distortion, with negative and positive values resulting in pincushion and barrel distortion respectively. Real-world lenses can show such distortion when using, for example, a very short focal length or a high zoom.

-0.1 (pillow distortion)
0 (no distortion)
0.3 (barrel distortion)

Radial Distortion (-1.3 to 1)

 

A 'barrel distortion' camera lens effect has been reproduced in the interior scene below, by simply increasing the Radial Distortion to 0.2 (rollover image).

Rollover image

 

subdiv_dicing_camera

This camera location will be used for any adaptive subdivision when the subdivision is based on edge length.  This avoids popping artifacts for adaptive subdivision.

Motion Blur

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

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'. 

Top
Bottom
Left
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).

0 (default)
0.05
0.1


output_motion_vectors

Outputs motion vectors. More information about motion vectors can be found here.

Depth of Field

focus_distance

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

6
8
10

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. 

0.1
0.2
0.3


aperture_blades

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

3
5
7

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.

0
1 (default)
10
 

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.

0
1

aperture_rotation

Rotates the aperture by the specified number of degrees. 

0 (default)
15
30


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.

 

adjustAspect

Interprets the aspect ratio from the image resolution, as well as the pixel aspect ratio from the named resolution in RenderSettings. It defaults to making no adjustments for image aspect but applies the pixel aspect ratio from RenderSettingschosen resolution. The various choices can choose to adjust for image aspect, and or the RenderSettings resolution's pixel aspect ratio when they are non-square. For all choices except "no adjustments" KtoA will properly embed the pixel aspect ratio into any rendered EXR/TIFF metadata.

overridePixelAspectRatio

Overrides the pixel aspect ratio directly to e.g. anamorphic formats when that isn't set in the resolutions XML file for the given resolution. This aspect ratio is the pixel width divided by the pixel height and is effectively applied by adjusting the viewable aperture on the camera by Arnold itself. The pixel aspect ratio is embedded as metadata in any rendered TIFF/EXR images.

 

 

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