LensDistortion

Displays the GPU used for rendering when Use GPU if available is enabled. Local GPU displays Not available when:

• Use CPU is selected as the default blink device in the Preferences.

• no suitable GPU was found on your system.

• it was not possible to create a context for processing on the selected GPU, such as when there is not enough free memory available on the GPU.

You can select a different GPU, if available, by navigating to the Preferences and selecting an alternative from the default blink device dropdown.

NOTE:   Selecting a different GPU requires you to restart Nuke before the change takes effect.

When enabled, rendering occurs on the Local GPU specified, if available, rather than the CPU. The output between the GPU and CPU is identical on NVIDIA GPUs, but using the GPU can significantly improve processing performance.

Nuke supports AMD GPUs on late 2013 Mac Pro 6,1, mid 2015 Mac Pro 11,5, and and late 2016 MacBook Pro 13,3, running OS X 10.9.3 'Mavericks', or later. While, in some cases the bit-wise equality between GPU and CPU holds, for some operations there are limitations to the accuracy possible with this configuration.

NOTE:  Enabling this option with no local GPU allows the script to run on the GPU whenever the script is opened on a machine that does have a GPU available.
You should also select this if you wish to render from the command line with the --gpu option.

GPU processing also requires certain NVIDIA and AMD drivers. For more information on the minimum requirements, please refer to the Nuke Release Notes.

Lens

Sets the lens type used to shoot the sequence:

• Spherical

• Anamorphic

• Beam Splitter

Sets the projection type, either Rectilnear or Fisheye. Fisheye offers several sub-types:

• Stereographic

• Equidistant

• Equisolid

• Orthographic

Sets the distortion model to use and adds or removes Distortion Parameter controls depending on the preset selected:

• NukeX Classic - uses the distortion model from legacy versions of Nuke.

• CaraVR Radial, Degree 3 - uses a distortion model suitable for CaraVR.

• 3DEqualizer - provides several distortion models suitable for 3DE.

• Custom - allows you to customize the distortion model from scratch.

Projection Parameters - These controls are only displayed when the Projection control is set to a Fisheye sub-type.

Sets the camera focal length (in mm).

Sets the size of the camera sensor (in mm).

Anamorphic Parameters - These controls are only displayed when the Type control is set to Anamorphic.

Sets the anamorphic squeeze used to rescale the x coefficients in the Distortion Parameters.

Compensates for lens twist, measured in degrees.

Compensates for lens breathing, the slight changes in focal length when changing the focus.

Distortion Model

Sets the distortion model type, though selecting a Preset alters the selection as appropriate:

• Radial Standard

• Radial Asymetric

• Radial Tangential

Sets the order of the radial distortion's rational polynomial function.

The first term controls the numerator order and the second controls the denominator order.

NOTE:   The default values (0, 2) correspond to the legacy NukeX model.

Sets the base exponent of the radial distortion polynomial.

The first term controls the numerator exponents and the second controls the denominator exponents.

NOTE:  A base exponent of 2 for the denominator corresponds to the classic NukeX model.

Set the distortion model direction:

• Forward - estimated directly but needs to be inverted for image rendering.

The NukeX Classic model is an example of a Forward model.

• Backward - estimated using its inverse but can be used directly for image rendering. Model inversion is not an exact process and may cause loss of information due to approximations.

The CaraVR Radial model is an example of a Backward model.

Sets the projection domain in which distortion is represented when 'defishing' a fisheye lens:

• Source - distortion is removed before projection is taken into account, before defishing.

• Rectilinear - distortion is removed after projection is taken into account, after defishing.

Sets how the focal length and distortion parameters are normalized:

• Width

• Height

• Diagonal

• Maximum

Distortion Equations

Distortion model equation display.

Legend: (xd, yd) are the distorted cartesian coordinates, (rd, phid) are the distorted polar coordinates, (xu, yu) are the undistorted cartesian coordinates, (ru, phiu) are the undistorted polar coordinates, and the k-values are the distortion coefficients. The coordinate systems are relative to the distortion centre.

Distortion model equation display.

Legend: (xd, yd) are the distorted cartesian coordinates, (rd, phid) are the distorted polar coordinates, (xu, yu) are the undistorted cartesian coordinates, (ru, phiu) are the undistorted polar coordinates, and the k-values are the distortion coefficients. The coordinate systems are relative to the distortion centre.

Distortion Parameters - dependent on the Distortion model preset applied.

Sets the denominator coefficients for the symmetric coefficients (s) of the distortion model.

Sets the numerator coefficients for the symmetric coefficients (s) of the distortion model.

Sets the position of the distortion center.

Keyframes

Displays the current keyframe number.

The LensDistortion node creates a keyframe at the beginning of the sequence automatically.

Displays the total number of keyframes.

Click to jump to the previous keyframe.

Click to jump to the next key frame.

Click to add a keyframe at the current frame in the sequence.

Click to delete the keyframe at the current frame in the sequence.

Sets the interval between keyframes for the Key All button.

Click to add keyframes to the sequence at intervals set by the Step control.

Click to delete all keyframes from the sequence.

Analysis

Click to run the selected detection method on all key frames for a calibration grid shot.

Grid detection consists of feature detection and feature linking. It can be run in one step, using Grids detection, or broken down into two steps to allow for manual corrections.

See the Grid Detection controls for more information on changing the detection parameters.

Sets the detection type executed by the Detect button:

• Features - resets the detection state and finds saddle points in the input grid shot.

• Links - connects detected features to form a grid. This runs Features detection first if it has not been already been executed.

• Grids - runs the Features and Links detection steps without allowing you to apply manual corrections between the two.

Click to estimate the distortion model parameters using the detected grids.

The solver attempts to warp the distorted links into straight lines.

NOTE:  Solving the distortion model requires at least as many feature links as parameters in the distortion model. If the Detect method doesn't find enough links, try adding more keyframes or tuning the detection parameters.

Click to reject links for which the residual error is outside the error Threshold.

You can delete outliers drawn red in the overlay and then click Solve again to improve the results by refining the warp.

You can also delete links manually by selecting them and pressing the Delete or Backspace keyboard shortcuts. Holding Ctrl/Cmd while deleting links keeps only the selected links.

Resets the distortion parameters and solve state. Deleted features and links are not restored.

Displays the root mean square (RMS) solve error in pixels.

This can be used to measure the quality of the solve. It is computed as the average deviation to an ideal straight line for each link. Move the mouse over a link to display its individual residual error.

Sets the error threshold for outliers rejection.

Lower values can produce a closer fit, but with the risk of overfitting. Too many outliers can be an indication of an issue with the selected distortion model.

Output

Sets the type of output from the node:

• STMap - renders both undistortion and redistortion STMaps in the motion channels. Use the forward channels for undistorting and the backward channels for redistorting. The other input channels are copied to the output directly. In this mode, the overlay grids can be displayed on top of the source image.

• Undistort - undistorts the input directly in the Viewer, allowing to visualize the undistorted overlay grid.

• Redistort - redistorts the input directly in the Viewer, allowing to visualize the redistorted overlay grid.

When enabled, lens projection is considered as part of the distortion when warping fisheye lenses.

When disabled, Nuke renders an 'ideal' fisheye without distortion when undistorting, and applies distortion to a fisheye image when redistorting.

NOTE:  This control has no effect on Rectilinear lenses.

When Mode is set to Undistort or Redistort, sets the image resampling filter to use.

As a general guide line, the filters increase in quality at the cost of processing time as you move down the list. Nearest filtering is the fastest and Lanczos the sharpest.

Sets the rescaling mode:

• Input - use the input format for the output. This also uses the input format to scale the distortion.

• Rescale - use the selected Format to rescale the distortion. This sets the output format to the input format.

• Reformat - reformat the output with the selected Format. This uses the input format to scale the distortion.

Sets the format to use to reformat the image or to rescale the distortion when Scaling is set to Rescale or Reformat.

Adjust Bounding Box

Controls the size of the bounding box of the output image, in pixels.

When enabled, use the Crop controls to adjust the BBox manually.

When Override BBox is enabled, manually adjust the BBox by entering values in the x, y, r, and t controls.

You can also use the crop widget in the Viewer to adjust the BBox.

Click to run the selected detection method on all key frames for a calibration grid shot.

Grid detection consists of feature detection and feature linking. It can be run in one step, using Grids detection, or broken down into two steps to allow for manual corrections.

See the Grid Detection controls for more information on changing the detection parameters.

Sets the detection type executed by the Detect button:

• Features - resets the detection state and finds feature points in the input grid shot.

• Links - connects detected features to form a grid. This runs Features detection first if it has not been already been executed.

• Grids - runs the Features and Links detection steps without allowing you to apply manual corrections between the two.

Feature Detection

Sets the maximum number of detected features.

You can try increasing the Number of Features if the grid is not fully covered by feature points.

Sets the patch size for feature relocalization.

Try increasing the Patch Size if features are not consistently located on saddle points.

Sets the distribution of features in relation to each other.

This value should reflect the scale of a square element of the grid.

Sets the detection threshold at which features are rejected automatically.

You can increase the value to reject weaker features, such as points not on a grid.

Feature Linking

Sets the angle tolerance when linking neighboring features.

If you find there are too many missing links between adjacent features, try increase this value.

High values can introduce ambiguity in the linking process, so adjust the Angle Threshold to get the best coverage of the grid.

Sets the distance tolerance allowed when merging neighboring links.

You can increase the Distance Threshold to recover missing feature points after detection.

Sets the peak tolerance when detecting linking directions.

You can decrease the Peak Threshold to improve feature linking if the grid image does not contain a sufficient contrast.

Overlay

Selects what to display in the overlay:

• None - disables the overlay.

• Features - only displays detected feature points. Only features are editable in this mode. Deleting a feature does not delete any associated links.

• Links - only display the links between feature points. Only links are editable in this mode. Deleting a link does not delete the features it connects.

• All - displays both feature points and links. When this option is selected, both types can be edited at the same time.

These functions run prior to starting rendering in execute(). If they throw an exception, the render aborts.

These functions run prior to starting rendering of each individual frame. If they throw an exception, the render aborts.

These functions run after each frame is finished rendering. They are not called if the render aborts. If they throw an exception, the render aborts.

These functions run after rendering of all frames is finished. If they throw an error, the render aborts.