Nuke W10 – 3D tracking

3D classic vs 3D beta

• Classic still incorporate FBX or Alembic. Nodes are green.
• Beta adapt to USD workflow. Nodes are red.
• You can’t mix nodes from the classic 3D system and the new 3D system. There are a few notable exceptions to this rule, like CameraTracker and DepthGenerator. Classic 3D system nodes are green by default and new 3D nodes are red.
• The red new version is still quite unstable, we should use the classic version for now.

3D navigation

Scene Node: is used to manage and assemble 3D geometry, lights, and cameras. It acts as a container/collector for all your 3D elements. When you connect multiple 3D objects to a Scene node, you can manipulate them as a single unit, which simplifies the process of working with complex 3D composites.

Camera Node: In Nuke, the Camera node is a virtual representation of a real or imaginary camera. It’s used in 3D compositing to define the perspective and projection of a scene. You can adjust parameters like focal length, aperture, and field of view. This node is crucial for match-moving and integrating 3D elements into 2D footage, as it helps in replicating the original camera movements and settings.

ScanlineRender Node: This is a rendering node used to render 3D geometry in a scene. It works by converting the 3D data into a 2D image, using the settings from the Camera node

Lens Distortion

Resources:
Working with Lens Distortion: https://learn.foundry.com/nuke/content/comp_environment/lens_distortion/adding_removing_lens_distortion.html

Lens distortion refers to the way a camera lens can warp or distort the image it captures. This isn’t necessarily a flaw; in fact, it’s often a characteristic of the lens design. There are mainly two types of lens distortions: barrel distortion and pincushion distortion.

1. Barrel Distortion: This occurs mostly in wide-angle lenses. It makes the image appear bulged outwards from the center. Think of how a fisheye lens makes things look curved and expansive. It’s often used for artistic effect or to create a sense of immersion.
2. Pincushion Distortion: The opposite of barrel distortion, this happens more in telephoto lenses. The image appears pinched at the center, making the edges seem to bow inwards. It’s less common in everyday photography and filmmaking.

LensDistortion Node: This node is used for correcting or applying lens distortion. It allows you to analyze an image for any barrel or pincushion distortion and correct it, or you can intentionally add distortion to match CG elements with live-action footage

It’s important to use LensDistortion (Undistort) before doing many match-move or tracking in order to work with correct information then use LensDistortion (Redistort) afterward to return the plate to correct format.

LensDistortion > Analysis > Detect or Draw (Straight Lines) > Solve
Draw horizontal and vertical lines to help giving as much information to Undistort as possible, especially around the edges. Then click Solve.

LensDistortion (StMap) introduce “forward” and “backward” as an option to view and is lighter to use & faster to view.

1. Denoise your plate then treat it (color grade etc)
2. Roto out area that you want to avoid tracking (things that move/not static, be mindful of reflective objects)

CameraTracker analyses the motion in a 2D footage and extrapolates this movement into a 3D camera path. It tracks various points in the footage (usually high-contrast or distinctive features) across frames to determine how the camera was moving when the footage was shot.

Source: sequence or still

Autotrack: to improve tracking

Click on error-max. click on graph and press F

reduce Max error to 6, click delete unresolved and delete rejected

Usually solved error is anywhere around 1 or below is good

To check tracking:

• Select some point > Create > Cube/Plane
• Plug the object Card into Scene > move it to match the ground plane