Motion control is the use of robotic camera equipment to create programmable, precise and repeatable camera moves. Many professional motion control service providers use custom rigs, some use commercially produced rigs such and the Milo. Lately, companies such as Bot & Dolly, The Marmalade and Mark Roberts Motion Control have adapted robotic arms normally used in manufacturing.

You can use motion control data as a seed or guide path for your virtual camera solve. The data from motion control rigs is the instructions, not a record of the actual movement. Therefore, the bumps and jitter present in the plate are not present in the data. This means that footage shot with a motion control system must still be tracked. Lightcraft Technology’s Previzion records the actual movement so it’s data has the potential to be more accurate than a rig’s.

Motion control data is primarily distributed as an ASCII table. Each row represents a frame and each column represents an axis of motion. The motion control system should be genlocked with the camera. After importing into a 3D package the motion control data will need to be conformed. The first step is synchronizing with the plate. This is usually done by using a bloop light recorded in the plate. The bloop frame should be noted in your delivered data. The path will then need to be oriented and scaled to match the virtual set. Some motion control systems have tools to assist with this. Some do not. The two most common motion control data formats are Kuper and Flair.

Motion control data can come from the following sources:

• Traditional motion control rig with a crane and dolly
• Motion control head
• Lightcraft Technology’s Previzion and Airtrack
• Lens Data System (LDS)

Pacific Motion Control: Kuper CG Resources
Pacific Motion Control: Technodolly CG Resources
FLAIR Motion Control System
Camera Control

Survey data can be used to increase the accuracy of camera solves, solve cameras that have zero parallax and solve different cameras in a matching scene layout. Survey data can be obtained by traditional surveying with a Total Station, scanning with LIDAR or shooting reference frames for photogrammetry.

Camera tracking software normally works by 2D tracking features in an image sequence. Using a photogrammetry algorithm it then estimates the 3D coordinates of these features. The camera is then solved based on the relationship of these coordinates. Using survey data is different. Instead of having the algorithm estimate the position of a 3D coordinate you simply tell the software where it is. If your survey data is accurate it will provide you with a better camera solve than estimation alone. Survey data and software estimation techniques can be combined.

Total Station
Survey data collected by a skilled surveyor with a Total Station is extremely accurate. However, this data is less convenient to correlate with production plates because it is a low density point cloud.

LIDAR
LIDAR scans provide excellent accuracy and a high density point cloud. In order to maximize usefulness in a visual effects pipeline the point cloud should be meshed.

Photogrammetry
Photogrammetry can be used to create a low or medium density point cloud of a set. This point cloud can be meshed. A large number of photographs are required and photogrammetry is generally less accurate than LIDAR or Total Stations.

Reference Frames
Reference frames are used to give the camera solving algorithm more parallax. Reference frames are photographs of the set taken from angles different from the plate camera. These photos must have overlapping coverage of the features being 2D tracked. They can include DSLR photos, videos and witness cameras. Reference images can also be taken of specific objects or props to assist in object tracking.

1. original plate
2. remove lens distortion (undistort plate)*
3. camera tracking/matchmove
4. cg pipeline (undistorted)
5. render cg with overscan (undistorted)**
6. distort cg render
7. composite over original plate

* Step 2 assumes a lens distortion grid was photographed or lens mapping data was acquired. Step 2 is often part of step 3. Camera tracking software can calculate lens distortion from most plates.

** Step 5 is required when undistorting barrel distortion. If overscan is not rendered the edges of the frame will be cropped when distortion is applied.

Wikipedia: Distortion (Optics)
SynthEyes Lens Distortion Tutorials
SynthEyes Lens Distortion White Paper
SynthEyes Lens Distortion and Anamorphic Padding White Paper
3D Equalizer: Lens Distortion Model
3D Equalizer: Lens Distortion in 3DE4
3DEqualizer4 R4 [advanced] – Lens Distortion Pipeline / Export Distortion Data to Nuke

There are two workflows for handling plates with rolling shutter artifacts:

• The first workflow is to remove the artifacts from the shot. In this scenario the final composite uses the corrected plate.
• The second workflow is to add rolling shutter to the CG to match the plate. In this scenario the final composite uses the original uncorrected plate.

WORKFLOW 1

1. original plate
2. remove rolling shutter
3. remove lens distortion (undistort plate)*
4. camera tracking/matchmove
5. cg pipeline (undistorted)
6. render cg with overscan (undistorted)**
7. distort cg render
8. composite over unrolled plate

* Step 3 assumes a lens distortion grid was photographed or lens mapping data was acquired. Step 3 is often part of step 4. Camera tracking software can calculate lens distortion from most plates.

** Step 6 is required when undistorting barrel distortion. If overscan is not rendered the edges of the frame will be cropped when distortion is applied.

WORKFLOW 2

1. original plate
2. remove rolling shutter
3. remove lens distortion (undistort plate)*
4. camera tracking/matchmove
5. cg pipeline (undistorted)
6. render cg with overscan (undistorted)**
7. distort cg render
8. add rolling shutter
9. composite over original plate

* Step 3 assumes a lens distortion grid was photographed or lens mapping data was acquired. Step 3 is often part of step 4. Camera tracking software can calculate lens distortion from most plates.

** Step 6 is required when undistorting barrel distortion. If overscan is not rendered the edges of the frame will be cropped when distortion is applied.

Wikipedia: Rolling Shutter
RED – Learn: Global and Rolling Shutters
RED – Learn: Temporal Aliasing with Cinema
RED – RED MOTION
Tessive: Time Filter
Tessive: Time Filter Technical Explanation
DIY Photography: Everything You Ever Wanted To Know About Rolling Shutter
Rolling Shutter on CMOS
Adobe After Effects: Rolling Shutter Repair
Adobe Premiere Pro: Rolling Shutter Repair
SynthEyes Rolling Shutter Tutorials
3DEqualizer4 [advanced] – Rolling Shutter
3D Equalizer: Rolling Shutter Correction in 3DE4
The Foundry: Rolling Shutter (Defunct)