Virtual Production and
Finally, visually complex productions can actually see the entire shot during production, instead of staring at a wall of green. When everyone sees the same image, decisions are rapid and stage operations efficient.
On Set Vis
Previzion provides the following on stage benefits:
- Know that you have the shot before you wrap.
- Make the movie once instead of three times, using Previzion’s clean data workflow to go from previsualization to production to post production.
- Remove surprises from the visual effects process.
- Tune on set lighting with the composited preview image, to avoid expensive re-lighting in post.
- Catch and diagnose keying problems easily, before paying for them in post.
- Catch set extension or character mismatch problems instantly.
- See the entire shot at once.
- Retain artistic control with DP and director.
- Unified Camera Tracking
- Accurate Lens Calibration
- Stereoscopic Integration
- External Animation Integration
- Portable and Silent Operation
- Complete Scene Loading
Unified Camera Tracking Architecture
There are nearly as many different tracking technologies as there are shots in which they are used. Previzion provides the best of both worlds — the ability to adapt to multiple different camera tracking technologies, handled with a unified interface that makes setup and registration straightforward.
From optical/inertial, to encoded systems, to motion capture stages, to GPS/IMU outdoor tracking, Previzion can handle nearly any form of tracking device.
Compatible With All Digital Cinema Cameras
Previzion has been tested and verified with nearly every digital cinema camera in production:
- Red One/Epic
- Arriflex D20/D21/Alexa
- Sony F23/F35/EX3
- Panavision Genesis
- Film cameras (when fitted with HD video taps)
Match Live Action and Survey Data. Instantly.
Modern VFX shots require extremely accurate matching of the virtual and live action worlds. Previzion provides tools to rapidly match the tracking coordinate systems into existing LIDAR and survey data, with real time, through the lens alignment.
Image: LIDAR mesh overlaid onto live action image with Previzion lens/tracking data. Image courtesy of Evergreen Films
Optical/Inertial. For Ultimate Tracking Flexibility.
The fusion of the Intersense IS1200 optical tracking camera and the Lightcraft Airtrack electronic gyro provides tracking for the broadest range of shots. From handheld and Steadicam, to dolly, jib, and Technocrane shots, this can handle nearly everything.
Using targets mounted overhead in the stage truss, a standard stage can be converted into a real time capable smart stage in a single day.
Connect to Industry-Standard Encoded Cranes, Jibs, and Sliders
For high precision tracking outdoors, or where optical targets are difficult to mount, Previzion provides a direct connection to the Kuper/General Lift encoded cranes. Previzion handles all the joint transformations, boom extension sag, and provides a new method of registering encoded cranes into a virtual environment — instantly.
GPS/IMU Exterior Tracking
For the ultimate in unconstrained exterior tracking, Previzion supports fused GPS + IMU (gyro) tracking. Connect to industry standard units, and Previzion matches the GPS coordinate system into local LIDAR and survey scans, all in real time.
Handheld, Steadicam, crane . . even dirigible type shots can be tracked with this technology.
Fiber Optic Data/Video Integration
For wide-ranging outdoor shoots, an optional set of cables enables Previzion video and tracking data to be transmitted over the Telecast Copperhead 3400 fiber optic camera connection. This enables very long cable runs (up to a kilometer) without compromising video or data signal integrity.
Note: Integration with the Telecast Copperhead 3400 is not possible with the Intersense IS1200, as the IS1200 uses the RTS pin for its serial protocol. This is not supported by the Copperhead 3400. However, the serial data from General Lift encoded cranes, and lens data (besides Fujinon, which also uses the RTS pin) can be sent over a fiber optic link.
Low Latency Operator Preview
Previzion provides two separate real time HDSDI outputs.
The normal ‘archival’ feed is a clean image, contains embedded audio and timecode, and has about a 5 frame delay from the camera to the output.
The new ‘operator’ feed is a very low latency feed (1.5-2 frames). It does not have embedded audio or timecode, and has some visual shearing artifacts due to the direct transfer from the screen. However, for situations where an operator has to follow a fast-moving virtual character or object, the immediacy of response is invaluable.
Accurate Lens Calibration
The core of live action image is the camera lens, and the key element in matching CG elements into live action footage is accurate and complete measurement and recreation of all critical lens parameters.
Previzion’s unique, patent-pending lens calibration system brings all of these attributes together into a straightforward, repeatable, production-friendly interface.
Standard Follow Focus Controls
Previzion’s lens calibration system is designed to interface with the remote follow focus and zoom controls that you already know and use.
Lightcraft has already engineered the cables and serial interface code to multiple lens control systems:
Preston Cinema FIZ
C Motion cvolution camin 2M/4M/8M
RT Motion lens controllers (legacy support only)
Canon lenses with virtual ports
Fujinon lenses with serial ports
Cooke /i compatible lenses
Standard Production Lenses
Previzion’s lens calibration system can measure and map nearly any standard production lens — Cooke, Angenieux, Zeiss, etc.
By moving the lens through its complete range of possible motions, Previzion builds an accurate lookup table that contains the true lens parameters wherever the lens is moved.
Complete Lens Parameter Measurement
A modern zoom lens has an extraordinary range of adjustment, which requires a corresponding range of calibration. To completely simulate a zoom lens requires accurate measurement of the true focal length, true focus distance, entry pupil location, and optical distortion. Absent any of these parameters, the CG and live action simply won’t match, no matter how much you adjust.
Previzion’s patent-pending lens calibration system uses machine vision techniques to completely map a lens. The above example shows just how much the entry pupil/nodal point of a modern lens moves as the lens is zoomed in and out. The entry pupil location is where the CG virtual camera must be placed for an accurate scene match. After seeing this, it becomes clear why zoom lenses have been previously considered difficult to track.
The best lens calibration system in the world is useless if it can’t go where the cameras are. For VFX production, that means a moving target.
Previzion’s lens calibration software is built into the system, and the calibration target can easily be transported on location. This is critical for fast-m0ving productions where the camera and lens may only become available for a matter of hours, and calibration must be done in a hallway or in the parking lot outside the stage.
Lens distortion is one of the areas that cause the most confusion in visual effects. With wide angle lenses, it causes buildings to bow outward near the edges of the frame.
To accurately match CG and live action, the lens distortion must be both accurately measured and rendered — otherwise, the environments simply will not line up, no matter how much fiddling with alignment is attempted.
Previzion’s lens calibration system and matched real time renderer correctly match the CG image to the live action image. In addition, distortion is captured and recorded on a frame-accurate basis for use in post production pipelines.
Stereoscopic 3D VFX work is very dependent on optical accuracy — you simply can’t move things around until it ‘looks right’. Since Previzion was built from the ground up with accuracy as its goal, stereo VFX tracking is a natural fit.
Previzion supports the following rig metadata protocols:
Other protocols can be rapidly added upon request.
Most production stereoscopic camera rigs will output real time IO and convergence data. However, the data is based on a measurement where the front rig pivots are, which does not necessarily match up with where the entry pupils of the lenses are. The entry pupil location provides the true IO/convergence as opposed to the rig’s IO/convergence.
Previzion’s stereo rig connection reads the rig’s real time data, and correctly calculates the true IO and convergence based on the rig data, the rig geometry, the mount points of the camera sensors, and the lens entry pupil location measured from the individual lens calibrations.
In this way, the CG elements are correctly located in the same stereo space as the live action elements, which is critical for stereo VFX matching.
Real Time IO and Convergence Data
For many stereo moves, the IO and convergence must be moved during the shot for the best stereo effect. Of course, the CG elements in the scene must also follow this movement.
Previzion reads real time stereo metadata from motorized stereoscopic rigs, and correctly renders the left or right eye CG elements into the matching live action frame — in real time, while the rig is being moved.
In addition, the resulting stereo metadata is recorded into the take file for frame-accurate recreation of the stereo move in post production.
Dual System Stereo Preview [Under Development]
For real time stereoscopic preview of matched and synchronized live action and CG elements, connect two Previzion systems together. Each system renders and composites one eye. The dominant eye system handles all tracking data, and remotely drives the rendering of the secondary system based on the lens information and stereo metadata.
This enables accurate preview of high frame rate 48fps and 60 fps stereo shows, which are very demanding to render.
External Animation Integration
Previzion provides complete, scalable, network based animation input and output for complete control of the scene. Use keyframed animation, pre-recorded motion capture data, or even live motion capture data to drive characters and objects in camera.
With the Prelink MotionBuilder plugin, Previzion can interface to any animated character or object in Motionbuilder, and work with nearly any motion capture suit or volume in production.
Prelink transmits only the skeleton data over the network to identically named skeleton nodes in the Previzion scene. Previzion then renders the animated characters or objects as part of its scene, with correct motion blur, depth of field, reflections, and lens optics for a precise, frame-synchronized match.
Animation Timecode Capture
Previzion reads and records the current frame on the timeline from Motionbuilder, so that the exact frame of animation in question can be matched to the exact frame of live action video, vastly simplifying post production work and providing an accurate recreation of how the live action and characters were interacting on set that day.
Live Camera Data Output
Previzion can transmit a real time camera data output over the network, enabling external rendering engines to use the live data.
The real time data packet contains all of the parameters used by Previzion for rendering, including:
Camera position and orientation
Lens field of view, focus distance, entry pupil calculation, and distortion
Timecode of current frame
Reading the live Previzion data output is already built into the Prelink/Precam software plugin set, enabling live Previzion data to drive the Motionbuilder camera in real time.
Object and Visibility Control
Previzion enables remote object visibility and position control. As shown above, when the Motionbuilder scene is modified, or objects hidden and shown, the corresponding objects in Previzion are also moved or hidden.
Standard Network Animation Protocol
Previzion’s network animation system is based on the Collada XML standard. In this way, multiple external tracking or motion capture devices can be easily integrated with Previzion over the network.
By allowing multiple devices to sync with Previzion over a network, Previzion enables the most time-saving device available on a stage: division of labor.
The Previzion operator can concentrate on the keying, tracking, rendering, and take recording components, while the Motionbuilder operator can concentrate on the myriad adjustments to character and scene that are usually requested on a take by take basis by the director.
Portable and Silent Operation
Previzion can be ordered as a rack mounted studio unit, or as a highly portable unit with a suitcase form factor that fits into carry-on airline space (pictured on right).
Both studio and portable models use identical processing hardware and are heavily silenced, and can operate in typical soundstage conditions without additional tenting or silencing required.
Complete Scene Loading
Previzion’s sophisticated scene loaders bring in complete 3D models, including geometry, textures, lighting, materials, CgFx shaders, and UV maps. This lets a production clearly see how the various pieces of a visual effects shot will come together.
Previzion’s FBX loader enables direct import of scenes from Motionbuilder or other packages that can export FBX files. This enables a very straightforward data workflow for existing Motionbuilder environments.
Collada Scenes with References [Q3 2011]
Collada is a powerful, flexible standard for saving 3D scene data. Its ASCII text/XML core makes large scene debugging and asset management simple, without the complications of large binary files.
Previzion’s Collada importer will support a full range of Collada data, including geometry, textures, materials, and CgFx shaders.
In addition, Collada supports the use of asset references, so that scenes can be loaded with a lightweight master scene that contains the positions of a large number of scene objects, which are then loaded from individual object asset Collada files.
In this way, the on set scene asset management can closely mirror the traditional post production pipeline, enabling seamless transfer of set data into post.
Matched Maya Preview
By using CgFx shaders, look development can be done in the Maya environment, and render identically in the Previzion environment.
CgFx shaders work directly at the GPU level, removing the traditional problems of material translation when going from one rendering system to the next.