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Introduction
In the following articles, we will describe how to use Billboards with Tracked Camera compounds in Aximmetry.
The Billboard is necessary for applying shadows, reflections and occlusion of the talent in your virtual scene.
We assume that you have already set up your tracking system properly. If not, please check the article.
We also assume that you are already familiar with the basic Billboard concept and usage with virtual camera compounds. If not please check the Setting Up Billboards in Virtual Camera Compounds article.
This article discusses the placement of Billboards using Tracked Camera compounds.
We will start by describing a non-tracked Billboard setup so that later it will be easier to understand how tracked Billboards work.
To learn about setting up Shadows & Lights please refer to: Tracked Camera Billboards: Shadows and Lights
To learn about setting up Reflections please refer to: Tracked Camera Billboards: Reflections
To learn about setting up Occlusion please refer to: Tracked Camera Billboards: Occlusion
Tracked Camera Compounds
After adding a tracked cam compound to your project, you will find the INPUTS control board on the menu bar.
All settings we are going to discuss in this article are on the INPUTS control board.
Billboards in Tracked Camera Compounds
Tracked Camera compounds by default don't use Billboards. In order to use Billboards, you have to turn the Use Billboards switch ON.
It will make all the difference after setting up reflections and shadows.
Here, you can see a scene with Use Billboard turned OFF, so no reflections or shadows of the talent are visible.
Here, you can see a scene with Use Billboard turned ON. Reflections and shadows are now visible.
NOTE: These screenshots were created using the following stock studio scene: [Studio]:News Room\News Room - TrackedCam_3-Cam.xcomp
The Case of Multiple Billboards
Tracked Camera compounds by default can handle up to 3 Billboards per video input. These Billboards cannot duplicate the image of their respective video input. They merely allow for cropping different parts of the same fullscreen video input.
The Billboards are distinguished by a number and a letter, e.g. BILLBOARD 1A.
The number '1' indicates that this Billboard belongs to the first video input (INPUT 1). The letter 'A' indicates that this is the first Billboard of this video input.
For INPUT 1 you'll find the following Billboards: BILLBOARD 1A, BILLBOARD 1B, BILLBOARD 1C.
NOTE: The process of placing subsequent Billboards of the same video input is the same.
Reference Points
The placement of the Billboards can become confusing without the understanding and use of reference points.
Tracked Camera compounds work with a number of coordinate systems at a time:
- The virtual scene's coordinate system (Billboards being a part of the virtual scene are placed in this coordinate system)
- The inputs' tracking coordinate systems (multiple, in case subsequent tracking systems use different coordinate systems)
- The talent tracking's coordinate systems (optional).
What the Billboards' placement depends on, is the relative position of these coordinate systems to each other, and the transformation (position and rotation) of the objects (virtual scene, virtual cameras, Billboards) reported or set within their respective coordinate systems.
As Aximmetry allows for adjusting the origo of every coordinate system you can choose any of them to serve as a reference point for the placement of Billboards.
However, we recommend choosing INPUT 1's tracking coordinate system as the point of reference to place the Billboards. In the continuation of this document, examples are also based on this recommendation.
Use Billboards
To turn on Billboards in the scene, start by selecting the SCENE panel.
Then turn ON Use Billboards on the Pin Values panel.
NOTE: All other settings are specific for each scene. Other Pin settings might differ in your case.
At this point, the camera's image might disappear because the Billboard is placed at the origin of the scene. This is okay.
Placement of Billboard 1A
The process of the Billboards' placement is different for the first Billboard used in the production. We are going to cover every case starting with the first one, the placement of BILLBOARD 1A.
It is recommended to hold the camera still during the placement of the Billboards.
Lock To Camera
This enables the Billboard to be locked to the camera movement. The Billboard will stay parallel and keep distance to the tracked camera's plane, while the camera is moving.
NOTE: Turn this feature on when you want to place the Billboard inside the virtual scene.
NOTE: Turn this feature off when you don't want the Billboard to follow the tracked camera's movement.
NOTE: Lock to Camera overwrites the previously set Transformation values of the Billboard (see: Transformation).
Select BILLBOARD 1A.
Use the Lock To Camera feature to snap the Billboard in front of the camera.
At this point, the camera image will be visible again, but perhaps only partially.
Example of a partially visible camera image after turning on the Locked to Camera switch for the first time.
Settings Connected to this Feature
Locked Distance
This value sets the distance between the Billboard and the tracked camera in meters.
When setting this value, please consider the area the Talent is going to cover moving around during production. If the Talent walks closer to the camera than the distance specified here, the feet of the Talent will be cut off by the bottom of the Billboard. As the talent walks back, the shadows and reflections will become less accurate.
Locked Width
This value sets the width of the Billboard in meters.
When setting this value, please consider how far the talent is going to move to the left and right (parallel to the camera). If the talent walks 'off' the billboard, the image will be cut off by the edge of the Billboard.
Locked Height
This value sets the height of the Billboard in meters.
NOTE: it is recommended to keep a safe margin between the top border of the Billboard and the talent's head, to avoid accidentally cropping it during production, if the talent steps towards the camera.
Locked Offset X & Y
This value sets the offset of the center of the Billboard from the center of the video input in meters.
Locked Offset X sets a horizontal offset.
Locked Offest Y sets a vertical offset.
Locked Rotation
This value sets the rotation of the Billboard around its center in degrees.
This feature is useful in cases where e.g. your Talent is going to move in a certain direction during the show. You can set the Billboard parallel to that direction, keeping the reflection and shadows more accurate.
Transformation
This will only work if the Lock To Camera feature is turned OFF.
The transformation pin allows you to place the Billboard in the virtual scene.
This position will be fixed, even if the camera moves.
This position will be overwritten if the Locked to Camera is turned on.
Visibility
In order to properly position the billboard to suit our setup, you have to enable the Billboard's visibility.
Turn ON the lightbulb icon on the BILLBOARD 1A panel.
This is what the Billboard looks like after turning on visibility:
Turn OFF the Lock To Camera feature. If you keep this on, the Billboard will move and rotate when the camera moves, always pointing in the direction of the camera.
Now we move the billboard to the proper position, using the Transformation pin values.
We suggest placing the billboard a bit in front of the feet of the talent considering their movement towards and away from the camera. See example:
NOTE: If you place the Billboard too far from the talent, the reflections are not going to align with the talent's feet.
Another option is to use the Transformation Gizmo and Edit Scene Settings to move the Billboard. Either way, adjust its position carefully.
Placement of Billboard 1B & 1C
The use of BILLBOARD 1B and 1C are optional, therefore you don't necessarily have to turn them on and use them.
They are only needed when you e.g. have multiple talents in the fullscreen video input, and you want to separately crop different parts of the video input to display the talents on multiple Billboards.
BILLBOARD 1B and 1C are - by default - turned off.
BILLBOARD 1B and 1C are placed the same exact way as BILLBOARD 1A.
Turn Lock To Camera on for BILLBOARD 1B and 1C and set it up the same way we did for BILLBOARD 1A.
Then turn Lock To Camera off, and adjust the Transformation values of the selected Billboard to place them.
Placement of Billboard 2A & 3A
As the process of placing BILLBOARD 2A and BILLBOARD 3A are identical, for simplicity we'll proceed with BILLBOARD 2A in our example.
Switch Cameras
Head to the CAMERAS control board, then to the SELECT CAMERA control panel to select CAM2 for placing BILLBOARD 2A.
Align Tracking Coordinate System
Head back to the INPUTS control board.
On the MONITOR 2 control panel select Studio.
Select the ORIGIN 2 control panel.
Delta Cam Transf
The Delta Cam Transf parameter adds transformation relative to the tracking device's reported transformation.
Essentially, it moves the origo of INPUT 2's tracking coordinate system in the virtual space.
Adjust the Delta Cam Transf parameter to align the coordinate systems of INPUT 1 and INPUT 2's tracking devices.
NOTE: INPUT 1 and INPUT 2's tracking coordinate systems do not have to align perfectly. You can place INPUT 2's origin point at any arbitrary position that suits your production.
Place the Billboard
After the alignment is complete, place BILLBOARD 2A using the same method as for BILLBOARD 1A.
Placement of Billboard 2B, 2C & 3B, 3C
The process of placement of BILLBOARD 2B, 2C, and 3B, 3C are the same as it was for BILLBOARD 1B and 1C.
Billboard Tracking
If the talent will walk on the green screen during production, then we recommend tracking the talent's position with an object tracking system in order to match the position of the billboard to the position of the talent. This way all reflections and shadows will be automatically updated, even if the talent moves away from or toward the camera. We will call this a Tracked Billboard.
Object Tracking System
You can use different object-tracking systems to track the talent's position.
Set the Auto Position pin value to Tracking:
And under the Tracking Device, select the object tracking system you are using for the talent.
If you discover that the tracking is either late or early (there is a delay), you can adjust the delay at the Tracking Delay pin
Auto Pos Offset
This value sets an offset on the Billboard's tracking data alongside the camera-billboard axis.
Adjust it only if necessary.
NOTE: in case you use a different tracking system than the one used for camera tracking, check if their coordinate systems match. If they don't, then adjust the Talent Trk Transf parameter on the Studio control panel to compensate for their misalignment. More on this: Talent Trk
Optical Tracking
Set the AutoPosition pin value to Optical
This will track the position of the talent on the camera screen and will try to match the Billboard to this movement. This method is less reliable than using an object tracking system.
We recommend that the talent does not move too far from the original position and that the talent tries to move slowly.
