2. 3D Scene
The 3D Scene module is used for integrating video outputs (such as projectors), video inputs (such as cameras), screen surfaces and decorative elements in a virtual representation of the real-world stage space. It is through manipulations of this virtual stage space (the 3D Scene) that operations such as projector calibration, primitives manipulation and blending will be made possible.
Tasks and operations described in this section of the manual mainly have to do with the binding between the real-world stage space and the virtual stage space as it is represented in TACHYON. Naturally, if you want to see actual results in the real world, Displays (such as video projectors or monitors) must be connected to the Video Output Ports, and you have to declare all of your project’s Virtual Video Outputs in the Settings module (see Section 1.6 Virtual Video Outputs Creation in Chapter 2 Setting Up a Show).
Throughout this section of TACHYON’s technical documents the following terms are regularly used:
Displays are any kind of device used for displaying video signals, such as video projectors, video monitors, LED walls, etc.
Signal transmission refers to the act of sending a video signal point-to-point from a Video Output Port (a graphic card’s physical output) to a device used for display, such as a video projector or monitor. Signal transmission is usually accomplished through cable distribution (fiber, HD-SDI, Ethernet, etc.).
Video Output Ports are the physical connectors attached to the graphic cards that are installed in the servers used to output video signal.
TACHYON uses Virtual Video Outputs as a way to represent the Video Output Ports. Virtual Video Outputs have to be declared in the Outputs list located in the TACHYON tab of the Settings module window (see Section 1.6 Virtual Video Outputs Creation in Chapter 2 Setting Up a Show).
Virtual Displays are the virtual counterparts of the tangible, real-world displays described in this lexicon. Some types of Virtual Displays, such as Projectors, can be automatically created when Virtual Video Outputs are first declared.
TACHYON’s structure is based on real and virtual screens. All screens used as displays in the physical world have a virtual counterpart in the 3D Scene module, which acts as a simulation of the stage (or exhibition) space. Each real-world screen will have to be represented by a virtual one, which in turn will be linked to one or more video outputs. In the 3D Scene module, Screens act as a virtual representation of the Projection Surfaces. They are also represented in the Timeline module, where you can assign layers of media clips to them.
The term “video content” refers to the still images and video files that are imported into TACHYON, mapped as a texture onto Screens, and eventually played back using the Timeline module.
Calibration designates a process through which geometric coordinates are established between elements in the virtual scene and their real-world counterparts. By aligning the geometric features shared by a real screen surface and its model, TACHYON can reconstruct the position and orientation of displays as a means of mapping video content onto physical objects and other structural elements of the real-world stage. Many processes taking place during calibration are handled automatically by TACHYON. For example, edge blending between video outputs can be calculated dynamically with minimal user intervention (pressing a button once). The system also automatically differentiates between cases where 2D or 3D transformations are applied, based on the geometric characteristics of the screen’s surface.
Blending designates a process through which the projected images of multiple projectors are altered and seamlessly blend into one another, creating an uninterrupted surface (see Section 2.8 Blending in Chapter 4 Programming a Show).