2.11 LED Screen Calibration
LED Screens are not calibrated in the same way that Projectors are. There are many differences between the instructions for LED Screen calibration and those listed in Section 2.3 Manual 2D Keystone Calibration and Section 2.4 Manual 3D Calibration.
The main differences between these approaches are the following:
Display Type
LED Screens use the LED Processor Display type instead of Projectors. They are the only other Display type that can be linked to a video output.
Calibration Tools Interface
If an LED Processor Display is selected in the Calibration Tools list, the Calibration Tools interface will change and offer a new set of options that are appropriate for LED Screens.
Calibration Technique
LED Processor Displays use quads (cells featuring a quadrilateral shape) to segment, resize and position video content in a virtual 2D space. The resulting visual composition is then outputted to the real-world LED Processors connected to the LED walls. This approach facilitates content mapping for these devices.
2.11.1 Add an LED Processor
The first step is to add an LED Processor Display in the 3D Scene module. If the project you are working on features many real-world LED Processors, you will have to add an LED Processor Display for each of them.
Make sure the 3D Scene module is open (by pressing [Alt+C] or by selecting {System > 3D Scene} from the Main menu).
Select {Primitive > Display > LED Processor} from the Primitive dropdown menu.
The LED Processor will appear at the bottom of the Scene Primitives list.
The LED Processor Display is not represented in the 3D Scene Preview.
2.11.2 Add a Primitive
While LED Screens are not Projection Surfaces, they still need to be linked to a 3D object. The shape of the 3D object should match the shape of the real-world LED Screen. The selected 3D object is often a plane because LED Screens tend to have a rectangular format.
To add a default 3D object to the 3D Scene, select {Primitive > Default Objects > any of the objects listed here} in the Primitive dropdown menu
The 3D object will appear in the Scene Primitives list, and a visual representation of it will appear at the origin (0,0,0) of the 3D Scene Preview.
Many ready-to-use 3D objects are available in TACHYON. Referred to as Default Objects, they simplify the construction of the virtual representation of your real-world stage space. Default Objects can be selected from the Primitive dropdown menu {Primitive > Default Objects}.
2.11.3 Declaring a LED Surface
TACHYON’s default behavior is to consider any 3D object added in the 3D Scene module as a Projection Screen.
Tachyon needs to be told that the Plane is a LED Surface:
Select the 3D object by clicking on its entry in the Scene Primitives list.
Press [P] on the keyboard or select {Options Panels > Properties} from the 3D Scene module’s menu to open the Properties Panel.
Click on the first dropdown menu in the {Display Options} section of the Properties Panel to change the default option from {Projection Surface} to {LED Surface}.
2.11.4 Scale, Move, Rotate the 3D Object
It is possible to modify the shape of the 3D object in order to match the ratio of the real-world LED Display it represents. You can also position and rotate the 3D object in space to match the position and orientation of the real-world LED Display. Since the calibration process for LED Displays relies strictly on 2D texture mapping (LED Displays are not Projection Surfaces), scaling, positioning and orienting are not crucial. However, doing so is considered a best practice and will give you access to a realistic pre-visualization of the project.
Project pre-visualization is one of TACHYON’s key features. VYV’s software can create full 3D simulations of the real-world stage space.
Applying the Transformations
A 3D object’s size, position or orientation in the 3D Scene can be modified using the Transformations Panel or Transformation Manipulators.
Transformations Panel
The Transformations Panel contains multiple sliders that allow the modification of the Scale, Translate and Rotate parameters for each axis (X, Y and Z) for any object previously created in the 3D Scene module.
Select the object you want to alter by clicking on its entry in the Scene Primitives list.
To open the Transformations Panel, press [T] on the keyboard or select {Options Panels > Transformation} in the 3D Scene’s main menu.
To change the geometric coordinates of an object, adjust the value of the sliders. You can adjust the value of a slider by manipulating it with a [Click+Drag], or you can [Double-click] on it to open a text field where you can enter a desired numeric value.
The effects of these transformations can be seen in the 3D Scene Preview. The visual representation of the selected object will be modified as well.
Slider values differ depending on the parameters they represent. The Scale sliders are not dimension sliders; they act as scaling coefficients applied to the object’s original size. For example, if the scale value of a cube featuring edges of 2 meters is changed from 1 to 4 on all three axes, the cube will now have edges of 8 meters. The Translate sliders express a value in meters. The Rotate sliders express values in angles. And the Rotate Axis sliders are used to apply a rotation expressed in an angle that corresponds to specific vectors. For example, an angle is set with the first slider while the three other sliders represent vector values for each axis that will determine how the rotation will be applied to each.
Transformation Manipulators
The Transformation Manipulators facilitate direct modification of a 3D object’s parameters —Scale, Translate, Rotate — by manipulating your mouse in the 3D Scene Preview.
Enable the desired Transformations Manipulator using the following methods:
Scale Manipulator: Press [X] on the keyboard or click on the Scale button located in the top-right corner of the 3D Scene window.
Translate Manipulator: Press [V] on the keyboard or click on the Translate button located in the top-right corner of the 3D Scene window.
Rotate Manipulator: Press [C] on the keyboard or click on the Rotate button located in the top-right corner of the 3D Scene window.
The Transformation Manipulators will appear when a 3D object is selected.
TACHYON’s Manipulators feature a standard color-scheme for its 3D coordinate system: X is red, Y is green and Z is blue.
[Click+Drag] the handle of the axis parameter you want to modify (X, Y or Z). The handle will become yellow when selected.
The Scale and Translate Manipulators feature a yellow dot at the intersection of their axes. [Click+Drag] the yellow dot to simultaneously apply transformations to all axes.
Enabling a Manipulator will disable camera movements in the 3D Scene Preview. To switch back to camera control, press [S] on the keyboard or click the Camera button located at the top-right corner of the 3D Scene.
If you want to control the camera while a Manipulator is enabled, press and hold [S] on the keyboard. This will allow you to manipulate the camera. To switch back to Manipulator control, release the [S] key.
2.11.5 Map the 3D Object to the LED Processor
In order to calibrate the LED Display you will need to establish a link between the 3D object acting as a Screen and the LED Processor. The 3D object must be added to the LED Processor’s Objects Reference list.
There is no Visibility list for LED Processors. Once added to the Objects Reference list, the 3D object is automatically “made visible” because LED Displays are not Projection Surfaces.
Select the 3D Scene module’s Calibration mode by pressing [2] or by clicking on the [Calibration] button located at the top-right corner of the 3D Scene window.
Once the Calibration mode is enabled, the 3D Scene Preview will turn red and the Calibration Toolswill open in the lower right part of the 3D Scene window.
Select the LED Display you want to calibrate by clicking on its entry in the Calibration Tools list. (If you haven’t renamed the LED Display, it will be listed as “LED Processor.”)
Make sure the Display Grid is enabled. The Display Grid will facilitate further operations by showing how the image texture is distributed on the Display.
Press [D] or click on the gear icon button to access the 3D Scene module’s Settings menu and click on the [Display Grid] toggle if the Display Grid isn’t already activated.
Add the 3D object to the Objects Reference list.
In the LED Options section (right of the Calibration Tools), select the 3D object from the {Model Selection} dropdown menu.
Click on the [Map] button to add the 3D object as a Reference Object.
Multiple 3D objects can be linked to the same LED Processor by repeating the previous steps. Inversely, the same 3D objects can be linked to multiple LED Processors.
2.11.6 Create Quads and Resample Texture
The LED Processor Display uses Quads to resample video texture and assign it to segments of the real-world LED Display. In order to calibrate an LED Display, one or many Quads will have to be created, modified and distributed while respecting the ratio of the real-world LED Display.
Create a New Quad
Click on the [+] button located at the middle of the LED Options section of the Primitive Preset Panel in the Calibration Tools Window.
An entry named “Quad1” should appear in the Quad list located below the [+] button. Additional Quads can be created and will populate this list.
Modifying the Quad’s Size, Shape and Texture Mapping
By default, a newly created Quad has the same size as the full resolution of the output it is linked to. A new Quad is “full screen,” however, its size, shape and texture mapping can be modified to fit your needs. This can be done through two different methods:
Using the LED Options Widgets
The right side of the Calibration Toolscontains many widgets such as dropdown menus, toggles and sliders that you can use to modify the Quad’s parameters. Below you will find brief descriptions of these options (listed from top to bottom, as in the UI):
Primitive
This dropdown menu assigns a specific 3D object to the selected Quad. This feature is useful in cases where multiple Screens (represented by 3D objects) are linked to the same LED Processor.
Orientation
This dropdown menu rotates the texture inside the Quad by increments of 90 degrees.
[Flip]
This toggle enables (or cancels) the geometrical reflection of the texture along its horizontal axis.
[Flop]
This toggle enables (or cancels) the geometrical reflection of the texture along its vertical axis.
Texture
These 2D sliders will change the size and position of the texture sampled by the currently selected Quad.
Output
These 2D sliders will change the size and position of the Quad in the video output.
Setting Texture Resolution
The texture resolution has to be set through the Screen’s texture properties.
Select the Screen by clicking on its entry in the Scene Primitives list. (The Screen is a 3D object you previously added to the list.)
Press [P] or select {Options Panels > Properties} from the 3D Scene menu to open the Properties Panel.
Set the desired horizontal and vertical resolutions using the width and height sliders located underneath the Texture section of the panel. (The sliders can be manipulated with the mouse or you can [Double-click] on them to open text fields where you can directly input numerical values.)
Setting Output Resolution
You will need to set the LED Processor output resolution so it matches the resolution of its Video Output Port (the graphic card’s physical output).
The resolution of the Video Output Port can be found in the Settings module.
Press [Alt+S] or select {System > Settings} from the Main menu to open the Settings module.
Select the Server and the Output you want to monitor by clicking on the appropriate entries in the TACHYON Selection list and the Outputs list. The resolution of the Video Output Port should be indicated in a dropdown menu located in the Output Resolution window section.
The resolution of the LED Processor output can be set in the 3D Scene module.
Press [Alt+C] or select {System > 3D Settings} from the Main menu to open again to the 3D Scene module.
Select the LED Processor from the Calibration Tools display list by clicking on its entry.
The height and width sliders located in the LED Options window section of the Calibration Tools can be used to set the LED Processor output resolution.
Enter the horizontal resolution value of the Video Output Port using the width slider by either manipulating it directly with the mouse or by [Double-clicking] in it to open a text field where you can enter a numerical value.
Enter the vertical resolution value of the Video Output Port using the width slider by either manipulating it directly with the mouse or by [Double-clicking] in it to open a text field where you can enter a numerical value.
Offset the Output
The width and height offset sliders can be used to offset the entire output.
The LED Processor’s output resolution has to match the resolution of the Video Output Port found in the Settings module.
Direct Quad Manipulations in Calibration Tools Preview
You can manually resize and position the Quad in the video output by using your mouse. To modify the texture’s parameters follow these steps:
Select the Quad you want to resize or position by clicking on its corresponding entry in the Quads list in the LED Options window section or [Double-click] on its representation in the Calibration ToolsPreview.
[Click+Drag] inside the Quad to reposition it in the video output.
[Click+Drag] the corners of the Quad to resize it.
Holding the [Shift] key while performing the [Click+Drag] actions on the Quad will increase the mouse’s precision.
You will usually input exact values in the Texture and Output 2D sliders located in the LED Options widget rather than perform direct manipulations on the Quads since LED Displays require pixel-perfect precision. However, you can use the manual method to rapidly get a rough preview of the final LED mapping.
The coordinates of the texture’s top-left corner are 0,0 (which is standard in the LED industry).
LED Processor View Modes
You can switch between two different view modes in the Calibration Tools Preview when an LED Processor is selected.
Select either the {Texture} or the {Output} option from the View Mode dropdown menu located in the LED Options window section of the Calibration Tools.
Output View Mode
Shows what is sent to the Video Output Port (the graphic card’s physical output).
Texture View Mode
Shows the section of the Screen’s texture that is resampled by the selected Quad.
2.11.7 Assign the LED Processor to an Output
In order to output video from the graphic card connector to the real-life LED Display, you will have to link the LED Processor to one of the Virtual Video Outputs in the Settings module.
Press [Alt+S] or select {System>Settings} to open the Settings module.
Click on the entry corresponding to the Server you want to calibrate from the TACHYON Selection List.
Once the Server is selected, make sure you identify the Virtual Video Output corresponding to the Video Output Port connected to the real-world LED Display. If the Virtual Video Output is missing, click on the [+] button to create a new one.
Select the LED Processor you want to assign to the Virtual Video Output by using the dropdown menu located to its right.
Last updated
