> For the complete documentation index, see [llms.txt](https://stage-precision.gitbook.io/grid/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://stage-precision.gitbook.io/grid/camera-calibration/before-you-start/calibration-references/calibration-screens.md). # Calibration Screens Calibration Screens are one of the standard reference types used for camera calibration in Grid Studio. A Calibration Screen represents a known physical reference surface that is visible in the camera image and can be used by the calibration tools. This can be an LED wall, monitor, TV, printed board, or another precisely measured flat calibration target. Grid Studio can generate calibration images for these surfaces. These images are displayed or placed on the physical surface and are used by the calibration tools as visual references. The important requirement is that the size of the physical reference surface and the displayed or printed calibration image is known and matches the configuration in Grid Studio. *** ## Why Calibration Screens Are Needed Calibration tools need known visual references to calculate the relationship between the live camera image and the virtual 3D scene. When the camera sees a Calibration Screen, Grid Studio can compare the visible calibration pattern in the camera image with the known size and layout of the corresponding Screen object in the project. This allows Grid Studio to solve or update different parts of the setup, depending on the selected tool: * lens behavior * tracking alignment * camera placement * screen placement * screen orientation * screen shape or geometry Without known reference surfaces, the calibration tool cannot reliably determine how the camera image relates to the physical stage and the virtual scene. {% hint style="info" %} If you cannot use a physical Reference Surface with a Calibration Image, use **Manual Markers / Measurement Points** instead. {% endhint %} *** ## Supported Reference Surfaces Calibration Screens can be used with different types of physical reference surfaces. Common examples are: * LED walls * monitors * TVs * printed calibration boards * precisely measured flat calibration targets The surface does not have to be an LED wall or a display. A printed board can also be used, as long as the physical size is known and the calibration image is printed at the correct scale. *** ## Physical Size and Accuracy The physical size of the reference surface is critical. Grid Studio needs to know how large the Calibration Screen is in the real world. If the configured size in Grid Studio does not match the physical surface, the calibration result will be inaccurate. For digital displays, the configured screen size and resolution must match the real display setup. For printed boards, the physical print size must match the dimensions configured in Grid Studio. Small measurement errors can lead to visible calibration errors later, especially in workflows where the Calibration Screen is used to solve tracking alignment, lens behavior, or screen placement. *** ## Digital Screens For digital screens such as LED walls, monitors, TVs, or media-server outputs, the calibration image must be displayed pixel-correctly. Pixel-correct means that the image is shown without unwanted scaling, cropping, stretching, overscan, or additional image processing. Before starting the calibration, check that: * the calibration image matches the configured screen resolution * the image is not scaled by the operating system, media server, LED processor, or display device * the complete image is visible * no part of the image is cropped * the aspect ratio is correct * the physical screen size matches the configured dimensions in Grid Studio If the calibration image is scaled or distorted, the detected pattern positions will no longer match the expected positions in Grid Studio. *** ## Printed Boards Calibration images can also be printed and mounted on a physical board. This is useful when no LED wall or monitor is available, or when a portable calibration target is needed. For printed boards, the calibration image must be printed at the correct physical size. Printer scaling such as “fit to page” must be disabled. Before using a printed board, check that: * the print was made at the correct physical size * printer scaling was disabled * the board is flat and stable * the printed pattern is not bent, warped, or damaged * the board dimensions match the configured size in Grid Studio A printed board can be a very accurate calibration reference if the physical size is known and the board remains stable during calibration. *** ## Projection-Based Workflows Projection-based calibration images are not part of the standard Calibration Screen workflow. With a projection, it can be difficult to guarantee the final physical size of the projected calibration pattern. The projected image may change depending on projector distance, lens shift, keystone correction, surface angle, focus, or projector settings. Because of this, the standard Calibration Screen workflow expects the calibration image to be displayed or placed on a known physical reference surface where the final size can be controlled accurately. If a projection-based setup is used in a special workflow, the projected image size and geometry must be measured and controlled separately. *** ## Screen Objects in Grid Studio Calibration Screens are represented by Screen objects in Grid Studio. The Screen object defines the virtual representation of the physical reference surface. This includes information such as size, resolution, and screen setup. Screen objects are usually created and configured before starting the calibration. Calibration tools do not create the Screen objects themselves. Instead, some tools can calculate and apply the placement, orientation, or shape of existing Screen objects in 3D space. This means: * the Screen object must already exist * the size and basic setup must be configured correctly * the calibration tool can optionally update where the screen is located in the virtual scene * the calculated result is applied to the existing Screen object *** ## Single Screen and Multi Screen Setups Calibration Screens can be used in single-screen or multi-screen setups. Use a **Single Screen Setup** when the reference surface is one flat surface, such as: * one monitor * one TV * one printed board * one flat LED wall section {% content-ref url="/pages/iN4Ng7xCeszso2El9Tpl" %} [Single Screen Setup](/grid/camera-calibration/before-you-start/calibration-references/calibration-screens/single-screen-setup.md) {% endcontent-ref %} Use a **Multi Screen Setup** when the reference surface is made from multiple connected or separated screen parts, such as: * tiled LED walls * multiple LED columns * several connected screen sections * complex LED stage layouts The following sections explain how to configure Single Screen and Multi Screen setups in more detail. {% content-ref url="/pages/lAaa3oKx8o4m93O2I2qF" %} [Multi Screen Setup](/grid/camera-calibration/before-you-start/calibration-references/calibration-screens/multi-screen-setup.md) {% endcontent-ref %} *** ## Before Using Calibration Screens Before using Calibration Screens in a calibration workflow, make sure that: * the physical reference surface is stable * the physical size is known * the Screen object in Grid Studio uses the correct dimensions * the calibration image matches the target resolution * digital screens display the image pixel-correctly * printed boards are printed at the correct size * the complete calibration image is visible in the camera image * the reference surface is not moved during the calibration process Once the Calibration Screen is prepared, it can be used by the calibration tools as a known reference for solving lens, tracking, screen placement, or alignment data.