Floor Projection¶

This tutorial explains how to configure SPARCK for a floor projection using two calibrated projectors.

Calibrating the projectors is essential for correctly blending their images on the floor using a SpatialShadery node. Accurate calibration aligns the projectors with the virtual scene, ensuring that projected virtual elements display, track and move in perfect sync with real-time generated content.

Download the project files here: Floor_Projection.zip

Setup with 2 projectors¶

In your Max patch, add SPARCK. See Getting Started for more information.

SPARCK for this setup

The image below shows the overall Max subpatcher p Workspace, which contains all the SPARK nodes required for this configuration.

Floor projection SPARCK setup

A Canvas set as a floor with streamed Spout content

Window node, output preveiw. In this preview, the Grid is also visible and the Beamer have indentify toggled

Nodes Configuration¶

The following sections describe how to correctly set up all the necessary nodes for a floor‑projection configuration.

Window Node¶

The Window node outputs the rendered result of SPARCK to the output devices — in this case, two projectors.

Window node. Available under 01_UTILITY > WINDOW.maxpat

position: Switch between Output and Desktop. Output displays the visual content on the configured projectors, while Desktop creates a preview window that shows how the content is distributed across the Beamer nodes.

columns and rows: Slices the Window into designated frames. Here, 2 columns and 1 row are used to match the two Beamer nodes.

display: Press setting... to open the display setup tool and configure the total projection resolution. Select the display(s) you want to use — selected displays appear orange. Click Store and Close when done.

Beamer Node¶

The Beamer node creates a virtual projector inside SPARCK's 3DViewer. It is essential for calibrating the projector's position, orientation, and lens properties in relation to physical space. See Calibration for details on calibrating a Beamer.

The Beamer node is connected to the Viewport node. TODO: Why?

Beamer node — 02_SPACE > BEAMER.maxpat

capture: Select the render layer where the Beamer output is displayed. Make sure only one small turquoise square is active for each Beamer.

calibfile: Create and save a .xml file that stores the Beamer's calibrated position and lens data.

calibrate: Launches the calibration editor. See Calibration for more information.

identify: If enabled (turquoise square), displays a color background in both Output and Desktop windows to identify which projector is active, using color information stored in the calibfile.

gizmo: When enabled (large turquoise square), displays the projector gizmo in the 3DViewer at its calibrated virtual position.

Viewport Node¶

The Viewport node creates a texture that is sent to the Window.

Viewport node — 01_UTILITY > VIEWPORT.maxpat

window: References the Window node.

slice: Selects the designated slice where content will be displayed. The first Viewport uses column_1, row_1; the second Viewport uses column_2, row_1.

mesh: Set to default. This ensures that the texture fits the Beamer resolution, especially when tfm type is normalized.

SpatialShadery Node¶

The SpatialShadery node is at the core of Spatial Augmented Reality. It computes per‑projector pixel visibility and brightness, producing soft‑edge blending across all projectors.

SpatialShadery node — 07_EFFECTS > SPATIALSHADERY.maxpat

shader: Use edge & blend for soft‑edge merging.

project to: Set to baked textures.

Beamer A–D: Assign each Beamer.

projection: Use both side.

spread: Controls the distribution of pixel blending between overlapping projections. 0 = no spread, 1 = full spread. Find a good balance that fit your situation.

distance: Controls the distance as an additional differentiator. It will show its influence when the spread is increased. 0 = no distance, 1 = full distance. Find a good balance that fit your situation.

output: Set to result to display final blended output.

power: Controls the soft-edge blending power. Find a good balance that fit your situation.

luminance: Adjusts the brightness balance. Find a good balance that fit your situation.

Canvas Node¶

The Canvas node can draw a variety of basic 3D shapes such as planes, cubes, spheres, or custom meshes. It is a lightweight version of the Model node and does not include material, lighting, or shadow settings. Here it is used to create a simple plane on which content will be projected. A SpoutReceiver node is connected to the Canvas node.

Canvas node — 02_CANVAS > CANVAS.maxpat

drawto: Selects the render layer where the Canvas is displayed. In this setup, the Canvas is visible in the 3DViewer and in the Beamer output layers.

Preview of the floor using a Canvas.

shape: Select a base shape. A plane is used here, though other shapes such as spheres or cylinders can be used.

shader: Select the shader to apply. Here, the SpatialShadery shader is used to ensure both projectors contribute correctly with soft‑edge blending.

scale: 1 SPARCK unit equals 1 meter (100 cm). The plane is scaled to match the IAS floor plan (6m wide × 12m long). Correct scaling ensures alignment between virtual projection content and real‑time visuals from engines such as Unreal or TouchDesigner.

SpoutReceiver Node¶

The SpoutReceiver node receives real‑time textures from Spout, typically generated by visual engines like TouchDesigner, Unity, Unreal, or Notch.

SpoutReceiver node — 05_INPUT > SPOUTRECEIVER.maxpat

sender: Select the Spout video stream.

flip x: Flip the incoming texture horizontally.

flip y: Flip the incoming texture vertically.

Model Node¶

The Model node is used to display a simplified but accurate 3D model of the Immersive Arts Space inside the 3DViewer, helping visualize projector and floor positions. It is disabled here because it is not required for the projection setup.

Model node — 02_SPACE > MODEL.maxpat

drawto: Selects the render layer (large turquoise square). Here, the Model appears only in the 3DViewer.

In white, a simplified accurate 3D model of the Immersive Arts Space dispayed inside SPARCK 3Dviewer, also displayed the floor canvas and the grid

meshfile: Loads a 3D model from Sparck/_assets/_models. Ensure to keep the polygon count reasonable for good performance.

Grid Node¶

The Grid node is a helper tool used to display a reference grid in SPARCK. It is disabled here but can be enabled for checking projector calibration accuracy: if the grid lines from both projectors overlap cleanly, calibration is good; if they appear doubled or misaligned, calibration needs adjustment. See Calibration for more information.

Grid node. Available under 02_SPACE > GRID.maxpat

drawto: If enabled (large turquoise square), selects the render layer where the grid is shown. In this setup, it is visible only in the 3DViewer, but it can also be shown through the Beamer outputs if needed, especially to check calibration accuracy.

Grid dispayed inside SPARCK 3Dviewer

scale: 1 SPARCK unit equal to 1 meter (100cm). In this case it maches the IAS floor plan (6m whide and 12m long).

render gridsize: Adjusts the size of the grid subdivisions.

showaxis: Enables or disables the Grid axis display.
Grid exis enabled, preview inside SPARCK 3Dviewer