G11-2025

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h1. Multi‑Projector System — Project Wiki

Overview
Our goal is to build a two‑projector system that displays seamless still images on a flat screen, where the projected areas overlap and must be blended. Implementation is in Python (OpenCV). Prior to implementation, we document the problem and a viable solution approach. #Scope #Work-Packages #Team¶

Problem background (why blending matters)
Overlapped regions become over‑illuminated; alpha‑blending with proper masks evens illumination across seams. (See slides: “What is alpha‑blending?”) Alpha‑blending¶

Scope & assumptions

• Start from a planar screen with two projectors; optical axes perpendicular to the screen.
• Work with still images first (not video).
• Expected overlapped area is approximately rectangular; target a linear drop of mask intensity from 1→0 across the overlap.
• Use Python + OpenCV; iterate from simple to refined.
  (From project brief and simplified requirements.)

Objectives

• Describe the problem and identify a potential solution before coding.
• Apply geometric reasoning (lines/planes in 3D; ray‑plane/ray‑cylinder intersections) as needed.
• Prototype masking that yields smooth, artifact‑free blending.
  (From “Objective”, “Skills required”, and problem formulation.)

Key concepts & references

• Alpha‑blending — concept and examples.
• Forward (screen→projector) and inverse (projector→screen) ray tracing for overlap detection and mask generation.
• “Smooth” masks prevent scratches along mask boundaries.

Work packages (WPs)

• WP1 – Geometry & Calibration
  Define screen and projector geometry; set initial positions; document assumptions and coordinate frames. Deliverable: short calibration note and diagram.
• WP2 – Overlap Detection
  Use forward/inverse ray tracing to detect dual‑illumination pixels on the screen. Deliverable: mask preview images for each projector.
• WP3 – Mask Generation & Blending
  Implement linear (then smoothed) alpha masks across the overlap; verify no “scratches” at boundaries. Deliverable: blended still‑image demo.
• WP4 – Experimentation & Evaluation
  Record test setups, parameters, and visual results; checklist for “uniform illumination”.
• WP5 – Documentation
  Maintain this wiki; Doxygen comments in code; weekly log.

Milestones & deliverables

• M1: Geometry & calibration draft (WP1).
• M2: Overlap detection working on synthetic image (WP2).
• M3: Smooth masks + blended demo on screen (WP3).
• M4: Evaluation report + next‑step plan (WP4, WP5).

Team & roles (click a name to open their profile)

Role	Amount	Who
Advisor	1	Great Gilbert Soco
PL, Project Leader	1	Koki
PM, Project Manager	1	Noah
Redmine – supporter of PM	1	Nonoka
Developers	2–3	Deng, Gilbert
Doxygen Leader	1	Hachiko (Haziq)
Doxygen, commenters	2	Jordan, Hazel, Sota
Wiki Leader	1	Gilbert
Wiki Developers	2	Zoya, Phillip Anderson
Jira Research Team	2	Zack, Phillip Anderson

Tip: create each profile page the first time you click a name.
p=. Back to top: ↑

Alpha‑blending (notes)
Overlapped areas without masks are brighter; masks weight each projector so the sum equals uniform brightness. Smooth masks eliminate boundary scratches; see examples in the slides.¶

Project links

• Requirements & assumptions: this page, sections #Scope and #Objectives.
• Design notes & diagrams: (create) Design-Notes
• Experiments log & photos: (create) Experiments-Log
• Code repo / file list: (link later)