Room Dimension Measuring App

I’m building a mobile app that lets anyone point a phone camera at a room, capture either a set of photos or a smooth video walkthrough, and immediately see precise length, width, and height readings—plus a clean 2-D floor plan—right on the screen. The app must run natively on both Android and iOS and handle either input mode interchangeably, detecting which media type the user supplies and processing it automatically.

Here’s the core workflow I need implemented:

1. Media capture

• Photo series or continuous video, initiated inside the app with clear guidance overlays.
2. 3-D reconstruction

• Apply state-of-the-art computer-vision (depth estimation, photogrammetry, or AR—whichever you judge most accurate and efficient on modern devices) to build a room mesh in real time or near-real time.
3. Measurement extraction & display

• Derive wall-to-wall distances and ceiling height in centimetres/metres with ≤2 % error in typical indoor lighting.
• Render a simple 2-D floor plan annotated with those measurements and allow export as PDF/PNG.

Deliverables
• Fully packaged Android (Kotlin/Java) and iOS (Swift/Objective-C) apps ready for TestFlight / internal testing
• Source code with clear comments and build instructions
• Brief technical document explaining the chosen CV pipeline, calibration approach, and accuracy benchmarks

Acceptance criteria
• I walk through a 4 m × 3 m × 2.5 m room once with my phone; the app outputs dimensions that deviate by no more than 5 cm in either direction.
• Floor-plan export opens correctly in common viewers.
• App does not require external hardware beyond a standard recent smartphone.

If you have prior experience with LiDAR, ARCore/ARKit, or open-source photogrammetry libraries such as OpenCV, OpenMVG, or COLMAP, please highlight it when you reply. I’m happy to discuss technical preferences and iterate on milestones together.