Photosynthby Microsoft Live Labs

C@CM PresentationTeam Members

Greg YoonSaki KoizumiMike PenrodHui Han ChinSoojin Yoon

Introduction

• Photosynth is an entirely new visual medium developed by Microsoft Live Labs.

Introduction

• It analyzes a set of photos of a place to discover similarities between the photos and uses that data to estimate where a photo was taken and build a model of the subject.

Introduction

• It then re-creates the environment and uses that as a canvas on which to display the photos.

History of Photosynth

• 2006: Microsoft acquired small, Seattle-area startup Seadragon

History of Photosynth

• Seadragon’s was capable of delivering a smooth experience browsing massive quantities of visual information over the Internet

History of Photosynth

• 2006: Groundbreaking research of Noah Snavely (UW), Steve Seitz (UW), and Richard Szeliski (Microsoft Research), developed a prototype called ‘photo tourism’, which form the basis of the synther in photosynth

History of Photosynth

History of Photosynth• November 9, 2006 : Microsoft released a free

tech preview version• August 6-20, 2007 : Microsoft teamed up with

NASA on allowing users to preview its Photosynth technology showing the Space Shuttle Endeavour.

History of Photosynth

• August 20, 2008, Microsoft officially released Photosynth to the public, allowing users to upload their images and generate their own Photosynth models.

Key Technology

• Feature Tracking• 3D Transformation • Geo Registration

How do humans compare?

Feature Tracking

• Algorithm of Choice: • Scale-space Invariant Feature Transform by

David G Lowe, (2000)• Most stable to affine transformation• Uses Difference of Gaussians to find extrema

across scale spaces as interest points

Feature Tracking

Feature Tracking

• Discover correspondence between pictures

3D Transformation

• Uses the Direct Linear Transformation Algorithm, Richard Hartley and Andrew Zisserman (2000)

Find the matrix H that describe the perspective transformation

3D Transformation – Scary math

Geo Registration

• Aligns the estimated position of the pictures with a GPS map of the location

Capabilities of photosynth

• Walk or fly through a scene to see photos from any angle

• Zoom in or out of a photo• See where pictures were taken in relation to one

another• Smoothly change viewing angle between nearby photos• Smoothly zoom in and out of high-resolution photos• Find similar photos to the one you're currently viewing• Send pictures

Demonstration

• http://photosynth.net/Default.aspx