Tele-GraffitiTele-GraffitiA Pen and Paper-Based A Pen and Paper-Based

Remote Sketching SystemRemote Sketching System

ByBy

P. Pradeep Kumar(08uq1a0435)P. Pradeep Kumar(08uq1a0435)

IntroductionIntroduction• Remote sketching system• Allowing two persons to

communicate remotely• Via hand drawn sketches

Remote Sketching SystemsRemote Sketching Systems

• Several ways: –Using a Tablet and a Stylus–Using a video camera and a projector

Hardware SpecificationsHardware Specifications• PC• Projector• Camera• Local Area Network

Tele-GraffitiTele-Graffiti

Tele-Graffiti System Tele-Graffiti System SoftwareSoftware

• Linux: RedHat 7.1• Four Threads:

– Drawing thread– Paper detection thread– Sending thread– Receiving thread

Drawing ThreadDrawing Thread• Continuously warps and draws the image to display• Image Warping

– OpenGL Texture Mapping

Paper Detection ThreadPaper Detection Thread• Grabs an image from the camera.• Detects or tracks the paper.• Updates the image to send and the

local paper vertices.• Notifies the Drawing thread of the

update.

Paper tracking algorithmPaper tracking algorithm1. Smooth the captured image2. Detect edges in the image3. Remove edges which come from the

projection of previous time steps4. Divide edge pixels into paper-clipboard and

clipboard-desk edges5. Estimate the paper orientation

Sending ThreadSending Thread• Converts the most recent image of

the paper at this site• Compresses it• Transmits it along with the estimated

local paper vertices in the image.

Receiving threadReceiving thread• Waits for the arrival of images and

paper vertices from the other Tele-graffiti site.

• Decompresses the image• Updates the image to display and the

remote paper vertices• Notifies the drawing thread of the

update.

ApplicationsApplications• Tele-Collaboration: two architects

communicating with each other remotely

• Remote education• Human-computer interaction: using

the paper as a combined display and input device.

REMOTE EDUCATION:

An instructor interacts with the student.

Human-Computer Interaction:

A user provides input to the web page.

ConclusionConclusion• Many ideas are best communicated

by drawing simple sketches. • If two people are located remotely

from each other a “remote sketching system" can help them communicate better. Tele-Graffiti is a remote sketching system.

Thank youThank you