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UI Issues, Neural Nets, RTS. CSE 490RA January 27, 2005. Lecture outline. Leftovers from UI Lecture Neural Networks RTS. Uses of the stylus. Direct writing Abstract writing Pointing Selecting Gesture Direct manipulation Control. Mode issues in pen computing.

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UI Issues, Neural Nets, RTS

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UI Issues, Neural Nets, RTS

CSE 490RA

January 27, 2005


Lecture outline

  • Leftovers from UI Lecture

  • Neural Networks

  • RTS


Uses of the stylus

  • Direct writing

  • Abstract writing

  • Pointing

  • Selecting

  • Gesture

  • Direct manipulation

  • Control


Mode issues in pen computing

  • Adding modes to the pen

    • Barrel button

    • Secondary button with non-dominant hand

    • Eraser tip

    • Pressure

    • Explicit mode buttons

  • Area based modes (writing area, gesture area, control area, etc.)

    • Cursor feedback

    • Importance of visual cues for informing user

    • Errors in crossing mode boundaries


Control

  • Widgets design for stylus use


Flow Menu

  • Use movement through octants for control information

Move

Item

100%

100%

Text

Item

Highlight

Zoom

66.6%

200%

66.6%

200%

Shape

50%

75.0

400%

50%

100.0

400%

25%

800%

25%

800%

Custom

Custom


Interaction with direct manipulation

Move

Item

Highlight

Zoom


CrossY: Crossing based UI

  • Specify operations by drawing through


Gestures

  • Commands issued with a single stroke

  • May be drawn or invisible

  • Support from SDK

    • Register gestures to be recognized

  • UI Issues

    • Similar to keyboard short cuts

      • Speed up for experts

      • Hard to learn / remember


Gestures

  • Ambiguity

    • Distinction between gestures

    • Distinction between gesture and other ink

  • Robustness

    • Handling misrecognized gestures

      • False positive

      • False negative

    • Gesture initiated actions should be undoable


Neural Networks

  • Fundamentals for Handwriting Reco Lecture (Jay Pittman)

  • Recognition algorithm

  • Learning based recognition algorithm


General considerations for learning algorithms

  • Training sets

    • Collection

    • Evaluation

  • Training cost

    • Time and space

  • Algorithm cost

    • Time and space

  • Robustness to error


Neural networksPerceptrons

  • Motivated by considerations of the brain


Single layer neural networks

  • Bias weights

  • Threshold activation function

    • Step function

    • Sigmoid function: 1/(1 + e-x)


What you can do with single layer networks

  • Any linearly separable dataset can be recognized with a single layer neural network


Gradient descent algorithm

  • Choose initial weights

  • While not at optimum

    • Compute derivative

    • Move along derivative

  • It can be proved this converges


However, single layer networks are very limited


Multilayer networks with hidden nodes

  • Can recognized much wider range of data set

  • The gradient descent algorithm generalizes to this case


Real Time Stylus

  • Allow for user computation on the ink thread


Architecture (Overview)

RealTime Event Sink

RealTime Event Sink

RealTime Event Sink

RealTimeStylus

Ink Collecting

Object

queue

storage

Pen

Service

InkCollector

“Inking” Thread

UI Thread


Substroke operations

  • Examples

    • Custom Inking

    • Multiple Ink

    • Distributed Ink

  • Rendering

    • Dynamic – draw on ink packet

    • Static – draw on paint event


Custom Inking

  • Create plugin to listen for packets

  • Registor for Packets

  • Draw triangle on each packet


public void Packets(RealTimeStylus sender, PacketsData data){

for (int i = 0; i < data.Count; i += data.PacketPropertyCount){

Point point = new Point(data[i], data[i+1]); // Packet data always has x, y

// followed by the rest

Point convertedPoint = new Point(); // We need to convert to Pixels...

convertedPoint.X = (int)Math.Round((float)point.X * (float)myGraphics.DpiX/2540.0F);

convertedPoint.Y = (int)Math.Round((float)point.Y * (float)myGraphics.DpiY/2540.0F);

if (this.pointCount == 0)

this.firstPoint = convertedPoint;

if (this.pointCount > 1){

Color color = pointCount % 2 == 0 ? Color.Red : Color.Yellow;

Point[] triangle = new Point[3];

triangle[0] = this.firstPoint;

triangle[1] = this.previousPoint;

triangle[2] = convertedPoint;

myGraphics.FillPolygon(new SolidBrush(color), triangle);

}

this.pointCount++;

this.previousPoint = convertedPoint;

}

}


Distributed Ink

  • Capture ink packets on machine 1

  • Send packets to machine 2

  • Reconstruct ink stroke by inserting packets


Sample application


Distributed Ink

  • Sender:

    • Collect packets in packet, when count is above threshold, send message

  • Receiver:

    • Insert packets as custom data

    • Render custom data as it is received

    • Assemble custom data as an ink stroke


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