Z-Tiles: Building Blocks for Modular, Pressure-Sensing Floorspaces Bruce Richardson, Krispin Leydon,...
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Transcript of Z-Tiles: Building Blocks for Modular, Pressure-Sensing Floorspaces Bruce Richardson, Krispin Leydon,...
![Page 1: Z-Tiles: Building Blocks for Modular, Pressure-Sensing Floorspaces Bruce Richardson, Krispin Leydon, Mikael Fernström, Joseph A. Paradiso](https://reader036.fdocuments.us/reader036/viewer/2022062318/5517879755034645368b5373/html5/thumbnails/1.jpg)
Z-Tiles: Building Blocksfor Modular,
Pressure-Sensing Floorspaces
Bruce Richardson, Krispin Leydon, Mikael Fernström, Joseph A. Paradiso
http://www.idc.ul.ie/ztiles/
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Introduction
• New Pressure-
Sensitive Floorspace
• Successor to
Litefoot (1998) &
Magic Carpet (1997)
Paradiso et al. (1997) The Magic Carpet: Physical Sensing for Immersive Environments. CHI’97Griffith and Fernstrom (1998) LiteFoot: A Floor Space for Recording Dance and Controlling Media. ICMC’98.
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Authors
Bruce Richardson
Interaction Design Centre, UL.
Krispin Leydon
Interaction Design Centre, UL.
Mikael Fernström
Interaction Design Centre, UL.
Joe Paradiso
MIT Media Lab, Boston
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Requirement
Scalable => Modular and interchangable
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Requirement
Managable => Self-organising and reconfigurable
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Requirement
Real-Time => Fast scanning and fast output
• Scan at 100 Hz
• Low latency data routing
• Minimal network overhead
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Sensor Units
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Z-Tile Circuitry
![Page 9: Z-Tiles: Building Blocks for Modular, Pressure-Sensing Floorspaces Bruce Richardson, Krispin Leydon, Mikael Fernström, Joseph A. Paradiso](https://reader036.fdocuments.us/reader036/viewer/2022062318/5517879755034645368b5373/html5/thumbnails/9.jpg)
Z-Tile Architecture
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Floor Prototype
QuickTime™ and aDV - PAL decompressor
are needed to see this picture.
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Data Bottleneck
• Many wires vs. One wire• Bottleneck at connection point
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Options
1. Output only changed pressure readings
2. Group similar pressure readings
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Options
1. Output only changed pressure readings
2. Group similar pressure readings
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Blob Matching
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Considerations
• 100 pressure scans/sec
10ms maximum computation time
• Minimum number of parameters
• Accurate blob matching
• Trade off
Close “fit” vs Fewer parameters
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Ellipse Matching
• Circles:
Loose fit, few parameters
• Polygons:
Tight fit, many parameters
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Ellipses
Ellipses - good compromise
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Simple Matching
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Average -> Centre
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Axes -> Bounding Box
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Resultant Ellipse
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Results
• Pressures distilled to blobs
• 5 parameters per blob
• Implemented on a microcontroller
>800 scans processed per second
Rate achieved at 1/10 speed
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Evaluation
• Processing time to
spare
• Difficulty with
diagonal blobs
• Therefore, look for
better match
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Angled Ellipses
Pressure Readings We have We want
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General Method
• Determine centre
as before
• Locate 2 most
distant points
• Set this as major
axis
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General Method cont’d
• Rotate points so
axis is horizontal
• Use bounding box
to determine major
and minor axes
lengths
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Results
• Implemented on microcontroller
• Integer-only calculations
• Lookups for rotations
• Computation time 1-2ms
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Summary
• Blob detection to reduce data• 2 ellipse-matching algorithms• Run time on hardware: <2ms
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Future Work
• Integrate blob detection algorithm into tile software
• Detect blobs across tiles
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Questions?
http://www.idc.ul.ie/
http://www.idc.ul.ie/ztiles/