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Visualization-directed interactivemodel-fitting to spectral data cubes
CRICOS provider 00111D

Christopher Flukewith Jayanne English (U. Manitoba)
David Barnes (Swin)
Ben Barsdell (Swin), Amr Hassan (Swin)ADASS 2009: Sapporo, Japan

Spectral Data Cube: Definition• Dimensions:• 2 spatial + 1 “spectral”• (Often) Gridded data:(x, y,λ)(x, y,ν)(x, y, vlos)
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ADASS 2009

Visualization-Directed Interactive Model Fitting2Sources of Spectral Data Cubes
Radio telescope• Aperture synthesis• Mosaic• Multibeam

Optical/IR• Scanning Fabry-Perot• Scanning long slit
• Integral field units• (Multi-object spectrographs)© Swinburne Astronomy Productions

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Visualization-Directed Interactive Model Fitting

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Simulation to Spectral CubeJohn Hibbard (NRAO) ImageJohn Hibbard (June 2008)

6-d model space
Space: (x,y,z)
Velocity: (vx,vy,vz)
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3-d observation space
Space: (x, y)Line-of-sight velocity: (vlos)

Visualization-Directed Interactive Model Fitting

4Automated Approaches

M83: Rogstad et al. (1974)

Figure 8: 3D Model

Figure 9: Projected on sky

Figure 10: HI map• Differentially rotating HI diskse.g. Rogstad et al. (1974); Begeman (1989)• 4 parameters: Vsys, Vcirc, i, ϕ as function of radius• Warps? Anomalous gas? Mergers?
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Visualization-directed Approach
Build and visualizeinteractive models
toenhance intuition
andenable fitting
and analysis
ofcomplex kinematicalstructures
fromspectral data cubes
From Canadian Galactic Plane Survey/DRAO. Courtesy J.English

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Visualization-Directed Interactive Model Fitting

6Computation
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6-d model space

3-d observation space

Camera projection from orientation(x,y) preserved

Calculate vlos from v = (vx, vy, vz)
Add to spectral cube voxel

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Technical Requirements• Interactive frame-rates• Real-time updates• Handle simulation and data
• Volume rendering andisosurfaces• Support stereoscopic displays• Support 3D publication• Simple application development
S2PLOT: Barnes et al. (2006) www.astronomy.swin.edu.au/s2plot
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Visualization-Directed Interactive Model Fitting

8Comparison with LightWave

Modeler

Layout: Render

Synchronization via LightWave Hub
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S2PLOT Elements
Handles: cs2hcb()

Screen: ss2tsc()

Camera: ss2qc()
Isosurface:ns2cis(), ns2dis()Volume Render:
ns2cvr(), ds2dvr()
Points: ns2point()
Callbacks: cs2scb ()Panels: xs2mp(),xs2ap(), xs2pp()

Coordinates: s2box()
Text: s2textxy()
Draggable Handles: ds2ah(), cs2sdhcb()

Lines: ns2line()

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Visualization-Directed Interactive Model Fitting10Model Elements, Controls and Tools• Vsys• Interactive Rotation curve• Interactive Density profile• Models:• Rotating disks• Expanding shell• N-body galaxies (Gadget)• Warps• Hot spots• Jets• Noise!
• Quantitative tools: 3-d Cartesian Shapelets
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Visualization-Directed Interactive Model Fitting

11Cartesian Shapelets: Refregier (2003)+1+1B0+0.5+0.5+1B1+0.5

000-0.5-0.5-0.5-1-1-1-5+1+0.5

0+5-5+1B3+0.50+5-5+1B4+0.5

000-0.5-0.5-0.5-1-1-50+5B20+50+5B20-1-50+5-5

Figure courtesy: Adrian Malec (Swinburne)

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Figure courtesy: Adrian Malec (Swinburne)

2-D Shapelet Reconstruction

Original Image• Image simulation (Massey et al. 2004; Ferry et al. 2008)• Morphological classification (Kelly & McKay 2004; Young et al. 2005)• Weak lensing (Refregier & Bacon 2003; Kuijken 2006; Massey et al. 2007)
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3-d Cartesian Shapelets (Fluke, Malec, Barsdell, et al. in prep)
ϕ3,(000)

ϕ3,(010)

ϕ3,(202)

ϕ3,(124)ADASS 2009

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3D Cartesian Shapelets (Fluke, Malec et al. in prep)

Input ModelADASS 2009

Reconstruction(GPU!!)

Visualization-Directed Interactive Model Fitting

Residual15

Next steps…
Visualization (Amr Hassan: Poster #27)
• S2PLOT prototype - only suitable for small cubes• Integrate with GPU volume rendering framework
General-Purpose GPU Computing (Ben Barsdell: Poster #4)• “Real-time” model fitting• Advantages in using GPU = highly parallel computation

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Visualization-Directed Interactive Model Fitting

16Summary
Knowledge
Discovery

Data
Characterise Data

Generate Model

Compare with Data

• Isolate regions• Identify velocity ranges• Choose resolution• Noise properties• Simple components• N-body simulations• Tools/Controls• Modification history• Shapelet model• Virtual observation• Add noise• Residual map• Qualitative• Quantitative

S2PLOT: real-time, interactive, 3-d
Publish via 3d-PDF

S2SLIDES: Presentation

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Visualization-Directed Interactive Model Fitting

Stereoscopic Displays
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