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Detection of Line-shaped Tracks in Images with DADD. STScI. Peter R. McCullough Jul 21 , 2011. How fast we are progressing…. 2007, First Map of an Alien World, SST press release for Nature article of Knutson et al. 2009, Alien Maps of an Ocean-bearing World, ApJ title of Cowan et al.

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detection of line shaped tracks in images with dadd

Detection of Line-shaped Tracks in Images with DADD

STScI

Peter R. McCullough

Jul 21, 2011

how fast we are progressing
How fast we are progressing…
  • 2007, First Map of an Alien World, SST press release for Nature article of Knutson et al.
  • 2009, Alien Maps of an Ocean-bearing World, ApJ title of Cowan et al.
  • 2011, Observational Evidence of Sentient Life on an Earth-like Planet, TIPS alternative title of McCullough
how fast we are progressing1
How fast we are progressing…
  • 2007, First Map of an Alien World, SST press release for Nature article of Knutson et al.
  • 2009, Alien Maps of an Ocean-bearing World, ApJ title of Cowan et al.
  • 2011, Observational Evidence of Sentient Life on an Earth-like Planet, McCullough (this work)
dadd brought to you by

DADD= Doubling Accumulation Drift Detection

DADD brought to you by …
  • Jill Tarter, JHU seminar 2004-2005
  • Richard Stauduhar(1940-2010), mathematician for the SETI Institute and U.C. Berkeley Space Sciences Lab, private communication 2005.
  • Cullers & Deans 1992, unpublished*, cited by

Backus, P. R. 1993, The NASA SETI Microwave Observing project Targeted Search, in Third Decennial US-USSR Conference on SETI, ASP Conference Series, Vo. 47, p. 323.

  • SetiQuest.org, sonata-1.0.16.zip

* thanks to Jill Lagerstrom (and the authors) for obtaining a scanned copy of this unpublished report.

slide5

Line-shaped streaks (from bright lights on Earth) appear in ~30% of HST WFC3 observations of the dark-side of Earth, (taken for flat fields, to be described in a future TIPS). DADD automates flagging of pixels within streaks.

dadd doubling accumulation drift detection
DADD = Doubling Accumulation Drift Detection

M spectra, each with N channels

Requirement of slow drift: |slope| > 1

Mathematical operations:

Brute force: ~2NM2

DADD: ~2 NM log2 M

DADD accumulates pairwise like the FFT ;

DADD reuses sums of pixels common to multiple lines across the 2-D array.

To apply DADD to 2-D imagery, we analyze the image successively four times with rotations of 0º, 90º, 180º, and 270º in order to detect trails of arbitrary slope and origin.

M Times

N Frequencies

dadd doubling accumulation drift detection1
DADD = Doubling Accumulation Drift Detection

0 0 continuous functions:

0 1 all steps = 0 or 1 channel

00 00 0001constant derivatives

00 11 0111

01 12

01 23

0000 0000

0000 1111

0011 1122

0011 2233

0112 2334

0112 3445

0123 3456

0123 4567

M Times

N Frequencies

dadd is sensitive quick
DADD is sensitive, quick,

Execution time per track identified

= 0.7 seconds per megapixel

= 2.8 s for 2048x2048

dadd is sensitive quick and stands alone
DADD is sensitive, quick, and stands alone

Execution time per track identified

= 0.7 seconds per megapixel

= 2.8 s for 2048x2048

C code operating on 16-bit FITS 2-D images, with an IDL wrapper to facilitate pre-processing and post-processing analysis.

(WFC3 ISR coming soon)

summary dadd can be used for detection of
Summary: DADD can be used for detection of …

SETI signals, e.g. weak, drifting narrowband CW signal in time series of RF spectra

Streaks across dark-Earth flat-fields (as illustrated)

Cosmic ray trails*

Asteroid or satellite trails*

Bleeding (overexposed PSF) trails* ^

Slitlessgrism spectra* ^

* DADD is less sensitive to shorter line segments.

^ DADD is probably overkill where orientation of trails is fixed and known a priori.