Field Manual: Interpreting pattern match results

You can access the results of a pattern matching scan (a.k.a. scanTask) by:

  • Clicking View for a completed scanTask in the sharkGrid Administration page
  • Clicking Groth: Left/Right-side scan results or I3S: Left-side scan results from the related encounter page

The results are displayed in two tabs: Modified Groth and I3S.


Figure 1. Scan results

Modified Groth results

Details for the inner workings of the Modified Groth algorithm are available in the paper:

Arzoumanian, Z., Holmberg, J. & Norman, B. (2005) An astronomical pattern-matching algorithm for computer-aided identification of whale sharks Rhincodon typus. Journal of Applied Ecology, 42 (6), 999-1011.

The Modified Groth results are displayed in two areas:

1. Metric results

Metric results provide the quantitative and qualitative results of the algorithm.


Figure 2. Metric results for the Modified Groth algorithm

The metric results for each comparison are ranked from best potential match to least. The listed values are:

  • Shark - The shark that the potentially matching pattern belongs to.
  • Encounter - The encounter with the potentially matching patten.
  • Fraction matched triangles - The fraction of matched triangles between the two spot patterns. Possible values range from 0 to 1. The higher the value, the stronger the match.
  • Match score - The final match score, as described in Arzoumanian et al. The higher the value, the stronger the match.
  • logM std. dev. - The standard deviation of the logarithm of magnification differences between matched triangles in the two spot patterns. The lower this value, the stronger the match.
  • Confidence - The qualitative confidence of the match.
  • Matched keywords - The photo keywords that both potentially matched encounters share in common.

2. Visual results

The visual results for the Modified Groth algorithm display matched spots between potentially matched patterns. To compare results, look for each colored spot on the left to match a corresponding spot in the pattern on the right. Click Next and Previous to tab through potential matches in order of match score.


Figure 3. Visual results for the Modified Groth algorithm

I3S results

1. Metric results

Metric results provide the quantitative and qualitative results of the algorithm.


Figure 4. Numeric results of the I3S algorithm

The metric results for each comparison are ranked from best potential match to least. The listed values are:

  • Shark - The shark that the potentially matching pattern belongs to.
  • Encounter - The encounter with the potentially matching patten.
  • Fraction matched triangles - The fraction of matched triangles between the two spot patterns. Possible values range from 0 to 1. The higher the value, the stronger the match.
  • Match score - The final match score, as described in Van Tienhoven et al. The lower the value, the stronger the match. Values of “0.0” should be ignored.

2. Visual results

The visual results for the I3S algorithm display matched spots between potentially matched patterns. To compare results, look for each colored spot on the left to match a corresponding spot in the pattern on the right. Click Next and Previous to tab through potential matches in order of match score.


Figure 5. Visual results for the I3S algorithm

 
scan_results.txt · Last modified: 2008/07/04 04:04 by webadmin     Back to top