Transcript Slide 1

Software design and user feedback in the development of DARWIN
John H. Stewman and Kelly R. Debure, Eckerd College.
Abstract
Saving a trace
DARWIN (http://darwin.eckerd.edu) is a computer program developed to
facilitate the identification of individual dolphins from photographs of their
dorsal fins. Users query a digital catalog of photographs of individual
dolphins to produce a rank ordered display of images identified as most
similar to the query image. Thus, the software attempts to reduce the
number of images a researcher must examine to identify a particular
individual. Software development without early and continuing input from
end users can lead to a final product which is cumbersome and non
intuitive, if useful at all. Complex software such as DARWIN must be
tested in a manner that emulates its actual usage as completely as
developers can manage. Usage environments can differ significantly with
respect to database size, image size and quality, and perhaps most
significantly established protocols for manually processing data and user
preferences related to computer usage. Something a simple as an
awkward key or button sequence can make the accomplishment of a
desired outcome pleasant or tedious. Moreover, as technology changes
and research groups adopt different standards for gathering and
maintaining field data, the software must also adapt. Always, the goal is to
facilitate the efficient processing of photographs, to the extent possible.
This discussion of our experience with the design and development of
DARWIN focuses on feedback from users of initial beta releases of the
software and from our collaboration with the Eckerd College Dolphin
Project. We detail some of the significant changes and features suggested
by current and potential users.
In addition to identifying individuals from a sighting against a database of
known individuals, dolphin researchers occasionally want to compare entire
catalogs against themselves or
one another. To prevent the need
to trace the outline twice, once for
the creation of the catalog and
once for the creation of the query
outline, the current software
provides the ability to save a
traced fin for later use. The trace
of the outline and its associated
image can either be loaded to
create a catalog or to search for a
match in the catalog. A trace can
also be saved for batch processing
as described below.
Figure 1: The window above shows an image and its
Outline generation
Most dolphin research groups currently use off the shelf software to display,
organize, enhance and/or transform their digital images for comparison. In
order to offer an attractive alternative to these products, DARWIN must
reduce the time it takes to identify an individual (on average) and must not
require significant additional work from its users; otherwise the useful "tool"
becomes an onerous "task". The DARWIN software uses dorsal fin outlines
in the comparison of one fin to another. The detection of a fin outline in an
image can be initiated by using the mouse to indicate its general image
placement. This placement is then refined automatically with the use of
active contours. Even though this semi-automated process works well and
requires only a few seconds of user input, the initial task of tracing outlines
can be laborious over a large collection of images. Therefore, all beta
releases of the DARWIN software have included a fully automatic method of
generating fin outlines. If this autotrace fails, the user can always retrace
using the semi-automated approach. In our testing of 302 images,
approximately 68% of the autotraced outlines were useful. Feedback from
one group who experimented with the software had much less success. Our
examination of their images, showed that simply cropping to minimize
foreground glare significantly improved results. We conclude that clearer
documentation about how to make the software work well will be invaluable.
outline which has been traced during one interactive
session and reloaded during another.
Flipping/zooming/overlay
Running multiple matches in queue mode
Once a catalog has been created and
a trace has been extracted from the
dorsal fin in a sighting image, the
process of matching can proceed.
Although the software makes
individual comparisons fairly quickly,
generating a ranked list of matches
against a large database can take
minutes rather than seconds. On a
typical 1.6 GHz laptop running
Windows XP, the software takes about
20 seconds to create the ranked
listing from a database of 200 fins.
Initial users of the beta release
inquired about the ability to submit the
match requests as a batch process
and reload the results for viewing
later. This feature has been added.
In order to enable an automatically generated outline to be created, the image may be
contrast enhanced and cropped to include only the dorsal fin. Although these enhancements
may improve the ability of the software to extract an outline, they may hide or de-emphasize
features used by biologists for comparison of the dorsal fins. Thus, when displaying the
match results, DARWIN displays the modified, cropped images by default, but users may
alternatively display the original image for comparison. Also, the orientation of the displayed
fins can be changed for ease of comparison. Efforts are currently underway to enable the
sighted fin to be displayed such that it appears to have been photographed from the same
angle as the catalog fin to which it is being compared. Suggestions have been made to
combine this utility with the ability to overlay the two aligned images to facilitate comparison.
Ranking of Unknown Fin's Identity
(as percent of database size)
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Figure 2: In the window above, a queue of
three outlines has been created for batch
processing of matches against the catalog.
Progress bars indicate the percentage of the
matching which has been completed.
Number of query fin images
Initially, DARWIN was developed with the intent of reducing the tedium
associated with the manual identification of individual dolphins using a print
catalog. Most groups were using slide film to photograph dolphins in the
wild and the bottleneck of scanning the slides was a deterrent to use of an
automated method of identification. As the price of digital cameras has
dropped and the available resolution of those cameras has improved to that
of film quality, the possibility of using computer software tools to aid in the
identification of individuals has become much more appealing and
widespread.
Figure 3: The window which displays the rank ordered list of matching images has been
redesigned to prioritize display of larger images, thus facilitating their comparison.
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Ranked position of correct fin image
Accuracy
Bigger pictures
Viewing the results of a match (the ranked list of catalog images) is enabled
in a side by side display of the unknown sighting image and each image in
the catalog. Our discussions with Dr. Shannon Gowans of the ECDP made
one thing clear: when displaying images of dorsal fins, bigger is better. The
current software has a match results window that has been completely
redesigned to maximize the screen space allocated to the side by side
display of the images.
As catalogs become large, the click of a single button to view the next
image can become tiresome and monotonous. It has been suggested,
again by Dr. Gowans, that a slide show viewing option be added to the
window which displays the match results. This function is being
incorporated.
As the software has continued in testing, we have made several minor adjustments to the fin
registration (mapping) and ranking code in attempts to further improve the quality of the
mappings and the accuracy of the final rankings of the match. The tip position is now less
constrained in the iterative mapping process and this has led to results as follows. A test set
of fifty “unknown” individuals was compared against a catalog of 200 individuals. Forty one
of the fifty queries produced rankings in the top 5% of the catalog. Of these, 21 queries
ranked the correct fin first. On average, the query placed the correct fin in the top 5% of the
catalog, with a median ranking in the top 1%.
Acknowledgements
The authors would like to thank Dr. Shannon Gowans and the students of the ECDP, the
folks at the Harbor Branch Oceanographic Institute and the Duke Marine Lab, and Dr. Hal
Whitehead for their considerable feedback and suggestions. We would also like to thank the
National Science Foundation for funding of this research under grant number DBI-0445126.