In the previous version of this project, the geometry and animation were modeled after the male, Schizocosa uetzi species of wolf
spiders. Because of this, the movement of the spider was limited to the
right foreleg only. However, to extend the use of this virtual spider
animation, control of the left foreleg was needed as well, since the other
species under study (i.e., s. duplex, s. stridulans, and s. crassipes)
display movement in both forelegs during courtship. As a result, this led
to further extensions to the Matlab GUI as well as the animation model of
In addition, upon further investigation, Eileen Hebets recognized the use
of this spider was not limited to the male species in her research. Another
area that had never been explored before included studying the courtship
displays between a virtual female spider with a live male spider specimen.
That is, reversing the roles between the gender that is displayed on video
versus the gender of the live specimen under study could now be easily
achieved. Thus, another extension made in this project includes animation
of a female spider. Since the user can easily modify the geometry through
the Matlab GUI, differences in morphological traits between the genders did
not need further enhancements.
See Usage section to download the
spider simulation with extended features.
In order to support the extended features above, the
animation now includes movement in the front two leg pairs depending on
the gender and side selected by the user. If the male is chosen, the
user is allowed control over the 2 front forelegs (i.e., leg pair I).
If a female spider is chosen, the user must also choose between the
left and right side. This will enable movement of 2 legs as well.
However, female courtship displays include synchronized movement of the
2 legs (one leg each in leg pair I and II.) In addition, the
synchronized movement must consist of 2 legs on the same side. See Demos section for examples illustrating
the differences between the genders.
2 Matlab GUI
The user interface has been extended with the following features:
2.1 View Submenus
The View Menu options have changed to include a submenu for the gender and one for the species.
No further action is necessary after selecting a
gender. That is, the action will be automatically applied to the spider
in mid motion. To reset the legs, stop the animation before selecting a
gender. This can be done through the 'Play->Stop' menu option.
Then select the gender of interest, and restart playing of the spider.
This is an added submenu to separate the viewing of
species from that of the genders. All items in the species submenu
maintain the same functionality as before. See section Matlab GUI, Section 1.1.2
2.2 Spline Graph
panel of the Spider GUI has been modified as well. Radio buttons were
added here to allow for the user to select between the left and right side.
The spline graph displayed will correspond to the data points for the side
that is chosen. That is, the spline graph displayed now depends not only on
which leg joint is chosen, but also on which leg the user selected. This
will allow for manipulation on all 8 leg joints (4 joints for the right
leg, and 4 joints for the left leg).
Since there are now essentially 8 joints to track time steps for in the
animation, the amount of data that will need to be passed from the matlab
GUI to the OpenGL will essentially double. Specifically, the vars array data structure
in Matlab will contain 482 more data points than before, for a total of
1115 data points. Since both legs can move, an additional 480 interpolated
data points are needed to track the angle at which each joint is positioned
on each time step for the right leg (4 leg joints * 120 data points for
each joint). In addition, 2 additional data points are needed to track the
gender and the side that is selected by the user.
The rendering in OpenGL has pretty much remained the same as before. Changes
here primarily deal with the additional data points involved in calculating
the position of the 2nd leg. If the user selected a male spider, the side
does not matter since both legs can potentially move. Movement in the right
leg can be differentiated with movement in the left by the data points that
are passed in through the MEX-Array.
The following .avi files demonstrate the differences in courtship
display behaviors of each gender.
The image on the left is of a male spider. Notice both front forelegs are captured in mid motion. This can be contrasted to the image on the right of a female spider, where leg pairs I and II are affected, but movement occurs on only one side of the spider.