rate (ranging from sixty frames/sec to one frame/min) appropriate for the 

 relative speed of the organisms. Wlien the BUGWATCHER INPUT operator is 

 executed, the computer accepts digitized image information from the 

 Bugwatcher at the selected frame rate. Each threshold point is represented in 

 Cartesian coordinates with 8-bit resolution for each of two orthogonal 

 components. A video frame is represented within the resultant data structure as 

 a data vector v/ith a variable number of such points as its data elements. An 

 entire record (or "video file") consists of a temporally ordered sequence of 

 such vectors. 



The Bugsystem was originally developed for the investigation of the 

 behavior of motile microorganisms (2). In this application, the organisms are 

 viewed under dark-field illumination swimming within a well slide upon the 

 stage of a compound microscope. However, automatic digitization of data is 

 possible for any study of moving objects for which "clean" video records are 

 available. One of us (Wilson) is currently using the second generation system to 

 study the effects of plane polarized light upon the behavior of aquatic 

 arthropods. The animals move freely within a cylindrical aquarium (diameter ^ 

 20 cm) under bright-field illumination and are viewed using a macro lens 

 attached to the television camera. Use of video tape as a storage medium allows 

 experiments to be conducted in a laboratory remote from the site at which the 

 data are analyzed. 



Occasionally video recordings are not "clean" enough to allow fully 

 automated digitization (e.g., data collected in the field) or the digitized images 

 are too crude to provide information about details of an organism's anatomical 

 structure (e.g., the orientation of its eyes). A technique has been developed to 

 expedite manual analysis of such data. Using the PICK operators, the video 

 tape is examined frame-by-frame. The user selects points upon the screen of a 

 video monitor using a video cursor controlled by a JOYSTICK. A synthetic 

 video signal representing a tiny bright dot is sent to the Bugwatcher which, in 

 turn, sends digitized video information to the computer. Because averaging 

 algorithms are employed, this method affords higher spatial resolution than 

 does fully automated input: each coordinate in the resultant data structure 

 may have 8-9 significant bits in comparison to the 7-8 bits of the normally 

 digitized input data. 



Input of video data to the computer effects a mapping of the image as seen 

 upon a television screen onto a two dimensional representational space. 

 Distances wdthin this space ("Bugspace") are measured in arbitrary internal 

 units (or "Bugwatcher units") and, therefore, must be scaled. Using the LIVE 

 INPUT operator, the Bugwatcher processed image of a ruler (or any object of 

 known length)— recorded under the same conditions used in gathering 

 behavioral data-is displayed on the screen of a CRT terminal and two points 



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