info viz work
Mitja Hmeljak
SL Forager Mapping (2009)

Conversion and visualization tool for the analysis of foraging avatars' movements in controlled behavior studies in Second Life.
Developed as part of the collective behavior studies in Second Life project.
Implemented in C and Objective C, to GLUT and Cocoa APIs on Mac OS X, using custom OpenGL C/C++ libraries.
ImageMatcher3D (2006)

Visualization tool for comparison-based coding of object orientation from images taken from a head-mounted camera.
Developed at IU for Department of Psychology prof. Linda B. Smith and Alfredo Pereira.
ImageMatcher3D has been developed as part of the research presented in:
 • Alfredo F. Pereira, Karin H. James, Susan S. Jones, Linda B. Smith: Active Object Exploration in Toddlers and its Role in Visual Object Recognition (2008). In B. C. Love, K. McRae, & V. M. Sloutsky (Eds.), Proceedings of the 30th Annual Conference of the Cognitive Science Society (pp. 2410-2415). Austin, TX: Cognitive Science Society. (2008)

“The object orientation was coded from each extracted video frame using a custom-made program. This software allowed a human coder to compare side-by-side, an image taken from the camera to an image of a computer rendered model of the same object (see Figure 5). The coder could rotate the 3D model such that the viewing angle matched that of the static image from the video. The coding software captured the orientation of the 3D model using Euler angles; these specified the necessary rotation to achieve that orientation.”

Implemented in Objective C and Cocoa for Mac OS X, using custom OpenGL C/C++ libraries.

Luria-Delbrueck tool (2004)

Visualization tool for estimating the mutation rate of bacteria (Luria-Delbrueck model), Java version.
Currently maintained at AVL, jointly developed at IU by Biology (prof.Patricia L. Foster) and Computer Science (prof.Andrew J. Hanson) in collaboration with AVL.
Development of the Java version included:
   • UML Use Case analysis 
   • UI mockups, several customer validation iterations 
   • M-V-C design 
   • reverse-analysis of previous releases (Qt/C++/OpenGL code)
  Implemented in Java using OpenGL-like libraries (jGL for minimal client-side requirements, JOGL for higher performance).
Matrix algorithm visual analysis (2002)

Real-time visualization tool of matrix-multiplication algorithms.
While performance comparison and caching effectiveness of matrix-multiplication algorithms was performed as batch-processing on clusters of identical machines, the real-time comparison of data access was enabled by this 3D interface to competing algorithms.
Written in C and OpenGL at IU Computer Science (prof.Paul Purdom).

Development included:  
   • design of hue- and size-coded qualitative representations of matrix data 
   • insertion of data visualization hooks in matrix processing code (no-skip visualization) 
   • multithreading for real-time version 

Active World Mapper (2001)

Interactive map tool, standalone applet version (2001 release).
Developed with Katy Böner as part of the Activeworlds-based iUni collaborative information universe, maintained by SLIS and AVL.

Analysis and visualization of spatial and temporal distribution of user interaction data collected in 3D virtual worlds. The Active World Mapper tool reads topology and propdump files and generates a 2D clickable map of the world's layout, with interactive links both to related web sites as well as to 3D locations within the virtual world. Property and buildings on virtual real estate are color coded based on development history.
Active World Mapper has been developed as part of the research presented in:
 • Katy Börner, Shashikant Penumarthy, Bonnie Jean DeVarco, Carol Kerney: Visualizing Social Patterns in Virtual Environments on a Local and Global Scale (2003). In Digital Cities III, Information Technologies for Social Capital: Cross-cultural Perspectives. Third International Digital Cities Workshop, Amsterdam, The Netherlands, September 18-19, 2003. Revised Selected Papers (pp. 325-340). Springer Berlin / Heidelberg. (2005)  
“Mitja Hmeljak, Alan Lin, Gyeongja Jun Lee, William R. Hazelwood, Sy-Miaw Lin, and Min Xiao who have been involved in the implementation and evaluation of the social visualization tool kit.”

Original version implemented client-side in Java for self-contained browser functionality, which analyzes data gathered at the Activeworlds server. The second release in 2002 moved data analysis parts server-side. Several generated world maps are still available online.
Designed and implemented: 
   • color-coding which combines the history of virtual property development with mutual topology representation 
   • actual display-based selection avoiding inverse projection, for pixel-accurate clickable map 
   • direct interaction with the Activeworlds browser as embedded applet 
  Mitja Hmeljak 2009