Michele Fiorentino - 2012-07-12

The parameters involved in the visualization of the text (text font, font, color, size, position, etc..) are too many from extensive tests. In an initial stage of the experiments design we needed to detect among all the possible parameters the most significant in a trial and error approach. For this reason we developed the application called HMD Testbed with the maximal flexibility in mind.

The HMD Testbed is written C++ using Qt library (trolltech) and has two main functions: the editor and the player. In the editor the user can edit interactively all the parameters of the text visualization. A simple GUI and a preview window show the results in real time on the monitor (view figure). If the HMD is connected on the second video port, the user can preview the visualization directly on the HMD, otherwise he can simulate the result with a selected background image (see figure).

A screenshot of the application editor GUI, with an image simulating the real background on a monitor

This allowed us to simulate different configuration using a library of 100 pictures taken from internet.(see figure).

A sample of the workshop images used in the preliminary design phase

When the user decided all the test configurations in term of font, size, text color and transparency, text background color and transparency, outline width, outline color and transparency, he can generate a specific number of random tests with it. The user can save the whole experiment in a file (file extension .templatetest). The second function of the application is to automate the execution of tests. Test is executed in the player mode: the configurations are first shuffled randomly and then displayed on the HMD. The player write in a text log file the input form the user, the time of response and the correctness of the answer. The simplicity of this platform allowed us run a large number of test. Currently the test is available al our website for free. In fact we are interested to During the test the second monitor, not seen by the subject of the test, display the performances and the progress bar and the top score. The score is added to motivate the user to maximize their performances during the tests

Player mode: the list of configurations in the center, progress bar in the lower left, and the user performances and top score.