Abstract
We introduce OpenEyeSim 2.0, a detailed model of the biomechanics of human extraocular eye muscles and retinal image formation. Like its predecessor OpenEyeSim, it features realistic muscle paths, muscle pulleys, and muscle dynamics. In addition, OpenEyeSim 2.0 incorporates an efficient approximation of retinal image formation including accommodation control, depth-of-field effects, longitudinal chromatic aberration, and contrast sensitivity. Compared to ray tracing, our rendering process is kept simple and efficient, thereby facilitating studies on human vision development with large numbers of simulation steps. This makes OpenEyeSim 2.0 a versatile platform for developing computational models of the joint learning of visual representations and eye movement and accommodation control in the full perception action cycle. To simulate accommodation control and depth-of-field effects during retinal image formation, we use a simple but computationally efficient lens model. The model simulates different accommodation states (focal point, pupil aperture) by using a custom shader during the rendering process. Different levels of blur are applied pixel-wise based on an object's distance to the focal point and lens parameters. Longitudinal chromatic aberration is thought to play an important role in accommodation control and its development. OpenEyeSim 2.0 efficiently approximates chromatic aberration by an additional custom shader which applies different color manipulations during rendering of the three RGB color channels. As an additional component, OpenEyeSim 2.0 allows the simulation of different contrast sensitivity functions as measured in children from 1 to 8 months of age to study the effects of contrast sensitivity on visual development. To the best of our knowledge, OpenEyeSim 2.0 is the first simulator to combine realistic extra-ocular muscle dynamics with a simplified yet plausible model of retinal image formation including accommodation control, depth-of-field rendering, and chromatic aberration effects.