Nowadays almost everything is digital. Even testing new products can be done by simulating them digitally, also called virtual prototyping. This report describes research that is done to improve virtual prototyping at Philips Research. Two experiments have been performed with the aim to evaluate how image quality and realism are affected by the integrator, i.e. the method used to calculate the light at each point in the scene, and the time spent on the rendering process. The first experiment was conducted to evaluate whether a different integrator than an implementation of a standard path tracer might result in more realistic renderings. Mitsuba was used as render software and support integrators both based on path tracing and photon mapping. Two images of the same scene were simultaneously shown to 20 participants separately. The participants had to indicate which of the two they considered most realistic. They had to do this for different lighting conditions and with and without a reference to the real scene. The results showed that people preferred a photon based integrator over the path based integrators. The second experiment focused more on how material characteristics influence the rendering time. Renderings of a teapot with different materials and under different lighting conditions were created with Mitsuba and Indigo software. Participants had to compare a rendering to a reference rendering, which was part of a standard quality ruler, based on one type of material and light condition. As a consequence, they had to compare quality across different materials and lighting conditions. The results were widely spread across the 20 participants, mainly because comparing quality of different materials was a difficult task. The task became even more complicated because of the different kinds of noise generated by the different integrators. To overcome the issue found in the second experiment, a follow-up study was conducted. In this follow-up study the participants not only saw a stimulus and a ruler rendering but also the perfect versions of those two. The task was now to identify if the stimulus or the ruler rendering had the smallest difference with their perfect version. The results for the 4 participants that performed this follow-up study were less spread than those of the second experiment. Therefore the interface used in the follow-up study is considered to be useful for future experiments where comparisons across different materials are needed.