Summary form only given. In recent years, large displays have become increasingly popular. Several notable examples are sharing visualized large size of data, smart office, digital signage, interactive public art, and architectural exterior displays. These systems consist of both software and real space components. For instance, interactive digital signage likely utilizes software, cameras, sensors, projectors, speakers, PCs, and real spaces: room for exhibition, urban building for projection. In order to make these systems work correctly or effectively, developers are required to configure software and real space components at the same time. While integrated development environments (IDE) of graphic design and software design have become popular like as Adobe Flash or Apple Interface Builder, we don't have an appropriate IDE of space design and software design. We are currently developing such an IDE, named City Compiler, which simulates how an interactive system made with processing runs in the 3D virtual world modeled with Google SketchUp. City Compiler facilitates the design of interactive systems concerning the choice of sensors, actuators and their placement in the 3D world, including the assessment of their range of sensitivity and effect, e.g. the visibility of a display.