Comparable to model making, the simulation also differentiates between the working model and the presentation model. While the working model simplifies the design process in that it provides rough, sketched variants, the presentation model includes elaborate details. In lighting design, sketches, digital drawings and photo realistic representations are quick visualisation methods. For further examination this is followed by general light simulation, omitting exact details of materials or luminaires. In a subsequent step, the simulation is improved by including realistic surfaces and specific luminaires with accurate photometrics for detailed planning and presentation purposes. .