Fig. 1. The components of LightGuider : (a) a 3D modeling view to place and modify luminaires, augmented with (b) a provenance tree, depicting several sequential modeling steps and parallel modeling branches, integrating information on the quality of the individual solutions, and providing guidance by pre-simulating and suggesting possible next steps to improve the design. A film-strip-like visualization (c) of screenshots helps to depict the evolution up to the currently selected state. A quality view (d) informs about the fulfillment level of the illumination constraints that need to be met, using bullet charts. Changing the weights of these constraints (e), and therefore, the lighting designer's focus, triggers an update of the provenance tree node visualizations (reflecting the weights of the constraints in the distribution of the treemap space). Moreover, the defined weights are also considered in the generation of new suggestions, which are tailored towards satisfying constraints with higher weights.Abstract-LightGuider is a novel guidance-based approach to interactive lighting design, which typically consists of interleaved 3D modeling operations and light transport simulations. Rather than having designers use a trial-and-error approach to match their illumination constraints and aesthetic goals, LightGuider supports the process by simulating potential next modeling steps that can deliver the most significant improvements. LightGuider takes predefined quality criteria and the current focus of the designer into account to visualize suggestions for lighting-design improvements via a specialized provenance tree. This provenance tree integrates snapshot visualizations of how well a design meets the given quality criteria weighted by the designer's preferences. This integration facilitates the analysis of quality improvements over the course of a modeling workflow as well as the comparison of alternative design solutions. We evaluate our approach with three lighting designers to illustrate its usefulness.