Interactive visual editing of grammars for procedural architecture

Markus Lipp, Peter Wonka, Michael Wimmer
2008 ACM SIGGRAPH 2008 papers on - SIGGRAPH '08  
Figure 1 : Screenshots from our real-time editor for grammar-based procedural architecture. Left: Visual editing of grammar rules. Middle left: Direct dragging of the red ground-plan vertex and modifying the height with a slider creates the building on the middle right. While dragging, the building is updated instantly. Right: Editing is possible at multiple levels, here the high-level shell of a building is modified. Abstract We introduce a real-time interactive visual editing paradigm for
more » ... e grammars, allowing the creation of rulebases from scratch without text file editing. In previous work, shape-grammar based procedural techniques were successfully applied to the creation of architectural models. However, those methods are text based, and may therefore be difficult to use for artists with little computer science background. Therefore the goal was to enable a visual workflow combining the power of shape grammars with traditional modeling techniques. We extend previous shape grammar approaches by providing direct and persistent local control over the generated instances, avoiding the combinatorial explosion of grammar rules for modifications that should not affect all instances. The resulting visual editor is flexible: All elements of a complex state-of-the-art grammar can be created and modified visually. Direct Visual Editing While text-based production systems are very powerful, end users require a visual frontend to be able to use them productively. It is important to provide both a visual rule editor to create and modify the individual rules of the grammar and immediately see the consequences for the generated models, as well as a visual model editor which allows modifying the instances generated by the rule derivation process. Local Modifications Assume the artist wants to assign a different texture, different window width or different ornamentation rule to a specific window on a facade. In a current text-based procedural modeling system, the artist would have to write several new rules to identify the floor and column of the window and add the modification. In a visual editor, the desired workflow is that the artist simply selects the desired window and chooses a new texture, rule or window width. To make this happen, we need to solve the problem how to allow local modifications to variables, rule selection and geometry, without having to change the underlying grammar.
doi:10.1145/1399504.1360701 fatcat:6hqcpmwpqzgh7g76bjq63fy4t4