<![CDATA[T4: Direct Modeling of Virtual Mockup]]>This task will design a new interactive modeling environment where procedural modeling techniques will be used to create more efficient operators than traditional CAD applications. The main research challenge is how we can take advantage of procedural modeling in an interactive environment based on body gesture and sketching without having to script or edit directly embedded shape grammars. Bolseiro BIM2 and PhD student Bruno Araujo (PhD thesis entitled Interactive Procedural Modeling in Semi-Immersive Environments) will conduct the main research of this task strongly related with its PhD. The task is divided into five subtasks.

Subtask 4.1: Constraint Based Sketching of 3D Models on Multitouch Displays
To make sketching as a usable modality to create rigorous buildings, we should offer to users the possibility to constrain its drawings and define precise measures. While sketch based interfaces has bet on fast and simple methods to construct geometry, it need to be scalable to create complex and precise 3D models such as buildings. The usage of constraints and the possibility to define measures will enable to overcome such issue. Sketching techniques needs to be researched to allow constraints in input drawings but also combining the information introduced with the current geometry of the scene to allow creating complex geometry.

Subtask 4.2: 3D Modeling Decomposition based Sketched Patterns and 3D Manipulation
Procedural Modeling and shape grammars are based on rules and on the underlying decomposition or structure of 3D models. To be able to include grammars, research needs to be conducted on pattern analysis and proportion or scale detection on sketched 3d models. This will allow structuring the 3D model and representing it internally not only as boundary representation but also as a grammar. The grammar description will enable high level editing operation of the model. Reusability of content
and exceptions on geometric structures are other challenges to be handled in this task.

Subtask 4.3: Gesture On and Above the Surface for High Level Editing
To perform high level editing of shape grammar based 3D models, interaction techniques should be researched to allow interacting with the 3D model using gestures and bimanual interaction. It is important to identify which part of the model should edited and the correct gestures to be used to specify changes such a resizing a building or adding windows to a given floor or even just moving on a meaningful way a door. Analyzing the way how designers create and modify physical mockups
can provide clues involving several users to define the most appropriate set of gestures.

Subtask 4.4: Interactive Creation and Edition of Virtual Mockups
This task will provide procedural modeling operators by interacting directly with the 3D generated content combining constrained based sketching inputs, procedural modeling and gestures inputs. Interaction techniques will be modeled on top of the procedural engine defined by Task 2 and provide a modeling environment supporting interactive modeling and direct manipulation of grammar elements on and above a tabletop display.

Subtask 4.5: Demonstrator for Design Review of Architectural Scenes
In order to demonstrate the most value of combining two hand interactions with procedural modeling in our mixed reality design environment, a demonstrator using a stereoscopic multitouch display will be developed for Design Review of Architectural Scene where the user can annotate and perform high level editing operation on a virtual mockup.

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