My goal in this project is to provide an immersive free-form surface modeling environment using 3D relief sculpturing as the only primitive. Interaction will be based on a standard 2D visual display and an ordinary 2D mouse/keyboard combination (perhaps even a graphics tablet). The user will have the opportunity to work with the 2D image that creates the sculpture or work directly with the 3D mesh; both models are kept synchronized. The project has several aspects: 3D navigation, 3D object manipulation and interaction, and 2D image-based interaction.

The project is divided into the following major categories:

• 3D Navigation and Object Manipulation Using the Mouse: the primary difficulty will be in obtaining general enough navigation and surface manipulation controls that feel natural to the user. The model or surface must feel as though it is properly attached to the mouse pointer and the speed of navigation must feel natural at all scales. The interface must allow for "outside looking-in" kinds of navigation capabilities as well as immersed views; the user must be able to walk on the surface of the model.
• Image-to-Geometry Conversion: We must provide the user with various ways of creating the terrain mesh from the given or current image. This not only includes the mapping of the height from various values (brightness, red, green, blue, etc.), but also the color mappings (do not necessarily have to correspond to heights) and the overall shape of the relief sculpture (not necessarily on a plane).
• Image Editing: We must provide the user with a rich set of "brushes" to interact with the 2D image in creating the sculpture.
• Interactive 3D Mesh Editing: the user must be allowed to change the mesh directly rather than through the image. A fundamental experiment is to see if the user will take advantage of both methods of interaction: some things are easier to edit through the 2D image, other things are easier through the mesh directly in 3D.
• Alternative Forms of Input and Interaction: we could possibly provide the user with interaction through a graphics tablet (pen computing) or through a head-mounted display and hand tracker.
• Relief Sculpturing System Layout and Design: the encompasses the overall layout of the program including its interface and the interaction of the various parts (the other categories).

The progress is to proceed as follows:

1. Finish the OpenGL based viewer. This will provide the basic framework in which to work. I will provide basic navigation routines that I will refine throughout the course of the project.
2. Generalize the image-to-mesh process. I plan to provide many different meshing strategies from a given 24-bit heightmap.
3. Integrate the 2D image with the 3D viewer. Provide an interface to both.
4. Add some basic image editing features for the 2D view. The user will be allowed to create simple height maps directly through some simple tools or by loading in an image. Various adjustable parameters will be provided for deciding the height values. An interface for all of this must be implemented in the form of some type of toolbar.
5. Provide mappings of the relief sculpture into various shapes (spheres, cylinders, tori, mirrored surface, etc.).
6. Implement basic 3D mesh editing. At first the user will be able to select and move control points in the mesh in a very limited fashion; the image will be updated accordingly.
7. Provide additional navigation ability. Allow the user to walk on the surface of the sculpture without passing through it.
8. Experiment with fancier mesh generation alternatives: NURBS, etc.
9. Experiment with alternative image processing and filtering techniques.
10. Try alternative forms of input and interaction: graphics tablet and head-mounted display.
11. Add animation recording and playback capabilities not only for the camera, but for the sculpture generation.

What will we have to show for it?

1. "super-viewer" of triangle-based models complete with a wide-range of navigation and object manipulation routines, path recording and playback, and a screen-capturing "snapshot" utility. Perhaps reading of NURBS surfaces will also be included. The viewer will definitely support mouse and keyboard input, but perhaps also input from the "JoyBox" and the head-mounted display and "Pythons".
2. fast method for creating sophisticated free-form surfaces (sculptures) in an intuitive manner.
3. sophisticated integration of 2D and 3D manipulations of a 3D model that utilizes geometric and image-based methods.
4. create a complete, new, and fairly general modeling program for a wide-range of free-form surfaces that includes: relief sculptures; lathed objects; terrains and heightfields; spherical, cylindrical, or toroidal terrain mappings; and CSG sculptures.

• How to Turn Right, Ken Shoemake, SIGGRAPH '91 Course Notes.
• Animating Rotation with Quaternion Curves, Ken Shoemake, SIGGRAPH '85, Vol 19, No. 3.
• Quaternion Calculus for Animation, Ken Shoemake, SIGGRAPH '91 Course Notes.
• ARCBALL: A User Interface for Specifying Three-Dimensional Orientation using a Mouse, Ken Shoemake, SIGGRAPH '91 Course Notes.
• Polar Decomposition for Rotation Extraction, Ken Shoemake, SIGGRAPH '91 Course Notes.