The process of captioning the results of computer graphics and visualization in 3-D CAD begins with the specification of the DotsPlus proposed standard for mathematical Braille typesetting.
The DotsPlus standard currently includes four fonts: 6-dot standard, 6-dot symbols, 8-dot standard and 8-dot symbols. The specification of each font includes an ASCII text description.
The formatted input ASCII text file contains lines of the form:
34 'dquote' g_height = 8 g_width = 5 c_height = 8 c_width = 5 bline = 0 xxxxx xxxxx xxxxx x0x0x x0x0x x0x0x xxxxx xxxxxThe Braille font glyph for the character 'double-quote' is described by a block of ASCII text with an 'x' indicating empty space and a '0' indicating a physical 'Dot'. There is an implied vertical and horizontal pitch per 'Dot' address of 0.1 inch.
The fromDotsPicTxt program reads the ASCII font description file and, for each character, translates an instance of a single, STL-buildable 'Dot' geometric mesh object to the specified X-Y address.
The meshes for each character glyph are grouped and accessed by the name of the character. The fromDotsPicTxt program outputs the meshes for the entire font into a single Open Inventor file.
KernIV then reads a line of ASCII text, typed into an X TextField widget in the GUI and for each character, it translates an instance of the corresponding font glyph to the next position on the line of output 3D geometry. It will be necessary to parse compositional tags to correctly position subscripts, superscripts, fractions and other mathematical formatting.
Square-root symbols, brackets enclosing fractions and other non-text raised lines will need to be generated procedurally and may need to be tightly integrated with the facility for applying captions to free-form surfaces.
The intent of tactile captioning in visual computing is to re-integrate with the physical model the symbolic statement of the abstraction it represents. This means applying text to a 3-D computer graphic surface mesh such that it becomes a unified CAD model which can be constructed via rapid prototyping, rapid tooling and/or rapid manufacturing.
Positioning Braille characters on a free-form surface is a painstaking task: Each dot must be positioned precisely for accurate readability and the text must flow across the surface in a sensible manner. It is not feasible to do this manually. The line of text must be positioned across the surface as a unit.
The line of Braille text is translated into the "local coordinate space" of a parametric surface using the ParaMeshMap program.
Certain complications arise when attempting to pass objects from scientific visualization to rapid prototyping and manufacturing.
Once the buildable CAD model is joined with its set of captions, it is converted to the STL file format standard for the rapid prototyping industry and handed off for building.
Creating Tactile Captions in Three-Dimensional Computer-Aided Design Proceedings of the California State University at Northridge Technology and Persons With Disabilities Conference 2004.
Tactile Mathematics, Published in: "Mathematics and Art", Claude P. Bruter, Ed.; 2002: Springer-Verlag, Berlin. ISBN 3-540-43422-4. Proceedings of the International Colloquium on Art and Mathematics, Maubeuge, France, 20-22 September, 2000.
Stewart Dickson, Visualization Research Programmer Integrated Systems Laboratory Room 4355 Beckman Institute University of Illinois at Urbana-Champaign 405 North Mathews Avenue Urbana, IL 61801 USA