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STRAT: A Sketched-Truss Recognition and Analysis Tool. VLC Workshop on Sketch Computing September 5, 2008 – Boston, Massachusetts. Background | Motivation | Demonstration | Recognition | Analysis | Conclusions. Engineers use simplified models to work with physical systems.
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STRAT: A Sketched-Truss Recognition and Analysis Tool VLC Workshop on Sketch Computing September 5, 2008 – Boston, Massachusetts
Background| Motivation | Demonstration | Recognition | Analysis | Conclusions Engineers use simplified models to work with physical systems...
Background| Motivation | Demonstration | Recognition | Analysis | Conclusions One basic modeling element is the pin-connected truss… ● Slender structural members that have zero mass●Members are all interconnected by joints ●Triangular sub-units for strength and stability
Background| Motivation | Demonstration | Recognition | Analysis | Conclusions There are several ways to solve truss problems – the standard approach… ● Set up a system of linear equations to solve●Determine the reaction forces at each support ●Determine whether each member is in T or C
Background| Motivation | Demonstration | Recognition | Analysis | Conclusions Solving truss problems “by hand” is not something engineers really do… ● Mathematics involved are not hard but tedious●CAD programs help but are costly (time and $) ●More intuitive ways to solve truss problems?
Background | Motivation| Demonstration | Recognition | Analysis | Conclusions Sketch Recognition provides a natural interface for solving truss problems…
Background | Motivation| Demonstration | Recognition | Analysis | Conclusions This is what we would like to do…
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions There are three phases of evaluation in our user study… 5 kips 12 12 12 1 kip 2 kips 10 10 10 10 10
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions There does exist a noticeable degree of variability among users…
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions Some previous related work… T.C. Hutchinson, R. Kuester, and M.E. Phair, “Sketching finite-element models within a unified two-dimensional framework,” Journal of Computing in Civil Engineering, Vol. 21, No. 3, May 2007. T.F. Stahovich, “SketchIT: a sketch interpretation tool for conceptual mechanical design,” Massachusetts Institute of Technology Artificial Intelligence Laboratory Technical Report No. 1573, March 2002. I.E. Sutherland, “Sketchpad: a man-machine graphical communication system,” In 25 Years of DAC: Papers on Twenty-Five Years of Electronic Design Automation, pp. 507-524, 1988.
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions The STRAT framework consists of two separate processing layers… Sketched-Truss Recognition Parsing of Complex Strokes Low-Level Recognition Recognized Associations Sketched-Truss Analysis Valuing of Truss Elements Assembly of Equilibrium Equations Solution of Equilibrium Equations
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions The sketch recognition phase consists of three separate steps… Recognized Associations Low-Level Recognition Parsing of Complex Strokes
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions Low-level recognition…simple lines and circles identified first…
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions Parsing of complex strokes…objects not recognized as simple lines or circles… RawStrokeObjectArray --------------------------------------- RawStrokeID Type (Line, Circle) BeginPointX BeginPointY EndPointX EndPointY Size
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions Recognized associations…if lines are members, create and assign nodes… 0 RawStrokeObjectArray --------------------------------------- RawStrokeID Type (Line, Circle) BeginPointX BeginPointY EndPointX EndPointY Size PercentOfMax BeginNode EndNode 1
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions The truss analysis phase also consists of three separate steps… Equation Solving FAC T Equation Assembly FAB RAy Element Valuing 12 12 12
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions Element valuing…currently we type in the values of the member lengths and external forces… But, handwriting is on the way…
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions Equation assembly…sum of forces are created for each node…
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions Equation solving…equation matrix is assembled, simply invert Ax = b…
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions Today we have discussed… ● The basics of truss analysis for engineers● Sketch recognition can be used as an interface to solve truss problems ● Variability exists among users ● More user data is needed to fully resolve
Background | Motivation | Demonstration | Recognition | Analysis | Conclusions What we plan to do next… ● Gather handwriting data for Phase III● Work on enhancing low-level recognition to capture maximum user variability ● Work on complex stroke parsing ● Integration with other applications
STRAT: A Sketched-Truss Recognition and Analysis Tool VLC Workshop on Sketch Computing September 5, 2008 – Boston, Massachusetts
