An infinite-resolution grid snapping technique based on fuzzy theory

Abstract

In ordinary CAD systems with pointing devices, users input geometric objects by inputting their feature points one by one through pointing and dragging operations. Thus, each of the feature points is snapped into place interactively, and the geometric objects are aligned on the specified grid as a result. In sketch-based CAD systems with pen input devices, users simply draw a freehand stroke that the system recognizes as a geometric object, and then the system must automatically snap all of the feature points to the grid by a batch process. In this case, it is not easy for the user to set up the grid resolution in advance, because the appropriate resolution changes according to the drawing. Therefore, a multi-resolution fuzzy grid snapping (MFGS) technique has been proposed. In MFGS, the appropriate snapping resolution is dynamically selected in a multi-resolution grid system according to the roughness of the drawing manner. However, the multiplicity of the grid resolutions in MFGS is limited to a finite number, and grid snapping outside this range of resolutions cannot be appropriately handled. In this paper, we propose infinite-resolution fuzzy grid snapping (IFGS), in which there is an infinite number of grid resolutions, and experimentally demonstrate that IFGS effectively resolves the problems of MFGS.