This paper describes 'Quick-sketch', a 2D and 3D modelling tool for pe
n-based computers. Users of this system define a model by simple pen s
trokes, drawn directly on the screen of a pen-based PC. Exact shapes a
nd geometric relationships are interpreted from the sketch. The system
can also be used to sketch 3D solid objects and B-spline surfaces. Th
ese objects may be refined by defining 2D and 3D geometric constraints
. A novel graph-based constraint solver is used to establish the geome
tric relationships, or to maintain them when manipulating the objects
interactively. The approach presented here is a first step towards a c
onceptual design system. Quick-sketch can be used as a hand sketching
front-end to more sophisticated modelling, rendering or animation syst
ems. Copyright (C) 1996 Elsevier Science Ltd