CA2328794A1 - Computational technique for inversion of a detail-in-context data representation - Google Patents

Claims (3)

1) Within a detail-in-context data presentation, the use of the distortion process or distortion function that produced the data presentation within an iterative technique for computing the inverse of the distortion.

2) The specific iterative technique using the following series of steps, to compute the inverse mapping from one or more points in a distorted (detail-in-context) data presentation back to the original undistorted original data space. Referring to figure 1, the point X is the desired point in the distorted data space which we wish to locate in the undistorted data space, i) The first approximation point P o is defined by the intersection point in the basal plane of the line through V and X.
ii) Point P o is displaced onto the distorted surface by application of D3.
The resultant point on the distortion function is P o D.
iii) The point P o D is projected on the line V-X as shown to locate P o P the closest point to P o D on V-X. P o P is then projected onto the basal plane in the opposite direction to that of the displacement due to the distortion, to produce the next approximation P i.
iv) Successive approximations P i for i>1 are then computed as follows. D3 is applied to Pi, and the process is repeated until sufficient accuracy is reached, such that ¦D3(P i) - X¦<.delta. where .delta. is an acceptable tolerance which is application dependent.

3) The use of the techniques described in 1) and 2) to accurately position a new focal region in a detail-in-context data presentation.

References Cited 1. M. S. T. Carpendale, A Framework for Elastic Presentation Space, Ph.D.
Thesis, Simon Fraser University, Burnaby, BC, Canada 1992