4.6 Clock

The clock transformation is an angular fisheye transformation which allows a selected azimuthal region to be shown in detail while still displaying the full 360°. It is only available in the Y/X projection (5.1 Y/X Projection).

Under a clock transformation about an axis φ0, φ transforms to φnew with:

φnew = φ0 + ((π/d)×Δφ) / ((π/d)+π-|Δφ|)

where d is the clock distortion factor and Δφ=φ-φ0. The clock transformation does not change ρ. The values of Xnew, Ynew are calculated from ρ and φnew.

Applying the Clock Transformation

The clock interaction is selected for the current canvas pad by clicking on the Clock tab of the interaction control (3.1.3 Interaction Control) in the Control Window. The label of the tab contains a toggle to activate and deactivate the interaction. Upon activation the distortion factor d is modified by clicking on a point at a selected opening angle with respect to the φ0 direction and dragging it to a larger or smaller opening angle.

When the clock interaction is selected, a white line appears over the picture representing the selected φ0 direction around which to perform the angular fisheye. This φ axis may be rotated by dragging it with the mouse.