4.5 Fisheye

If the calorimeters and the muon detectors are drawn in, e.g. the Y/X projection ( 5.1 Y/X Projection), the inner tracking chambers are so small that track recognition may suffer. This problem may be partially solved by applying a fisheye transformation, which allows a relative magnification of the inner chambers without increasing the outer radius. Besides, since the outer parts of the detector are in sight, tracks are still completely visible.

A fisheye transformation is available in most projections:

Applying the Fisheye Transformation

The fisheye interaction is selected for the current canvas pad by clicking on the Fisheye 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 fisheye and a box with the value of the distortion factor d. This value is modified by clicking the left mouse button and dragging the cursor over the picture. If the F modifier key is pressed while dragging, the data will not be updated, thus allowing for better response.

The Fisheye Pop-up Menu

The Fisheye Pop-up Menu can be accessed by right-clicking into the desired canvas pad. It contains the following set of utility operations: