Picking

The ability to pick points in a multi-dimensional cube was part of the original Rickmovie program. The original design was limited in the respect that picks could not be differentiated. Therefore picking multiple surfaces required either erasing each individual pick or restarting. To allow multiple objects to picked I added a marker component to the stored picking information. The marker is a single text character that can be changed by bringing up the picking menu (hold down `c' and press the right mouse button). The TEXT field of the picking menu is used to set the active marker. Once the Change button on the picking menu is hit each new pick will be displayed with the new marker. Figure 1 demonstrates the concept. One object is marked with `b' the other with `a'. When the picks are written out, the mark character will also be written.

 

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Figure 1 An example picking multiple surfaces.

Another limitation of the original design was the inability to do auto picking. I added a couple rudimentary auto-picking features. The first is the ability to `snap' picks to similar locations (activated by holding down `b' and the right mouse button). To figure out the `snapped' location all the points within the currently viewed cube, with the active marker are sellected. A super trace is built by taking a region (arround a user-specified dependent axis) the selected point and summing. Cross correlation is then run to find the shift at each location that produces the highest correlation with the super-trace. A new super trace is then constructed from the new point locations. The process is repeated five times. The dependant axis and the search radius are both changeable through the picking menu.

In addition to the ability to snap points a simple auto picker is included. The auto-picker uses a basic region growing algorithm. It uses the simple dip and coherency calculation method of Claerbout (1992). Figure 2 demonstrates its use. In this case three points were seeded for the algorithm.

 

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Figure 2 The auto-picker in Ricksep. The `x' were seeded with 3 points.