vtkPicker tolerance inaccurate
This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
vtkPicker's tolerance isn't really a fraction of the window size. A specified 1% screen tolerance in some cases can actually result in a 50% screen tolerance which makes it very inaccurate and unusable. This occurs more frequently when trying to pick small features on a large dataset.
See attached script for an example. The camera position and the geometry (approximately unit sized) remain fixed relative to each other. The script adjusts the focal point to be near and far and demonstrates the incorrect scaling of the pick tolerance.
I think its a flaw for vtkPicker to assume it can scale the tolerance once and apply that scale through all datasets in the session. There's also the possible issue of one dataset with a large span in the camera's Z direction, where the tolerance at one end shouldn't be the same as the tolerance at the other end.
This is probably not an issue with parallel projection.