Proposals:Refactoring Index Point Coordinate System

Overview

The conversion between physical points and indices is not consistent in all places in the toolkit.

The following cases must be considered

• Interpolators
• Registration
• Transforms
• DICOM
• Conversion between ITK and VTK
• Backwards compatibility
• Template programming for more efficient conversions

Review of Current Status

Image Class

The image class considers that the location of a pixel is at the physical coordinates of the center of the pixel.

NOTE: The original file for this diagram can be found in
InsightDocuments/SoftwareGuide/Art/ImageOriginAndSpacing.fig
http://www.itk.org/cgi-bin/viewcvs.cgi/SoftwareGuide/Art/ImageOriginAndSpacing.fig?root=InsightDocuments&view=log

NOTE #2: The diagrams below are not quite correct in that they show the origin as being in the lower left corner of the image where the origin is really in the upper left hand corner.

PNG Diagram

SVG Diagram

Interpolators

Interpolators are used in the Registration Framework and in the Resampling filters.

Refactoring Proposal

Patches

• Patches are available in the Bug Tracker
  • http://public.kitware.com/Bug/view.php?id=6558

Discussion

• http://www.itk.org/pipermail/insight-users/2009-May/030219.html