Difference between revisions of "Slicer3:Coordinates"
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* image data in a volume is laid out in memory in the same order as it is read from disk. That is, the "infamous VTK Y-flip" is ''not'' applied. | * image data in a volume is laid out in memory in the same order as it is read from disk. That is, the "infamous VTK Y-flip" is ''not'' applied. | ||
| + | * the reader for each file type is required to provide the IJKToRAS mapping. | ||
Revision as of 17:48, 20 July 2007
Home < Slicer3:CoordinatesCoordinate Definitions
This page describes the coordinate system assumptions for Slicer3
Volumes
IJK refers to voxel index coordinates.
RAS refers to Right-Anterior-Superior subject-referenced coordinates.
Each volume includes a transformation to go from voxel indices (IJK) to world (RAS). This is obtained with the vtkMRMLVolumeNode::GetRASToIJKMatrix(vtkMatrix4x4).
Models
Model vertices are expressed in millimeters, in RAS space.
Fiducials
Fiducial points are expressed in millimeters, in RAS space.
Transforms
All transforms at RAS to RAS transforms.
Notes
- image data in a volume is laid out in memory in the same order as it is read from disk. That is, the "infamous VTK Y-flip" is not applied.
- the reader for each file type is required to provide the IJKToRAS mapping.
