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Define a coordinate space

Source: R/as_ieegio_space.R
new_space.Rd

Creates an object representing a coordinate space/reference frame used in medical imaging. The orientation defines the anatomical meaning of the coordinate axes.

Usage

new_space(name = "", orientation = ORIENTATION_CODES, dimension = 3, ...)

Arguments

name

character string identifying the coordinate space (e.g., "T1w", "MNI152NLin2009cAsym", "scanner"); default is "", a wildcard that indicates arbitrary space

orientation

character string specifying the axis orientation convention. Common orientations in brain imaging:

  • "RAS": Right-Anterior-Superior (FreeSurfer, NIfTI default)

  • "LAS": Left-Anterior-Superior

  • "LPS": Left-Posterior-Superior (DICOM, ANTs, ITK)

  • "RPS": Right-Posterior-Superior

  • "LPI": Left-Posterior-Inferior

  • "RPI": Right-Posterior-Inferior

  • "LAI": Left-Anterior-Inferior

  • "RAI": Right-Anterior-Inferior

dimension

integer dimension of the space (typically 3 for 3D imaging)

...

additional attributes to attach to the space object

Value

An S3 object of class "ieegio_space" with attributes orientation and dimension

Details

Orientation codes use three letters to define the positive direction of the x, y, and z axes respectively:

  • First letter (x-axis): Left or Right

  • Second letter (y-axis): Anterior or Posterior

  • Third letter (z-axis): Superior or Inferior

For example, "RAS" means: +x points Right, +y points Anterior (toward face), +z points Superior (toward top of head).

Examples

# FreeSurfer/NIfTI convention
scanner_space <- new_space("scanner", orientation = "RAS")
print(scanner_space)
#> scanner (RAS)

# DICOM/ANTs convention
mni_space <- new_space("MNI152NLin2009cAsym", orientation = "LPS", dimension = 3)
format(mni_space)
#> [1] "MNI152NLin2009cAsym (LPS)"