ieegio (version 0.0.9)

new_space: Define a coordinate space

Description

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, ...)

Value

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

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

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)

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