show3d-methods {dti}R Documentation

Methods for Function ‘show3d’ in Package ‘dti’

Description

The function provides 3D visualization of "dtiTensor" and "dtiIndices" objects using the "rgl"-package. Functionality of the rgl-package allows to rotate and zoom the displayed object.

Usage

  ## S4 method for signature 'dtiTensor':
  show3d(obj, nx=NULL, ny=NULL, nz=NULL, center=NULL, method=1, level=0, scale=.25, bgcolor="black", add=FALSE, subdivide=2, smooth=TRUE, maxobjects=729, ...)
  ## S4 method for signature 'dtiIndices':
  show3d(obj, index="FA", nx=NULL, ny=NULL, nz=NULL, center=NULL, method=1, level=0, bgcolor="black", add=FALSE, lwd=1, ...)

Arguments

obj An object of class dtiTensor or dtiIndices
nx Number of voxel in x-direction
ny Number of voxel in y-direction
nz Number of slices
center Vector of length 3 specifying the center of the data cube (class dtiTensor) or center of display (class dtiIndices)
method method==1 and method==2 specify two different color schemes for directional FA-maps.
level Minimal FA value of tensors.
scale Scale factor for the size of ellipsoids
bgcolor Backgroundcolor for rgl-display
add If true information is added to the current device, otherwise a new device is opened.
subdivide Level of subdivisions for meshing of ellipsoids, see package rgl.
smooth Use smooted surfaces, see package rgl.
maxobjects Maximal size of data cube (in voxel) to display
index Eiter "FA" for fractional anisotropy index or "GA" for geodesic anisotropy index.
lwd Line width to use.
... Additional parameters passed to function rgl.par from the rgl-package.

Value

The function returns the number of the current rgl-device.

Methods

obj = "ANY"
Returns a warning
obj = "dtiIndices"
Objects are visualized as a collection of line segments with location given by the voxel center, orientation and color determined by the main direction of inisotropy and length corresponding to either fractional or geodesic anisotropy as specified in index.

Displayed objects are restricted to voxel with an fractional (geodesic) anisotropy larger than level.

obj = "dtiTensor"
Ellipsoids are visualized at the voxel centers. Orientation and size correspond to the tensor values, color is determined by the main direction of anisotropy using the colorsceme specified with method. The fractional anisotropy value is coded as transparency. The value of maxobjects limits the size of datacube and may be increased on hardware with suitable graphics capabilities.

Displays can be closed using function rgl.close

Author(s)

Karsten Tabelow tabelow@wias-berlin.de
J"org Polzehl polzehl@wias-berlin.de

See Also

dtiIndices-methods, dti.smooth, dtiTensor, dtiIndices

Examples

  ## Not run: demo(dti_art)

[Package dti version 0.6-0 Index]