Custom/Complex
Visualisation Modes
The complex data
visualisation tool contains a number of custom display modes that can
be used to visualize different types of data within the rview volume
display environment: The custom display menu can be accessed from the
View layout menu:
Which provides the following control menu (V8.198):
MRI Volume Change
These modes display two images (reference and image A) and a
third (floating image B) volume change map (scalar) overlayed onto the
reference image.
Vector Fields
The vector field displays options are intended to allow the display of
a vector
dataset overlayed onto a scalar image. Load the conventional scalar
image as the Reference image, and floating Image A should be loaded
with a 4D dataset with 3+ frames in the 4th dimension (in analyze or
gipl format). It is assumed that each value in the first three frames
of this 4D image contain displacement vectors, each voxel holding x,y,z
displacements (in that order) in voxel units scaled by a factor.
Usually these are stored as integers using some scaling factor (say
100). The scaling factor can be set interactively using the max and min
values of the Colour Tool, to
create a suitable visualization of the vector field. Thus, if the data
in floating image A contains physical displacement vectors in units of
(voxel units)*100, they can be displayed accurately over the underlying
image data by setting the max and min to be 100 units apart (eg Min=0,
Max=100). This will display displacement vectors of the correct
physical length over the images. To amplify small displacements it is
often useful to select a narrower range (say 50) to scale the
displacements up by a factor of 2. This is useful for small
displacements but can produce displays that artifactually appear to be
'folded' with one vector mapping over another, depending on the regular
spacing of the vectors (see below).
The basic display (A+B mono) simply shows line vectors at a regular set
of points in each plane.The 3D vectors are projected onto the display
planes in each window:
The spacing of these lines can be set manually by using the 'Vector
Spacing' setting in the custom visualization tool:
This sets the spacing in mm of the regular separation of vectors on the
current display:
As with all rview displays the display scale can be altered using the zoom keys and the spacing remains fixed in
mm units:
The option "A+B direction Colrs" colour codes the vectors based on
their direction in the plane of the given display:
The option "Vec. Field + Grid" shows both the vector field and a
grid deformed using the same scale factor:
:
