get.plane {espadon}  R Documentation 
The get.plane
function extracts a plane from a "volume"
class object.
get.plane(
vol,
origin = c(0, 0, 0),
plane.orientation = c(1, 0, 0, 0, 1, 0),
alias = "plane.n",
xgrid = NULL,
ygrid = NULL,
interpolate = TRUE
)
vol 
"volume" class object. 
origin 
Vector of x, y, z coordinates, representing the origin of the
plane to extract. If 
plane.orientation 
Vector orientation of the plane in the 
alias 

xgrid 
Vector, representing the grid of the plane abscissa. See note. 
ygrid 
Vector, representing the grid of the plane ordinates. See note.
If 
interpolate 
Boolean, default to 
Returns a "volume" class object, containing only a single plane,
at k = 0
, in the same frame of reference as vol
.
This returned object has 2 new fields local.xgrid
, and local.ygrid
,
representing the local grids of the abscissa (columns) and ordinate (rows)
of the plane.
Returns NULL
if plane doesn't exist.
Determination of axes :
the xaxis has plane.orientation[1:3]
as unit vector.
the yaxis has plane.orientation[4:6]
as unit vector.
If xgrid
is not NULL, origin + x.grid * plane.orientation[1:3]
are the coordinates of the points on the x axis.
If ygrid
is not NULL, origin + y.grid * plane.orientation[4:6]
are the coordinates of the points on the y axis.
If xgrid
or ygrid
are NULL, they are determined to represent
as closely as possible the initial volume in the required cut.
# loading of toypatient objects (decrease dxyz for better result)
step < 4
patient < toy.load.patient (modality = "mr", dxyz = rep (step, 3))
MR < patient$mr[[1]]
# midvolume point
mid.point < apply (get.extreme.pt (MR),1,mean)
plane < get.plane (MR, origin = mid.point, interpolate = TRUE)
display.kplane (plane, interpolate = FALSE)
plane < get.plane (MR, origin = mid.point, xgrid = seq (50, 50, 1),
ygrid = seq (50, 50, 1), interpolate = TRUE)
display.kplane (plane, interpolate = FALSE)
# 3 points on the inclined plane
pts < t ((MR$xyz.from.ijk %*% MR$cube.idx) [1:3 , c (1, 2, 7)])
orientation < orientation.create (A = pts[1,], B = pts[2,], C = pts[3,])
origin < apply (pts, 2, mean)
plane < get.plane (MR, origin = origin,
plane.orientation = orientation, interpolate = TRUE)
display.kplane (plane, interpolate = FALSE)
orientation < orientation.create (A = c (0, 0, 0) , B = c (1, 1, 0),
C = c (1, 1, 0))
plane < get.plane (MR, origin = origin,
plane.orientation = orientation, interpolate = TRUE)
display.kplane (plane, interpolate = FALSE)