| persp.im {spatstat} | R Documentation |
Displays a perspective plot of a pixel image.
## S3 method for class 'im' persp(x, ..., colmap=NULL, colin=x, apron=FALSE)
x |
The pixel image to be plotted as a surface.
An object of class |
... |
Extra arguments passed to |
colmap |
Optional data controlling the colour map. See Details. |
colin |
Optional. Colour input. Another pixel image (of the same dimensions
as |
apron |
Logical. If |
This is the persp method for the class "im".
The pixel image x must have real or integer values.
These values are treated as heights of a surface, and the
surface is displayed as a perspective plot on the current plot device,
using equal scales on the x and y axes.
The optional argument colmap gives an easy way to display
different altitudes in different colours (if this is what you
want).
If colmap is a colour map (object of class "colourmap",
created by the function colourmap)
then this colour map will be used to associate
altitudes with colours.
If colmap is a character vector, then the range of
altitudes in the perspective plot will be divided into
length(colmap) intervals, and those parts of the surface
which lie in a particular altitude range will be assigned
the corresponding colour from colmap.
If colmap is a list with entries breaks and col,
then colmap$breaks determines the breakpoints of the altitude
intervals, and colmap$col provides the corresponding colours.
Alternatively, if the argument colin (colour input) is present,
then the colour map colmap will be applied to
the pixel values of colin instead of the pixel values of
x. The result is a perspective view of a surface with
heights determined by x and colours determined by colin
(mapped by colmap).
If apron=TRUE, vertical surface is drawn around the boundary
of the perspective plot, so that the terrain appears to have been
cut out of a solid material. If colour data were supplied, then
the apron is coloured light grey.
Graphical parameters controlling the perspective plot
are passed through the ... arguments
directly to the function persp.default.
See the examples in persp.default or in
demo(persp).
The vertical scale is controlled by the argument expand:
setting expand=1 will interpret the pixel values as being in
the same units as the spatial coordinates x and y and
represent them at the same scale.
(invisibly) the 3D transformation matrix
returned by persp.default,
together with an attribute "expand" which gives the
relative scale of the z coordinate.
Adrian Baddeley Adrian.Baddeley@uwa.edu.au http://www.maths.uwa.edu.au/~adrian/ Rolf Turner r.turner@auckland.ac.nz and Ege Rubak rubak@math.aau.dk
im.object,
plot.im,
contour.im
# an image
Z <- setcov(owin())
persp(Z, colmap=terrain.colors(128))
co <- colourmap(range=c(0,1), col=rainbow(128))
persp(Z, colmap=co, axes=FALSE, shade=0.3)
## Terrain elevation
persp(bei.extra$elev, colmap=terrain.colors(128),
apron=TRUE, theta=-30, phi=20,
zlab="Elevation", main="", ticktype="detailed",
expand=6)