spatstat.geom (version 3.2-8)

perspPoints: Draw Points or Lines on a Surface Viewed in Perspective

Description

After a surface has been plotted in a perspective view using persp.im, these functions can be used to draw points or lines on the surface.

Usage

perspPoints(x, y=NULL, ..., Z, M, occluded=TRUE)
perspLines(x, y = NULL, ..., Z, M, occluded=TRUE)
perspSegments(x0, y0 = NULL, x1 = NULL, y1 = NULL, ..., Z, M, occluded=TRUE)
perspContour(Z, M, ...,
             nlevels=10, levels=pretty(range(Z), nlevels),
             occluded=TRUE)

Value

Same as the return value from

points

or segments.

Arguments

x,y

Spatial coordinates, acceptable to xy.coords, for the points or lines on the horizontal plane.

Z

Pixel image (object of class "im") specifying the surface heights.

M

Projection matrix returned from persp.im when Z was plotted.

...

Graphical arguments passed to points, lines or segments to control the drawing.

x0,y0,x1,y1

Spatial coordinates of the line segments, on the horizontal plane. Alternatively x0 can be a line segment pattern (object of class "psp") and y0,x1,y1 can be NULL.

nlevels

Number of contour levels

levels

Vector of heights of contours.

occluded

Logical value specifying whether parts of the surface can be obscured by other parts of the surface. See Details.

Author

Adrian Baddeley , Rolf Turner and Ege Rubak

Details

After a surface has been plotted in a perspective view, these functions can be used to draw points or lines on the surface.

The user should already have called persp.im to display the perspective view of the surface Z and to obtain the perspective matrix M by typing M <- persp(Z, ...). The points and lines will be drawn in their correct three-dimensional position according to the same perspective.

If occluded=TRUE (the default), then the surface is treated as if it were opaque. The code will draw only those points and lines which are visible from the viewer's standpoint, and not obscured by other parts of the surface lying closer to the viewer. The user should already have called persp.im in the form M <- persp(Z, visible=TRUE, ...) to compute the visibility information.

If occluded=FALSE, then the surface is treated as if it were transparent. All the specified points and lines will be drawn on the surface.

See Also

persp.im

Examples

  M <- persp(bei.extra$elev, colmap=terrain.colors(128),
             apron=TRUE, theta=-30, phi=20,
             zlab="Elevation", main="", 
             expand=6, visible=TRUE, shade=0.3)

  perspContour(bei.extra$elev, M=M, col="pink", nlevels=12)
  perspPoints(bei, Z=bei.extra$elev, M=M, pch=16, cex=0.3, col="chartreuse")