cwhmisc (version 2.1)

persp2: Central perspective from 3 to 2 dimensions along specified axis

Description

Transform 3-dimensional data by central perspective to plane coordinates.

Usage

persp2(d,axis,r)

Arguments

d

Data matrix, one row is one point (x,y,z).

axis

One of 1, 2, 3 to name axis of perspective.

r

The eye point lies at (axis = r, 0, 0).

Value

• The matrix d with column axis unchanged, the other two columns replaced by their perspective transformation.

Examples

par(mfrow=c(1,1))
  x <- c(0,5,NA,0,0,NA,0,0)
  y <- c(0,0,NA,0,6,NA,0,0)
  z <- c(0,0,NA,0,0,NA,0,4)
  d <- cbind(x,y,z)
  dr <- d %*% rotm(3,1,3,pi/5) %*% rotm(3,1,2,-pi/4) 
  D <- persp2(dr,1,2)
  dx <- D[1:2,]; dy <- D[4:5,]; dz <- D[7:8,]
  plot(0,xlim=range(D[!is.na(D[,2]),2])*1.3,ylim=range(D[!is.na(D[,3]),3])
         *1.3,type="n",xlab="",ylab="")
  lines(dx[,2],dx[,3],col="red")
  lines(dy[,2],dy[,3],col="green")
  lines(dz[,2],dz[,3],col="blue")