Scale bar using RGL

Question

is there a way I could get scale when I run a plot in RGL in R Studio for a point cloud?

I currently have a point cloud from a las file and when I plot the data it process with a different color corresponding to changing height in the point cloud. Is there a way to get a sale bar that shows the corresponding color in RGL?

Answer 1

Here's one way: divide the plot region into two parts, one for the plot, one for the scale. Plot your points in one region, then use bgplot3d() in the other region to plot a scale.

For example:

library(rgl)     # for the plot
library(plotrix) # for the scale

x <- rnorm(1000); y <- rnorm(1000); z <- seq(-3, 3, len=1000)
open3d(windowRect = c(10, 10, 500, 500))
layout3d(matrix(1:2, 1,2), c(0.8, 0.2), 1)
plot3d(x, y, z, col=rainbow(1000)[rank(z)])
next3d()
bgplot3d({
  plot.new()
  color.legend(0.1, 0.1, 0.9, 0.9, 
               rect.col=rainbow(1000), 
               legend=(-3):3, gradient="y", cex = 1.5)
  })

This produces

One problem with this method of drawing a scale is that it is a bitmap drawing, so if you resize the plot, it will tend to look bad. If you want one that will scale itself, you might want to investigate the plot3Drgl package.