[R] rgl zooming to an arbitrary location

[Duncan Murdoch]

On 31/08/2014, 11:12 PM, Gareth Davies wrote:
> 
> I have been using rgl to view xyz point clouds containing topographic 
> data ( with around 10^5 - 10^6 points).
> 
> It's working well aside from one thing: I would like to be able to zoom 
> into an arbitrary part of the plot. However so far I could only figure 
> out how to zoom into the centre.
> 
> See the example below -- in this case, I cannot 'zoom-in' to anything 
> other than the central hill in the topography, whereas I would like to 
> be able to zoom to an arbitrary location.
> 
> Is there a way to get around this?

Yes, you can manually set the userMatrix transformation.  See ?par3d for
a discussion about how rgl figures out what to display.  See the example
in ?rgl.setMouseCallbacks for some code that does something like what
you want.

There are plans to make this a little simpler in the next major release,
but no definite release date.

Duncan Murdoch

> 
> ##########################################
> # EXAMPLE CODE
> ##########################################
> library(rgl)
> # Make up some topography
> x=runif(1e+06, min=0,max=1000)
> y=runif(1e+06, min=0,max=1000)
> # Elevation with 'hill' in the centre
> z=sin(x/50.)+cos(y/50.) + 30*exp(-((x-500)^2+(y-500)^2)*0.001)
> plot3d(x,y,z,col=z+3,aspect=FALSE)
> # Now try zooming [right mouse button]. I can only zoom into the central 
> hill, not elsewhere.
> 
> 
> Below are the details of my R Install
> 
>  > sessionInfo()
> R version 3.1.1 (2014-07-10)
> Platform: x86_64-unknown-linux-gnu (64-bit)
> 
> locale:
>   [1] LC_CTYPE=en_AU.UTF-8       LC_NUMERIC=C
>   [3] LC_TIME=en_AU.UTF-8        LC_COLLATE=en_AU.UTF-8
>   [5] LC_MONETARY=en_AU.UTF-8    LC_MESSAGES=en_AU.UTF-8
>   [7] LC_PAPER=en_AU.UTF-8       LC_NAME=C
>   [9] LC_ADDRESS=C               LC_TELEPHONE=C
> [11] LC_MEASUREMENT=en_AU.UTF-8 LC_IDENTIFICATION=C
> 
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods base
> 
> other attached packages:
>   [1] rgl_0.93.1098        unstructInterp_0.0-1 rgeos_0.3-6
>   [4] rgdal_0.8-16         sp_1.0-15            geometry_0.3-4
>   [7] magic_1.5-6          abind_1.4-0          SearchTrees_0.5.2
> [10] roxygen2_4.0.1
> 
> loaded via a namespace (and not attached):
> [1] digest_0.6.4    grid_3.1.1      lattice_0.20-29 Rcpp_0.11.2
> [5] stringr_0.6.2   tools_3.1.1
>  >
> 
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