parvezrana/pointcloudviewer

An OpenGL point cloud viewer for R able to handle several millions of points

This is a point cloud viewer for R. The first goal of this package is to be the backend to display point clouds in the lidR package in replacement of rgl (full support since lidR v1.4.0).

rgl is an awesome package but has some difficulties displaying large point clouds. The 'PointCloudViewer' package is able to display large point clouds consisting of several million points. So far I have tried it with over 30 million points and the display window remained fluid (smoothly pan, zoom and rotate).

Advantage of PointCloudViewer:

• can easily handle more than 20 million points while rgl can struggle displaying a tenth of that.
• has pan zoom rotate while rgl only has zoom rotate.
• is much more memory efficient. It allocates only a small amount of additional memory.

Drawbacks

• blocks the R session. If the viewer windows is open, you can't use R for anything else. You must close the viewer windows first (so no multiple plots).
• can only display point clouds. No other feature. This is only a large point cloud displayer so not intended as a replacement for rgl

Installation

PointCloudViewer is based on OpenGL and the SDL. You must install both first.

GNU/Linux

sudo apt-get install libsdl-dev freeglut3-dev

devtools::install_github("Jean-Romain/PointCloudViewer")

Windows

I successfully installed the package on a Windows machine once. It is a litte bit painful but not as much as your everyday workflow 😉. The following is a little bit dirty but it works (btw if it exists a way to make that in tidy manner on Windows please tell me).

1. Install a compiler and R developement tools with Rtools.exe
2. Download the SDL 1.2 developpment librairies files for Mingw here
   • Extract this archive
   • Copy the folder SDL that belong into the folder include to C:\RBuildTools\3.4\mingw_64\include\ or any other place like that depending on your computer and your R version.
3. Download the SDL 1.2 runtime librairies files for 64-bit windows here
   • Extract the archive
   • Copy the file SDL.dll into C:\RBuildTools\3.4\bin or any other place like that depending on your computer and your R version
4. Clone the repo, check the file makevar.win and update the path if requiered.
5. Compile the package

How it works

Displaying huge point clouds in real time is a complex task. Advanced techniques often rely on Octrees to selectively display points within the camera field of view. These techniques are smart but beyond my knowledge and not really appropriate for my low memory usage requirements. Considering how R stores data, constructing an Octree would require a full copy of the point cloud. This package uses some very naive optimization to render large point clouds in pseudo-real time:

• It relies on modern OpenGL, which by default is able to handle many points.
• When users rotate/pan/zoom it only displays 1 million points, which allows for smooth, fluid movement of the display.
• When the program finds a few milliseconds of free time between two events it progressively densifies the point cloud until the entire point cloud is displayed. This allows the user to rotate/pan/zoom again before the end of the rendering.
• It uses a pointer to the R memory and does not create any copy. The memory allocated for the rendering is therefore reduced to a few megabytes independently of the point cloud size.

So far it works well on my tests and the package can display as many points as the user wants (I stopped my tests after 35 million points [~1GB]).

Benchmark

On a core i7 with 11 million points.

Package	Time (s)	Alloc mem	Fluid
rgl	15-20	1.2 GB	no
PointCloudViewer	< 1	1.0 MB	yes

'Time' is the time taken to open the Windows. 'Alloc mem' is the extra memory allocated by the call. 'Fluid' means you can rotate and zoom freely.