Efficient way(s) to render point clouds of 3D scan datas in cycles Problem: I would like to render a 3D scan data (so no volume) containing only vertices (no faces or edges) with colour informations in cycles.

Tried so far: I tried particles (spawning spheres on each vertices) but I couldn't get the sphere to have the colour of the vertex it spawned from and with lots of points it's takes a lot of memory.
I tried hairs, but it looks like they only get the right colour when there are faces, they stay black if the mesh only has sparse points (bug ?)

Answers:
I'm opened to all suggestions. Exact looking techniques are better, but if there are some holes in the rendering it's ok. So using the above-mentioned techniques if you know the right parameters to save memory and have colour information is ok.
It can be a version of that solution : http://www.blensor.org/node/27 working in cycles.
Answers with GSoC Projects versions are ok (the OpenVDB or DingTo ones for example ?)

To be met:
I use a 20 000 000 point cloud data and I only have 8G memory, the solution must be memory-efficient. To give an Idea of how much can be used for so many points : the 3D scan program it comes from renders it using only 400M Memory.
May be you want to check out this link to render a colored point cloud in Blender-

https://visheshvision.wordpress.com/2014/04/28/rendering-a-colored-point-cloud-in-blender/