I think the stonehenge / durrington walls LIDAR video is excellent but perhaps for ignoramus's such as me you could put a short technical explanation on the same page, e.g. what does the acroynm LIDAR stand for and what causes the spikes that appear in various places.

The Durrington Walls ring really shows up well. It is not at all apparent when passing the spot through at ground level unless of course you are an expert.
Thanks
Nigel

LIDAR stands for LIght Detection And Ranging. There's a good explanation on Wikipedia, which isn't far off the mark: en.wikipedia.org/wiki/LIDAR

The spikes often indicate the presence of trees or tall vegetation. In this 'unfiltered' dataset, when the laser hits the canopy some readings are returned from the ground, some from branches and leaves. You end up with hundreds of millions of points in 3D space (known as a "point cloud").

When turned into a 'solid' computer model as you see here, areas where points in the air (the top of a tree) are very close to points on the ground (the laser scattering through branches and hitting the ground, for example) you get a zig-zag effect, causing the spikes.

I hope that explains at least some of your questions!

No offence Tom, but I'd like to say that sentence which appears in the video saying: "...visible in incredible detail..." sound for myself quite riddiculous. The Stonehenge is 'only' about 20-30 spikes which doesn't say much if you don't know what's that and do not recognise the shape. I work for LiDAR mapping company based in UK, and recently had a chance to deal with a 200kHz Airborne LiDAR data which has got about 3-10 cm elevation accuracy and 5cm plane, giving enormous point cloud of more than 200 points per sqm. That's brilliant, but the one in the video is just poor.
Apart from that, I'd like to say that your video impressed me a lot, with rendering of light and fly-through quality. If I could use the kind of software you did, I'd take you of your feet probably :)

Hi Karol,

I'm glad you liked the general production of the video - it was quite a challenge to do!

Since you work with LiDAR, you may know that much of it in the UK is collected by the Environment Agency, who kindly have us permission to use this dataset. Archaeologists have very little in the way of resources and money, so we have to make do with what we can get hold of. This data is several years old (2002, I believe), and in its time was utterly amazing for us as archaeologists. This video and dataset is still very useful to archaeologists to help us understand the lay of the land, and see some of the more eroded monuments more clearly. Compared to some of the information available to us, this *is* incredibly detailed.

As far as I'm aware, no other higher resolution dataset exists for this area (except around the River Avon). We are certainly aware that the LiDAR technologies are improving all the time, and much higher resolution data can now be collected. However, if any higher resolution data for the Stonehenge World Heritage Site exists, we currently don't have access to it.

As for the stones themselves, terrestrial 3D laser scanning is more appropriate to record the stones themselves, and close-range (sub-millimetre) triangulating scanners more appropriate for the recording of detailed features such as rock art on the stones themselves.

One day we'll be able to tie in all the data together, and that *will* be amazing!