|A large ornithopod footprint in the back garden of a collector on the Isle of Wight.|
Not so easy to share with your colleagues across the world? You can with photogrammetry!
Photogrammetry is one of these techniques. Most palaeontologists and amateurs will already have the tools to practice photogrammetry in their field kit: a camera and a laptop. In fact, your mobile phone and an internet connection will enable you to produce reasonable quality 3D data very little time using free software, downloadable right now.
So what is photogrammetry? It's the technique of generating a 3D point cloud from a series of overlapping photographs and at it's most basic a mesh can be generated from a stereo pair, but in most cases more images are better. It is capable of sub-millimetre accuracy and can capture virtually any subject, including outcrops and objects in the round. Photogrammetry has several advantages over traditional techniques. As mentioned earlier most of us having the equipment needed as part of our regular field kit and vitally photogrammetry is totally non-destructive and this is important when recording delicate fossils as well as tracks and traces as often a traditional technique (for example creating a mould) will cause some damage to the fossil as part of the process. The software used to generate the 3D data is free, multi-platform, open-source or relatively cheap and capable of excellent results.
|Chirotherium footprint, textured 3D mesh.|
One example of a photogrammetry workflow is as follows:
- Take overlapping photographs.
- Load into photogrammetry application.
- Generate a point cloud (the software looks for points on the various photos and these are assigned a point in 3D virtual space).
- Generate mesh and texture (if required).
- Output, analyse and share.
The 3D data has one huge advantage over traditional data: it's very easy to share. You could record a specimen in the field, generate a point cloud and the a mesh, save it into any one of a variety of formats read by a variety of apps. This data could then be emailed, uploaded and shared with colleagues across the world, all from your position in the field (provided you have internet access).
|Another Isle of Wight footprint, this time a theropod track which some gooner has|
tried to remove with a rocksaw. I recorded it using photogrammetry and did no damage at all.
An untextured 3D mesh.
This data has a wide variety of uses. The point cloud and mesh generated from it can be used for morphological analysis, measurements, false colour and contour analysis and light sources etc can be manipulated to aid interpretation. The meshes can also be 3D printed to bring the specimen back into the physical realm; want to have a scaled 3D version of that Allosaurus skull you excavated last field season on your desk? Use your photogrammetry data!
PG data also has potential as uses when publishing research, as stills in a paper and animations and meshes supplied as part of the supplementary data of papers. 3D works particularly well for outreach too, with animations and 3D video particularly useful for encouraging engagement.
So how to start in photogrammetry? Watch this space!
*You might notice this post is ichnology-centric. For that, I make no apology at all.