I need some advice on photogrammetry. Is there anyone here that has used these methods and would be willing to provide some pointers?
Specifically, I am aiming to create a 3D model of a bat cave (50 m deep, 10-20 m wide). Any guidance appreciated, on standard methods, equipment, and software.
Many thanks
Ollie
20 January 2017 11:24am
Hey Ollie!
This strikes me as something quite similar to what some of the folks in the drones world are trying to do with mapping forests, except basically inverted. @Tomswinfield shared an overview of what he's been working on in this case study: 'Can UAVs be Used to Measure Forest Quality', which may be a place to start to see if there are any similarities in what you're thinking. @Tomswinfield , @Felipe-Spina and I had a fascinating discussion this very morning about this approach, so perhaps one of you could offer Ollie some pointers?
Cheers,
Steph
20 January 2017 11:29am
Hi Ollie,
I've only used UAVs to map forest canopies but the principal is the same:
- Multirotor UAV with a camera pointed towards the surface to be mapped (aim to keep the angle relatively constant)
- Create a flight map that enables you to collect equally space images with >60% overlap with adjacent images (in all directions); this can be achieved easily with Mission Planner, particularly if you have a constant flight speed and the camera is triggered by an intervalometer. You could alternatively set images to be taken at particular way points.
- Use Structure From Motion software (e.g. Pix4D / Photoscan) to build your 3D model as a point cloud or render to a mesh.
- Job done.
Any more questions, just ask.
Tom
20 January 2017 12:26pm
Thanks for that Tom!
As a broadly knowledgeable beginner, reading your instructions makes me wonder if it might not be valuable to have a step by step guide that is a little more detailed than that on getting started (and I'm by no means suggesting you need to write it!). @ollie.wearn , as someone just getting started, and @Felipe-Spina , as someone a little bit futher along but still experimenting and learning, what do you think? Would a simple 'how to get started using your drone to map in 3D' (with a hopefully snappier name) sort of guide be a useful thing to develop for others coming after you? Or does this sort of resource already exist?
I should say - anyone else with thoughts or suggestions on Ollie's original question or my follow up here, please do chime in as well!
20 January 2017 12:45pm
I'm definitely up for that!
Stephanie O'Donnell