Creating Point Clouds From Photogrammetry
Laser scanning is the current big technology, with large projects demanding tighter schedules and more varied deliverables that only scanning can provide. Scanning, however, isn’t the focus but rather the point clouds that the technology produces. Scanning is embattled with the much older photo profession in its search for cloud creation dominance, and for one good reason: the setup for ground-based photogrammetry work costs 10 times less than the cheapest scanner and still ultimately produces a point cloud. What scanners provide is a consistent product in one step. Doing it through photos adds complication to the process but is substantially cheaper.
Professional work requires professional tools. All professional systems cost something, so trying to learn how to use point clouds in the first place can be a bit intimidating. To ease the stress, try using a smartphone camera and Photosynth to create a photo-based dataset. To get the data out, use the program SynthExport and upload the dataset into a cloud-capable system. Any CAD program with a license after 2008 should have a point cloud plugin; most after 2010 have an integrated tool. Meshlab is probably a better bet for first-timers since it includes an importer that uses Photosynth directly. Meshlab can also process point clouds and is a common tool even in large companies. There are plenty of great videos on how use the software.
Once you’ve figured out how to create point clouds with photos, you can begin experimenting with other tools that can produce point clouds on par with scanners if done correctly. One of the most interesting systems is PhotoModeler Scanner, which has been used on dig sites, shoe-print reconstruction, and DTM creations. The PhotoModeler website also hosts many videos and tutorials on how to create point clouds and is another great learning resource.
Being successful in creating ground-based point clouds will eventually require a scanner, if just for the simplicity. However, learning about photogrammetry can still pay off by allowing you to take advantage of the coming drone systems. Scanners will likely be too heavy to mount to a lightweight drone, but camera systems are perfectly situated to take advantage of the autonomous platforms. (For example, consider what might be accomplished with a Parrot Drone 2 and a trial of Photomodeler Scanner.)
For those who know about scanning but don’t think they can get into the workflow, photogrammetry-based point clouds provide an inexpensive way to get started. Share your thoughts and experiences below.
Image: PhotoModeler Scanner