Photogrammetry is very much a practical skill and craft. Both José and Simon spend time testing and proving new techniques and keeping the skills sharp.
Having a small subject that remains fairly static is the perfect object to test new ideas, methods and means. Small enough to not occupy hours of shooting and processing time but large enough to present enough of a challenge. The subject should be relevant too.
Whatever the subject the learning process sharpens skills and lessons we learned are fed back into commercial work and have been baked into and shared in the Accupixel Metashape Standard training course.
Land Based Testing
These small brick and concrete bunkers can be found throughout the UK. Constructed in 1940 they were designed as defensive structures but (thankfully) they were never put to use. Today most of them remain open, accessible and unused. A few in private hands are used as man caves or apple stores and one now serves as a base for a mobile phone mast.
All of them make excellent subjects for testing and those with accessible interiors push the skills if the complete structure – internal and external – is needed. The added value of scale and GPS referencing can be applied and verified with simple real world measurements.
The preservation of cultural heritage is an added bonus and having a digital copy will never replace the original and very few are protected. If the bunker is lost the digital version can inform future generations what has been lost.
Simon really enjoys the challenge of underwater photogrammetry and it will come as no surprise there are a few test sites commonly used and Vobster Quay Inland Diving is home to two of them.
The armoured personnel carrier has been used to test and verify UWIS navigation and position recording for 3D reconstruction but the most popular test site is the Ford Escort that was dumped into the quarry before it opened for divers.
Being thin walled the car body is always a challenge to scan but its the go-to target to test lighting and shooting techniques. Since 2018 changes have been recorded with the position of the bonnet changing over the years as visiting divers add their own mark and rearrange the site.
Analysing the Rust
Ortho photo tools in Metashape Professional allow us to measure directly the area of rust. By drawing a polygon around the area we can then report the perimeter and volume of the area of interest:
The 2018 version of the car has less deterioration and rust presentThe ortho photo – as hosted by drone labs – can be viewed here:
Train and Practice
Training really is the start of a journey. Education provides a foundation from which follows repeatable and consistent results. The Accupixel Metashape Standard course – as endorsed by Agisoft – equips the student with a set of skills and knowledge that can be applied to any 3D reconstruction scenario. Being underwater presents its own challenges yet the forensic techniques taught are valid and the course is build on the years of experience accumulated by José and Simon: