Structure from Motion Photogrammetry (SfM photogrammetry) is the creation of scaled, measurable 3D digital models of objects or terrain from multiple overlapping images.
Advanced processing software and hardware are used to correlate specific points found in photographs taken at different angles, generating a point cloud which may then be interpolated into a mesh structure.
All of our models are ortho-rectified and scaled to permit accurate measurements to be taken from them.
The models produce permanent records that can be measured in three-dimensions to much higher levels of accuracy than are possible using traditional methods. The models can be examined for a variety of physical characteristics and successive surveys can be used to quantify change over time.
Our delivery can be generated using still or videographic imagery obtained through multiple capture techniques including diver, ROV or aerial drone.
We can now combine underwater models generated by diving or ROV, with above water ones constructed from aerial drone images to deliver models of complete coastal structures.
We started using this technique underwater in 2013 under the auspices of the National Facility for Scientific Diving. Over the years we have greatly enhanced our delivery of underwater models through the employment of dedicated operators and the development of a networked cluster for photogrammetry processing. The photogrammetry cluster uses several dozen computing cores distributed across four workstation-class nodes to form a parallel processing supercomputer. This network architecture allows simultaneous or sequential alignment of tens of thousands of images and the creation of terabyte-scale projects.
Services offered using photogrammetry
Monitoring surveys of at-risk structures
Repetitive surveys to monitor degradation or corrosion; identification of areas where preventative maintenance could be applied.
Ex-situ identification of damage; complete survey coverage in low-visibility environments.
Biofouling volume and mass calculations; holistic structural survey.
High resolution seabed coverage for aquaculture or invasive species; impact assessment using change-over-time studies.
Habitat and niche availability for benthic-associated species; environmental complexity using a range of metrics such as 3D rugosity, fractal dimension and kurtosis.
Benefits of photogrammetry over traditional survey methods
Scaled, measurable digital models
Models are accurate to sub-cm scales
Permanent, 3D digital records created
Successive models can be compared to quantify change, e.g. corrosion/erosion
Non-invasive and rapid data collection
No measurement tool need be applied directly to the object’s surface. Important for fragile structures or delicate ecological features
Measurements or analyses can be performed remotely by engineers or scientists
Repeat measurements can be performed on legacy data as new questions arise
Models may be subjected to further intensive study using machine learning algorithms to detect key features