Retrofit Reimagined - UAV Workshop with Paul MacMahon
NDSA Branch Secretary Paul delivered a workshop on UAV applications in Architecture
The workshop explained typical pre-launch procedures, safety methods and general functionality of drones for applications in architecture.
The group were told about the various aspects of pre site planning required for a successfully complete a survey.
Photo by Angela Grabowska (AG)
A selection of images were taken of the group from across the reservoir
(Photo: AG)
Each survey is uniquely tailored to achieving the aims of the survey. Output requirements, such as point cloud, will determine variables such as manual versus autonomous flying, flight frequency and duration, and speed of the device and camera orientation.
Further variables from the specifics of the site also come into influencing the planning of the survey flight.
Outputs achievable from UAV survey as such this can include:
Photo survey
Orthophoto
DEM
Dense Point Cloud
Point Cloud Classification
Cross Sections
Contours
2D CAD plans of buildings and site
2D CAD Sections
Dimension extractions from Point Cloud
Example of some of those outputs, or deliverables, can be seen below.
The workshop participants were able to observe the drone in operation from a safe distance.
(Photo: AG)
A shot from the drone looking back at the group from over the reservoir.
Some overhead stills were to be caopured.
A shot of the reservoir at the Centre for Alternative Technology. The camera was positioned at 90degrees to the ground plane.
The workshop participants were shown some of the real time flight data via the handheld controller display unit.
After steadily lowering the drone’s altitude a final shot of the group was captured before moving on.
The group moved onto another location, this time overlooking the main central area of the site. This demonstration included a photogrammetry mapping sequence for the purposes of producing a PointCloud and other associated outputs.
The Wise Building and immediate context at the Centre for Alternative Technology
The composite image below, and the Digital Elevation Model (DEM) beneath, was built with a sample of 50 high-resolution geo-referenced photographs and processed using photogrammetry software
An orthomosaic of the Centre for Alternative Technology derived from a Point Cloud model.
This flattened 2D image gives true orthographic projection with angle distortion eliminated.
The image is to scale and provides as measurable dataset with potentially high degree of reliability.
Colourised DEM of the Centre for Alternative Technology showing the respective heights of natural and human made structures above sea level.
Above: A Dense Point Cloud segment from the larger point cloud model of the site
Above: Dense Point Cloud Confidence mapping
Above: Solid Mesh generation
The models lack of definition is a consequence of the lack of rigour in capturing the images, where ordinarily for the purpose of generating any kind of photogrametry output a higher concentration of images is required.
Sufficient overlap and coverage of structures is necessary to get a more crips, clean and authentic representation of the structure.
Above: Solid mesh with RGB information from source photos projected onto model for photorealism.
This brief demonstration still permits a quick and easy result.
More complete results are possible with some further care in planning and completeness of assets captured during the operation.
Above: The camera are marked in black. They show the respective locations of the camera relative to one another.
Considerably higher overlap will be required for improved accuracies of the final models.
Above: The Wise building
Above: An overview shot from above the Wise Building.
To watch as the sun set behind the mountains while a carpet of fog crept in between the trees was a fine way to conclude Retrofit Reimagined at the Centre for Alternative Technology