msc poster: terrestrial laser scanning vs photogrammetry

TERRESTRIAL LASER SCANNING (TLS) The Dougalston Estate Doocot in Milngavie was laser scanned using a Leica ScanStation C10 Laser Scanner adopting the traverse method. The Doocot exterior (above) was scanned at a resolution of 10mm at 20m and the interior (above) was scanned at a resolution of 5mm at 10m. The exterior point cloud is composed of six scans and the interior was captured by a single scan. The TLS data was processed within Leica Cyclone 8.1 where the scans were registered using auto-constraints into a single coordinate system and cleaned using the Fence tool. A fly-through animation was created within Leica Cyclone. COMPARATIVE STUDY The purpose of the project was to compare TLS and Photogrammetry for Digital Building Conservation and offer recommendations. Comparison criteria included the point cloud accuracy, equipment, hardware and software requirements of each methodology. Steel tape measurements were compared to equivalent measurements on the TLS and Photogrammetric point clouds in order to assess accuracy. TLS point cloud accurate to 4mm SfM point cloud accurate to 16mm Cloud Compare deviation analysis computed positive (red) and negative (blue) distances between the point clouds, highlighting areas of variance (below). TLS produced a more accurate point cloud than Photogrammetry. However, SfM proved to be cheaper and the SfM 3D Model represented the real-world appearance of the structure better than the TLS. The comparative study concluded that neither method is superior to the other. Ultimately, the project survey requirements will dictate the selection of either methodology for Digital Building Conservation. PHOTOGRAMMETRY The Structure-from-Motion (SfM) Photogrammetry technique was used to create a 3D model of the Doocot (above). Imagery with suggested overlap of 60-80% (Stal et al., 2012) was acquired using a Nikon D3X 24.50 Megapixel DSLR camera and Agisoft PhotoScan Professional software was used to create the final 3D model. The image-set was refined and run through the workflow within Agisoft PhotoScan Professional software (right) to create the final 3D model. A fly-through animation was created in Blender that encircled the 3D model to display the quality of the SfM output. Geospatial & Mapping Sciences MSc Project By Peter McCready For Further Information Contact: [email protected] TLS SfM DIGITAL BUILDING CONSERVATION A comparative study between Terrestrial Laser Scanning and Photogrammetry. A case Study of the Dougalston Estate Doocot in Milngavie. VS Project Supervisor: Professor Paul Bishop (School of Geographical and Earth Sciences) Sparse Cloud and Camera Positions Dense Cloud Mesh Textured Mesh PhotoScan Workflow Entrance View Back View 1 2 3

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Page 1: MSc Poster: Terrestrial Laser Scanning vs Photogrammetry

TERRESTRIAL LASER SCANNING (TLS) !The Dougalston Estate Doocot in Milngavie was laser scanned using a Leica ScanStation C10 Laser Scanner adopting the traverse method.!The Doocot exterior (above) was scanned at a resolution of 10mm at 20m and the interior (above) was scanned at a resolution of 5mm at 10m. The exterior point cloud is composed of six scans and the interior was captured by a single scan.!T h e T L S d a t a w a s processed within Leica Cyclone 8.1 where the scans were registered using auto-constraints into a single coordinate system and c leaned using the Fence tool.A fly-through animation was created within Leica Cyclone.

COMPARATIVE STUDY !The purpose of the project was to compare TLS and Photogrammetry for Digital Building Conservation and offer recommendations. !Comparison criteria included the point cloud accuracy, equipment, hardware and software requirements of each methodology. Steel tape measurements were compared to equivalent measurements on the TLS and Photogrammetric point clouds in order to assess accuracy.!

TLS point cloud accurate to 4mm SfM point cloud accurate to 16mm

!Cloud Compare deviation analysis computed positive (red) and negative (blue) distances between the point clouds, highlighting areas of variance (below).!!!!!!!!!!!!!TLS produced a more accurate point cloud than Photogrammetry. However, SfM proved to be cheaper and the SfM 3D Model represented the real-world appearance of the structure better than the TLS.!The comparative study concluded that neither method is superior to the other. Ultimately, the project survey requirements will dictate the selection of either methodology for Digital Building Conservation.

PHOTOGRAMMETRY !The Structure-from-Motion (SfM) Photogrammetry technique was used to create a 3D model of the Doocot (above).!Imagery with suggested overlap of 60-80% (Stal et al., 2012) was acquired using a Nikon D3X 24.50 Megapixel DSLR camera and Agisoft PhotoScan Professional software was used to create the final 3D model.!The image-set was refined a n d r u n t h r o u g h t h e workflow within Agisoft PhotoScan Professional software (right) to create the final 3D model.!!!A fly-through animation was created in Blender that encircled the 3D model to display the quality of the SfM output.

Geospatial & Mapping Sciences MSc Project By Peter McCready For Further Information Contact: [email protected]

TLS SfMDIGITAL BUILDING CONSERVATION!

A comparative study between Terrestrial Laser Scanning and Photogrammetry. A case Study of the Dougalston Estate Doocot in Milngavie.

Project Supervisor: Professor Paul Bishop (School of Geographical and Earth Sciences)

Sparse Cloud and!Camera Positions

Dense Cloud

Mesh

Textured Mesh

PhotoScan Workflow

Entrance View Back View

1 2

mailto:[email protected]