This post is about one particular use of laser scanner point clouds collected in the field. After several scans are acquired and are correctly georeferenced, using a total station, GPS or other systems, plan and elevation drawings of the scanned features can be drawn in CAD. Using the Bentley Pointools plugin for AutoCAD 3D, it is possible to display sections through the scan data in the vertical or horizonal plane (x and y axes). This appears onscreen as a thin line of the point cloud, which can be traced as polylines to generate CAD drawings of building plans and elevations, with details of faces and sections where necessary.
The great advantage of using this techique is that the onsite data acquisition is far faster than taking measurements by hand, and the data can be later exported back in the office. So it was that I worked with laser scan point clouds (scanned using the Faro Focus 3D) and a photogrammetric 3D model (processed in Photoscan) of the Monk’s Oven and Pump House at Calder Abbey , a site I have never visited, in order to produce elevation and plan drawings using CAD. Special thanks to David Andrews for his patient tuition in this!
These are the plans and elevations of the Pump House that I drew, with additional corrections and editing by David. (All images and drawings: copyright Historic England).