Tuesday, December 3, 2013

SCRUG 11/2013

SCRUG 11/21/13 Was all about tools for scanning existing buildings.
The presenters were:
John Russo, President / CEO at Architectural Resource Consultants
Nicholas Kramer, Director of Technology at Perkowitz+Ruth Architects
Edward Tallmadge, Strategic Account Manager at U.S. CAD
The history:
• Tape measures, photographs, record drawings, hand held laser
• Static laser, on a tripod, scan, move, repeat
o Each scan takes 5-10 minutes
o Line of sight based
o High level of accuracy
o Reflective and black surfaces are challenges
o In one day a crew of two can make 50-70 scans
• Mobile scanner, auto mounted, uses GPS
o Less accurate than static
o Used for transportation projects
• Mobile interior, +/- 4” accuracy, very fast
• Air born LiDar, less accurate than other methods
Registration – a series of scans must be knit together, match corners that appear in adjacent scans, common physical targets
• Minimum: three common points
• Registration is bringing scans into alignment, a small drift or rotation between scans can compromise the accuracy
Survey control: “total station laser” – use a identification point with a high degree of accuracy, adds cost
Registered scan data is very accurate – can use for walk throughs or fly bys
Processing the data: point clouds can be in the 2-3 gigabyte file sizes, but once created the data may be used for 2D or 3D modeling
Beverly Hills HS: 2D fa├žade study, good accuracy, captured all the detail that would have been dangerous to measure in the field
The Embarcadero: No record drawings available, wanted to create a view & shadow study for city approvals without alerting neighbors, 2-1/2 days for a massing model, $8,000 in 8 days
Beverly Hills Hotel: captures interior detail with a high level of accuracy, custom moldings
OC Performing Arts: point cloud animation, 2 hours to capture data, no targets, 4 hours to register data, ~$3,000 for a quick visualization
Engineering: capture structure, piping, HVAC, accurate to rivets
Contractors: scan before construction, scan during construction, verify plumb, verify flatness, scan a boulder to determine volume
The biggest cost is the modeling of the scans

As part of the laser scanning some models offer cameras and take photos with a second pass. Photos are knit together and then become measurable panoramic 360 degree photos. Manufacturers: Leica & Faro

Light requirements: laser is its own light source, for the digital photos, you need a light source

Short range scanners have a 100 meter range.
Long range scanners have a 300 meter range.

There is a Revit add-on that will place walls and other components when you click on a point cloud.

Photogrammetry – Autodesk Recap 360 : makes point clouds from a series of photos. Upload your photos and their servers will try to knit them together. Free for now. Use a 12 megapixel camera or higher res. You can adjust the registration with the “Pro” version . 2-3” accuracy is possible. Photos may be taken from any digital camera. Overlap images 50-70% for best results. If you want to use a quadcopter w/ GoPro camera, get FAA license & insurance. Entry cost for the quadcopter setup is ~$6,000. Recap does not know what scale things are. You will have to have at least one real world measurement to set the model to the correct scale. Trees & plants don’t capture well.
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