3-D Terrestrial Laser Scanning

WSDOT Geographic Services uses 3-D Terrestrial Laser Scanning technology to produce very accurate, very dense 3-dimensional digital data sets (called "point clouds") used for CAD mapping. This technology is a fast, safe, and efficient way to model and measure many areas where it can provide advantages over traditional survey or photogrammetric methods. The WSDOT Geographic Services Photogrammetry & Remote Sensing Branch and Geodetic Survey Branch are highly skilled and experienced in this advanced technology. The Geodetic Survey crew scans the project while the Photogrammetry staff processes the data to the final 3D CAD deliverables.

 

 

 

 

 

 

 

The image below is a set of merged scans of the SR 167 and SR 18 Interchange.
The project will have close to a billion data points when finished.

• Greater safety for motorists and survey crews by working away from the traffic
• Decreased traffic disruption by collecting data from a safe distance
• Reduce the time collecting field data by 20-30% compared to conventional survey
• Reduce or eliminate return visits to the site
• Expand data collection to difficult areas such as slopes, tunnels, high buildings and structures.
• Enhance projects by combining photogrammetry CAD and Terrestrial Laser Scanning
• Georeference data (point clouds) using Global Position System (GPS)
• 3 dimensional virtual surveying
• Effective scanning range is 220 feet in all directions for roadway surfaces and greater for vertical distances.
• Integrated high-resolution digital camera provides coverage of scanned scenes.
• Point Clouds can be overlaid in the design file to facilitate interpretation
• Deliverable design file compatible with WSDOT design software and procedures.

Note: Terrestrial Laser Scanning is not a replacement for Survey and Photogrammetry. It is an additional tool to enhance the mapping process.

 

Data (Point Clouds) From The Terrestrial Laser Scanner Click images for larger view
Downtown Seattle	Seattle bridge over I-5 including express lane tunnel
3DTL Video 2min 11 sec	3DTL Bridge Overview Video
Convention Center Fence Bridge Point clouds illustrating As-Built  conditions accurately and in detail.	Bridge Cross Section216th Ave SW over I-5 north of Chehalis
Jersey Barrier 3DTL Video 45 sec	Bridge Cross Section 3DTL Video 48 sec
Map Products Created From Point Cloud Data
CAD Design File	Data Terrain Model
Contour File	Orthophoto With CAD design file overlay (the AWV tunnel mapping can be seen in this view)
Some of the Data Uses
Vital Roadway Measurements
I-405 Bridge Clearance Measurements	Measurements on a SR 167 Bridge
Measurement on SR 90 Latah Bridge	New way of mapping increases accuracy (Side View of Latah Bridge)
Structure Monitoring
Alaskan Way Viaduct, First Ave. Exit	Alaskan Way Viaduct South Bound
Bridge Survey
Substructure of lower deck on the Ship Canal Bridge Express Lane. Vibrations of traffic on upper deck disallowed conventional survey.	Individual scans represented by colors are part of the 3DTL technology that allow accurate data scans on moving objects.
Pavement Monitoring
BEFORE	AFTER
I-405 Road Surface with color scale. Green shows no settlement of the roadway while purple indicates pavement settlement from underground construction.
Snow Sheds	Nalley Valley As-Built
Archeological Sites Near Highways
Close up of a site	Overview of a site
Artifacts in the "dig" side view	Some Artifacts
Soil Erosion & PIT Site Volumetric Calculations
SR 12 Culvert Soil Errosion	2007 Pit D-245 Contours
US 2 Rock Slide Point Cloud (arrow indicates scanner)	SR View of the rock slide area.
Showing measurements that can be made even from very steep angles	SR View of US-2 slide area.
Utility Identification & Location
This image shows a utility box, traffic sign, guardrail and guide post.	SR 520 Overhead Sign Measurement
Data Handling
Scanned data sets can be enormous, reaching a billion points or more. WSDOT Photogrammetry uses enhanced computers and software systems to manage these massive data sets.  Photogrammetry produces standard WSDOT CAD files that can be used on regular computers used by project designers and planners.