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2001
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Pipeline R-O-W management at light speed
A typical sensor suite for these applications will involve a terrain scanning LIDAR, digital imagers
and DGPS/IRU. The scanning laser, firing through a scanning mirror that paints a swath up to 60° in
width, returning the ‘hits’ from everything underneath. It ‘builds’ a three dimensional numerical
model of the area, completely and precisely georeferenced (Figure 5). The digital imagers, video and
frame are simultaneously imaging the terrain in the visible and I/R spectrums, providing the ability to
"armchair quarterback" the assets from the desktop without resorting to expensive and timeconsuming
field surveys. The same planimetric mapping and elevation data previously employed can
be provided faster and less expensively. What’s more, they can be integrated with true visuals of the
corridor, provided through the ortho-rectification of digital camera data, much the same as the
outputs from the photogrammetry process.
The differences with this new mapping technology are striking. First, processing can begin
immediately, often before the data acquisition project is complete. Digital data sets can be
transmitted over the internet effectively or burned to CD-ROMs and expressed back to a processing
base (the client receives an immense advantage here over traditional methods, with data acquisition
and processing times often many times less than conventional aerial photography/photogrammetry).
Second, the specific helicopter platform can vary its speed to provide a denser data set along the
corridor, as per client specifications. For example, if stream crossings are a particular sensitivity, or if
compressor stations are most critical for engineering or maintenance needs, the platform can hover or
move slowly to pick up the density needed. Finally, the outputs of the process are readily sleevable
into any off-the-shelf or custom GIS. Imagery can be provided in tiff, jpeg, dwg (AutoCad) or any
other format, and the data sets themselves are transferable to any system. Most firms, including
Terra, use a combination of proprietary software algorithms and commercial image processing
software to turn the data into imagery suitable for either the end users, or mapping outputs suitable
for immediate integration into a GIS.
Case Study: Williams Gas Pipelines
Williams Gas Pipelines delivers over 16 % of the natural gas in the United States of America through
its 27,000 mile (and growing!) gas transmission system. As the power crisis in the west heated up,
literally, it investigated alternative technologies to deliver its mapping needs for FERC, state and
county regulatory purposes. As regulatory agencies shed their traditional “hurdle” image and began
actively encouraging new capacity, Williams needed to ensure that time bottlenecks didn’t surface in
its own ability to conform, design, build and operate.
Key issues for the company were corridor mapping accuracy, precise elevation data, and “speed to
build”. It also needed a better handle on its own right-of-way from the standpoints of encroachment,
liability and ongoing regulatory compliance. Design and upgrading issues were becoming
increasingly important, as existing rights-of-way also often offer the best opportunities for increased
capacity.
A proposed gas transmission pipeline along an existing 60 mile long corridor needed to be mapped
and submitted to regulatory authorities within weeks. Included was an alternate 8 mile routing for the
new line. Legacy mapping was not up to par, and both ground and traditional aerial survey
methodologies could not come close to meeting critical path deadlines for design and construction.
Terra assessed the needs with Williams and configured a sensor package that could resolve all of the
issues. The terrain scanning laser (LIDAR) produced the bare earth ground DEM (Figure 6) and
vegetation profiles for corridor management. High resolution digital imagery provided precise
capture of the entire right-of-way, and a half-mile buffer zone for alternate routings (Figure 7).
TRSI’s CAD group also produced planimetry options for maintenance purposes – actual georeferenced
imagery overlaid on existing legacy data (Figure 8).
TRSI’s system was mobilized and flew the entire corridor in a 2 day period. Processing began
immediately on return and the full digital elevation model (to 6 inch vertical accuracy) along with
seamless ortho-mosaic imagery of the entire 68 miles was delivered to the client within four weeks
of mobilization.
Summary
LIDAR systems are a fast, precise and cost-effective means to acquire, process and deliver critical
geospatial data for energy supply. Their flexibility and data output format provide the additional
advantage of being able to easily populate the enterprise GIS database for further manipulation by, or
for, the end user.
Geographical Information Systems are no longer simply useful corporate appendages for geospatial
data sets. They are becoming a core focus within large corporations for long term strategic thinking.
Senior management can, and should use the available information to realize substantial cost savings
for the management of significant assets.
Figure Legend
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Figure 1: LIDAR Bathymetry Basics
The underlying principles of operation for LIDAR bathymetry are to measure depth by measuring
the time/distance between the laser pulse reflected from the surface of the water and that of the
bottom
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Figure 2: VideoMap and Laser Bathymetry Integration
Geo-referenced imagery and airborne bathymetry are integrated to provide clients with easy
visual references of features and depths
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Figure 3: VideoMap Image
A typical oblique geo-referenced VideoMap view
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Figure 4: Sensor Rack
Terra’s sensor rack mounted in a Bell 206B JetRanger helicopter
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Figure 5: Laser Data Set
Color-coded bald earth and vegetation model of a typical gas transmission corridor
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Figure 6: Vegetation Point Cloud
A point cloud of vegetation and other encroachments overlaid on the bare earth corridor
Figure 7: Ortho Products
Seamless ortho-rectified mosaic of the proposed pipeline corridor
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Figure 7: Orthos on Legacy Data
Seamless ortho-rectified mosaic overlaid on existing legacy data
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