Product Profile: Panoramo SI 360 Manhole Scanner
January 1, 2011
Why Inspect Manholes?
A manhole is essentially a vertical pipe that provides accesses to the horizontal pipes that form a collection system. An 8-ft deep manhole of typical design has about the same surface area as a 50-ft segment of 8-in. pipe. When thought of in terms of surface area, manholes are major sources of structural defects in the collection system. Manholes ought to be a major priority for inspection and rehabilitation when the general age and condition is considered. In the United States, there are at least 20 million manholes in the ground, with about 50 percent of them installed prior to 1960. Typically, a manhole will last 50 years before it requires serious maintenance and rehabilitation, and as of now, it’s estimated that 18 percent are experiencing serious structural flaws. Because of this, manhole inspection is becoming more and more important to the goals of collection system maintenance.
In 2003, inspection camera manufacturer IBAK introduced a new pipe inspection method merging innovations in computer processing with digital camera technology and advanced robotics: Panoramo 360° Optical Scanning.
Panoramo scanning technology uses two high-resolution “fish-eye” cameras, each with a 185-degree field of view and facing opposite directions. As the cameras move, either through a pipe or a manhole, digital snap-shots are taken from each camera at 2-in. increments in the pipe. Images are transmitted to the inspection vehicle instantly via a fiber-optic cable in binary code.
The digital Panoramo cameras use flash illumination through triggered strobe lights with an exposure time of 0.0005 seconds per picture, compared to analog CCTV, which uses continuous illumination and a much slower exposure time of 0.04 seconds per picture. This difference in camera technology enables continuous travel at the relatively high rate of speed of 70 ft/min (14 in/sec), almost 10 times faster than the average CCTV speed of 7.38 ft/min (1.48 in/sec).
IBAK’s software combines the images, lining up each forward and reverse picture from corresponding distances to create the 360-degree field of view for an interactive file with “virtual pan and tilt” to see any object in the pipe from multiple angles. An unfolded image of the pipe is acquired by connecting high-resolution segments taken from approximately an 85-degree field of view with the front camera. Data is displayed in an IBAK Panoramo File (IPF). For viewing on a separate computer installation, a 12-MB, Window’s-based PanoViewer.exe free-ware program is required.
The Panoramo SI unit is mounted onto a pendant (10-in. diameter) with an integrated gyroscope and is suspended from the end of a cable. The process to inspect a manhole involves the operator remotely lowering the device to the invert and then retracting the cable. Because of the complete visual scan generated, human error on the part of the field operator can be eliminated to a far greater degree than any other method available. Also, the unfolded view allows for a significantly greater amount of detail at 3,000 horizontal lines of resolution, compared to approximately 470 lines for most CCTV cameras.
Perhaps the most valuable feature related to Panoramo SI, however, is its ability to produce geometric data on the manhole in the form of a 3D “point cloud” profile. The down-hole facing camera, as it takes pictures every 2 in., photographs stationary objects from multiple points. The Panoramo software accounts for contrast variance in the pixels representing these objects from multiple points. By comparing the change in contrast to the position of the camera, the object’s position can be triangulated and represented as a dot in a 3D space. The “point cloud” consists of thousands of dots. 3D measurement is possible in the profile and measurements in the 360 perspective view can be applied to the profile with the use of PipeLogix software, enabling quick and accurate identification of pipe diameters, analysis of manhole barrel/chimney ovality and rim to invert measurement.
Benefits to this level of analysis are numerous, such as new construction inspection, determining hydraulics and flow capacity of a collection system, identifying structural defects in older manholes, as well as for implementing rehabilitation products. The 3D profile can be saved in DXF format and exported to AutoCAD, making possible wireframe meshing and measurement of surface area, angles, perimeters and volume. Rehabilitation projects can now be tailored to specific conditions for the most cost effective repair method, enabling materials to be prefabricated, saving time and money.
Case Study for City of Portland, Ore.
Organization: Portland Bureau of Environmental Services (BES)
Background: Service Population: 614,000. Approximate number of BES manholes: more than 30,000
Collection System Type: some Combined Sewer, mostly separate Sanitary and Storm Sewers. Date of field test: 1/7/10
Applications:
- Inspection of brick manholes in residential neighborhood
- Determine level of production relative to time onsite
- Total time in the field: 5 hrs, 20 min
- Number of manholes inspected: 36
- Average Number of manholes inspected/hr: 6.8
- Notable findings: The majority of brick manholes inspected (most more than 100 years old) were in satisfactory condition. In one manhole, a vertical fracture on the base near the bench was discovered with damage to bricks and mortar with possible structural damage. The unfolded view proved useful in identifying this defect as it enabled viewing the entire surface of the sidewall to zoom in and measure the width and length of the fracture.
Conclusions
Evaluation of the Panoramo SI system can be summarized in three categories: field production results, deliverables and analysis of data and data integration into a database.
Field Production
Case study findings verified the increased efficiency and productivity over traditional methods of data collection. Depending on field conditions such as traffic flow, ease of manhole identification and vehicle access, the Panoramo SI system enabled inspection of, on average, between 6.5 to 9.46 manholes per hour in the field.
Deliverables
Panoramo SI’s deliverables include a complete 360-degree interactive field of view, an unfolded view of the entire manhole surface, a “scan overview” with a thumbnail sized unfolded view, and a geometric point-cloud profile. These four analysis tools can each be manipulated independently of each other, and, importantly, at any time or place after the inspection has been completed in the field. This type of interactive deliverable, which separates data analysis from real-time field inspection, offers a unique benefit no other inspection method can match.
Integration of Data
In the field, data is acquired and rendered using IBAK’s Panoramo Scanner software. Optionally, data can also be captured within PipeLogix’s 360 module, an inspection reporting program developed by a third-party software company of the same name. In PipeLogix 360, the operator enters pertinent data of manhole location and identification number prior to conducting a scan. PipeLogix 360 then initiates the IBAK Panoramo Scanner software for the inspection and the scan data is taken and stored in both PipeLogix and also in the software provided by IBAK.
Depending on the file size or quantity of data collected, files are downloaded or burned to CD-R data disc, USB thumb drive, or external hard drives for viewing on other PCs. Additionally, IPF files are stored and viewed within PipeLogix 360. Use of PipeLogix has several advantages, namely, large numbers of manhole surveys can be easily archived, searched, and imported into a GIS database, just as traditional CCTV surveys are handled. PipeLogix also enables standardized coding and reporting of observations. A technician certified by NASSCO has the ability, using the Manhole Assessment and Certification Program (MACP), to use PipeLogix’s reporting interface to produce a fully coded MACP-compliant report for consistent structural, construction and operation and maintenance condition ratings.
Eric Sullivan is business development manager for Atlas Inspection Technologies.