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Based In the Great Pacific Northwest
Moitek Aerial Imaging is a member of AITSCAN which is considered THE BRAND
for high quality aerial infrared thermography in the United States.
Traditional ground based methods of pollution source detection have many limitations, and are time
consuming and labor intensive. Traditional methods do not provide effective coverage of large
surface waters where so many problems go undetected. Municipalities have become interested in
utilizing alternate, recognized, cost effective methods of source detection.
Image quality reduced for web display
Conduct qualitative aerial infrared thermographic surveys of sewage and storm water drainage systems to identify specific areas where
leaks are occurring so that action can be taken to abate the leaks.
Background
Polluted water contaminating the surface water and drinking water supply has been identified by the EPA as one of the most serious
environmental problems facing the United States. Leaking sewage collector lines, storm water drain discharges and illegal taps into
storm water drainage lines can often be identified by their thermal infrared signatures during certain times of the year. As these sources
of pollution leak, seep or empty in creeks, streams, rivers and lakes, their thermal signatures vary from their surroundings and they can
be pinpointed accurately from the air.
This flow of liquid typically appears warm as compared to the surface water in a creek, stream, river or lake - particularly during cooler
times of year, due to the relative warmth of the ground a short distance below the surface. Leaks from nearby lines often come to the
surface through lateral transfer to a creek, stream, river or lake bed, or to a slope leading down to the surface of the water. These leak
areas and the warm plume of liquid joining and flowing downstream with the body of water are visible in the thermal infrared spectrum
due to the difference in temperatures of the two liquids. Late fall, winter and early spring are well suited to this type of inspection because
of the different water temperatures (ground and surface waters) and because the interference to view by foliage is minimized. Ground
water seeps and outfalls of all types are also easily distinguishable for similar reasons.
Understanding Infrared Imagery
Infrared imagery is often a gray scale picture whose scales (or shades of gray) represent the differences in temperature and emissivity of
objects in the image. As a general rule, objects in the image that are lighter in color are warmer and darker objects are cooler. No object
in the images is detected via visible light wavelengths (400-700 nanometers) rather, only from infrared wavelengths in the 3000-5000
nanometers or in the 3-5 micrometers range. Lights and other relatively hot objects are very evident, but as a result of their heat - not light
emissions.
When an image is taken with infrared camera, it is often recorded on video tape and later converted to a digital image file with the help of a
computer. The image may then be modified in a number of ways to enhance its value to the end user. The highest resolution infrared
images are usually found on videotape, while the printed thermographs and map data may be used as a convenient reference when
accompanying a report.
Platform
A well-maintained, single-engine fixed-wing aircraft with STOL package, digital navigational systems and auto pilot is utilized.
Infrared Imager
Two types of high-resolution thermal imagers are acceptable to be used to obtain the imagery.
1) Specifications: A high resolution, gimbal mounted, large-format thermal imager (PtSi 512x512 monolithic focal plane array), 58% fill
factor, pixel size (H x V ) 26 x 20 microns, detectable wavelength band 1.2-5.9 microns, field time 1/60 second, with a sterling-cycle cooler
is oriented "looking" straight down through a camera hole in the belly of the airplane.
2) Specifications: A high resolution imager with an Indium Antimonide (InSb) detector with three field of view, mounted in a
remote-controlled articulating gimbal on the aircrafts wing.
VED (Video Encoder-Decoder):
The thermal imager video output is routed through a video encoder-decoder (VED) that labels the video with GPS information. A bar-code
of the same GPS information is recorded on the far left side of the imagery and may not be visible on a conventional TV screen. This
bar-coded information, displaying the date, time to millisecond, number a satellites acquired, altitude, latitude/longitude, speed over
ground and compass heading, is used by the VED during post-flight analysis.
Video Recorder:
The annotated video imagery is recorded with a digital video cassette recorder using mini-DV tape capable of storing 500 lines of video
information. A laptop computer with Delorme Map Expert mobile mapping software is used to map flight lines.
The aircraft is flown over and along the surface drainage system in a manner that allows the creek, stream, river or lake to be imaged
and recorded on digital video tape. In the cock pit, the moving map software with "bread crumb trail" feature, permits the crew to monitor
their flight path and location with respect to the drainage area highlighted and guide the pilot along flight lines to insure complete
coverage. The aircraft flies at an average altitude of 1,500 feet above ground level. The recording device is often paused during the turns
outside the study area so that extraneous imagery is omitted.
Analysis Methodology
After the flight, the imagery is analyzed by playing back the videotape using digital VCR, a high-resolution TV monitor and an integrated
computer system with video capture hardware and software. As the tape plays, The VED decodes the bar-coded GPS signal that was
received and recorded during the flight. The VED then recreates the original GPS signal and sends it to the computer so that the mobile
mapping software "thinks" it is receiving a live signal. The mapping software shows the moving position of the airplane superimposed
on a street map on the computer screen while the recorded infrared imagery of the area below the airplane is visible on the TV monitor.
GPS updates the airplane position once per second throughout the flight and at the same rate during the post-flight analysis.
To find outfalls, the tape is viewed in its entirety, paused, played backward and forward at regular speed and in slow motion, as
necessary. For each hour of tape, many hours of analysis are required to complete the report. When the entire tape has been reviewed
and all anomalies are found, they are marked on the map and infrared thermographs are digitally captured using specially designed
hardware and software. The captured image displays the annotation data as a strip at the bottom of the image. The map is marked
using this information and updated showing the exact location of each anomaly with a flag denoting the report anomaly number
designation. The maps and digital images are then brought into image processing software and adjusted for contrast, brightness, etc.,
before being scaled and placed in report software for final editing. The final report includes a CD-ROM containing all files for the project,
and a video tape of the flight. A written report noting flight conditions, scope of work, locations of the anomalies along with the printed
maps and high-resolution images are then printed on photo quality paper.
With all system anomalies marked on a map, the system operator can prioritize areas of
concern and concentrate efforts and scarce resources on those locations first.
The printed report and map data will allow the operator to easily locate and test suspect
areas.
High-resolution images that capture large areas at once. Plan view imaging result in a report
that is clear, concise and easy to understand.
High-angle, straight down infrared images for increased accuracy, or, very high thermal
sensitivity, gimbal mounted camera for ease of creek and shoreline tracking.
A more cost effective platform to obtain infrared imagery, than rotor-wing, while reducing
ferry times and vibrations.
Previously inaccessible or hard to reach areas of the system are monitored.
Instead of inefficiently using scarce resources to perform on-ground testing, resources can
be used to monitor problem areas only.
Cessna 170B. It's slow flight characteristics and smooth
running six cylinder engine (less vibration) make it an
excellent choice. It is also modified with two camera ports
in the bottom of the fuselage.
designed and built by Moitek.
Contact Us
Moitek Aerial Imaging
446 Moilanen Road
Longview, Washington 98632
360-430-0634 360-636-2974
WWW.moitek-infrared.com
Copyright 2004, All rights reserved
