Paper 2
Title: A Study of Human Target Tracking Using UV and IR Target
Features
By
Hemamalini Kannan
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Experiment:
A selection of UV and IR filters has been used for this study to explore target tracking
and / or target appearance using the UV and IR electromagnetic bands. Each filter is mounted
on a Sony Mini DV camcorder (Model Number: DCR-TRV17 NTSC)1. Targets are videotaped in various scenarios chosen to explore several cues like color and texture of clothing,
clustered environment etc. The images obtained in this study are actual ones taken in real time
situations. No modifications are made to them.
Filters:
The filters used in this study are constructed of optical precision ground and polished
German glass and is differentiated from each other by its wavelength. They appear to be black
and as a flat black glass to the human eye. Each filter has a different material thickness.
The filters used in this study are the following:
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X-Nite 330nm
X-Nite 715nm
X-Nite 780nm
X-Nite 830nm
X-Nite 1000B
X-Nite XDP
X-Nite 330nm is a UV Pass / Visible Block Filter. It has a peak transmission at 330nm
at 85%. The transmission takes place at 270nm and 375nm at 50%. There is a minor peak at
720nm which allows a small amount of visual and infrared light to pass through the filter. As
insects view their world largely in UV range, flowers look unusual under UV than under
visible light than under IR light. Another field of relevance for UV filter is in forensics to find
traces of marks or writings invisible to the human eye, which is accomplished with the use of
this filter. Another method would be to directly photograph on test object with UV light.
X-Nite filters having a cutoff at 715nm, 780nm, 830nm, 1000nm are infrared filters
blocking visible filters and allowing only infrared light to pass through. X-Nite 715nm allows
715nm through 1200nm, X-Nite 780nm allows 780nm through 1200nm, X-Nite 830nm allows
830nm through 1200nm, X-Nite 1000 allows 1000nm through 1200nm and X-Nite XDP is a
high-resolution infrared filter. The XDP filter is a different animal from the 830 and 1000nm
filters. In some respects, it is closer to the 1000nm filter but gives greater detail because the
filter has a Dual Profile light transmission curve. One peak is near 1000nm and one is much
lower. There are many fields where these filters are in use
 Infrared photography: Infrared camera film is recognized for its tremendous high speed.
Furthermore the pictures taken seem dissimilar when observed in the infrared range as
opposed to the visual range. This feature is advantageous in seeing through the clouds,
detecting forged documents and even in Forensic departments for crime scene analysis.
 Infant monitoring: This filter is very useful for a parent to view their child in absolute
darkness without any disturbance.
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The images taken by the camcorder might be slightly different from the actual images as the lens of camcorder is
coated with UV and IR block.
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 Industrial Purposes: X-Nite filters are used for factory automation and inspections to locate
faulty objects as one can see through the objects to determine invisible cracks that are not
visible to the naked eye.
 Hunting: Animals have a tendency to remain motionless when alarmed. However their
warmth shows up as the infrared light allowing the hunter to see them even at night.
 Plant vegetation and aerial photography: IR is very helpful in finding illegal marijuana
fields, charting a variety of plant augmentation and much more as vegetation looks very
different under IR.
Furthermore this filter is also used to attain some “X-Ray effects” – in that by
adding an infrared filter to the camera and operating it in daylight one can view through
certain variety or texture of clothing. This is more prominent on dark synthetic fabrics.
The following graph displays the electromagnetic spectrum and comparison of different
filters used in this study.
Figure 1 – Electromagnetic Spectrum
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Figure 2 – Wavelength Vs Transmittance graph for X-Nite 330nm filter.
Figure 3: Wavelength Vs Transmittance curve for X-Nite filters 715nm, 780nm, 830nm and 1000nm.
The table below shows the different scenarios under which targets are video captured.
SCENARIO
TARGETS
Outside/Inside People
City Streets, Animals
Greenery,
Vehicles
Open/
Crowded
space.
OBSTACLES
Doors,
Stationary
vehicles,
Buildings,
Windows,
Furniture
CLUTTER
Trees,
Buildings,
sky, clouds, sun
effects, flowers and
plants
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