Automated Photography
Also see our discussion of PIR detector characteristics.
Rain, Fog, Mist, & Frost | Reflections / Glare | Shadows | Date Imprinting | Mounting & Attachment
Sensor Range | Site Terrain | Water | Empty Images | High & Low Temperatures | Recording Site Info
Data Aquisition | Theft deterrence | Time-Lapse
NOTICE: Content from this page has been plagiarized by at least one company that sells low quality do-it-yourself camera kits.
Let's face it... you're not going to become another
Art Wolfe
by using automatic cameras. Our cameras are intended for non-intrusive
research applications - not to capture award-winning images. With that
in mind, there are ways to improve the quality of your images, making
identification of target species easier. You never know, you just might
get some nice pictures too. Below are some basic tips - send us any
that you come up with and we'll add them.
Note: While his page is aimed at still photography, many of the tips could also be applied to videography.
All of the above can cause image degradation,
or 'ghosts' that are seen in some images. A random, translucent,
milky white wash across an image is a sign of fog or mist. This
occurs when the light from the cameras flash or other light source
bounces around the water droplets that the fog or mist is composed
of. Fog, illuminated by the flash, can glow as if it
has its own light source. There is not much that can be done
to avoid this problem. You can move the camera out of bottoms
or away from pond / lakesides - but fog, mist, or low clouds
can show up almost anywhere. Try reducing the detectors
sensitivity so that your targets are closer - but that will only
help a to a certain degree.
Under certain conditions fog, mist, or moisture-saturated air can condense to form
dew, or if cold enough, frost. This can gather on the window
over the cameras lens and cause pictures to be blurry in spots
- or become partially or completely obliterated if heavy dew or frost builds
up on the lens window. Cold drops of dew running over the sensor
window can cause falsing. A heavily
frosted PIR sensor window may not permit motion to be detected at all.
Frost or dew can be hard to diagnose as problems because it has
often evaporated by the time you get out to inspect your camera. Fortunately you can do something about dew and frost!
Hoods over the lens and sensor windows will provide some protection
from the moisture-saturated air passing over the lens and sensor windows, and prevent
much of the moisture from collecting on the windows. Crow Systems offers optional hoods for our cameras. Contact us for details.
Rain can have much the same effect - cool or warm rainwater
running over the sensor window can cause falsing,
and drops on the lens window can cause blurry images. The hoods
described above will solve many rain-related problems. In tropical
areas lens & sensor hoods are almost a requirement. A product
such as Rain-ex® can also be used
to help the rain run off the lens window faster - do not use
it on the sensor window! - we do not know if the chemistry
of Rain-ex® type products will degrade
the sensor window material over time.
Notes:
The rain hoods might cause minor vignetting
of the image depending upon your specific camera system. Under
certain temperature and humidity conditions, condensation could
form inside the cameras housing. If you ever encounter
this problem, simply enclose a fresh desiccant packet inside
the housing. Various chemistry desiccants are available either
from us, or from the many suppliers of electronic / photography
equipment.
Picture mildly degraded by flash reflecting off night-time mist / fog.
This one is blurred by condensation on the lens window - also poor background.
This photo has 'the blues'. Flash refracts off night-time mist - then automatic processing adjusts improperly.
Objects that look innocuous in the daytime can, in night photos,
cause your images to be at the least unpleasant - at worst unidentifiable.
Branches, twigs, leaves, blades of grass, and assorted debris
hanging nearby in the cameras field of view can become glowing
monstrosities when illuminated at night by the cameras flash.
Some tropical species with large, glossy leaves can reflect enough light
to wash out an image completely. Place your camera trap so that no
items are hanging nearby within the cameras field of view. If
you must, trim some of the offending items out of the way.
Crusted snow and glare ice can cause much the same effect. In
snowy areas - orient your camera so that it is not pointing down
at the snow - face it parallel to the surface or up slightly.
When setting up your site, take a moment to consider where heavy flash or sun shadows may fall. This can be easy to overlook when all is fairly well lit - but at night the cameras flash can cause heavy shadows which might obscure your target. The rising / setting sun will also cast heavy shadows in unexpected places. An example in which the heavy contrast between bright and shaded areas could make target ID difficult or impossible.
The date is typically imprinted in the lower right of the image. Ensure that this spot is fairly dark in your target
area, or the date stamp may not show up. If your camera must
be used in a location with light-colored, red, or orange background,
you can devise a simple mask to darken the date imprint area.
Estimate the location of the date imprint area on the housings
lens window or camera lens. Using a Sharpie®© type marker, darken that area. The area does not need to be very large
- just a line of a medium tip marker. Make some test shots to make
sure that the positioning of the mask is correct. When no longer
needed, carefully clean the mask with a
tissue dampened with rubbing alcohol.
In film cameras, if date imprinting is weak or not functioning, check the cameras date-back
battery and program setting. The date-back battery is usually
a separate battery located within the cameras film door. Refer to the camera's instruction book for details on replacing
the date-back battery and setting imprinting options.
In digital cameras, ensure that date impring function is set ON.
Interesting information may be extracted from the EXIF image file
header.
Height: The ideal mounting height depends upon your
target species. For targets such as white-tailed deer or moose, a height
of 0.8m to 1.5m works well. For medium size mammals
and larger birds, use a height of 0.5m to 0.8m. Mount from
ground level to 0.5m for small mammals and birds. Use care
when mounting the camera in flood-prone areas. Creative camera
angles can achieve interesting effects, or help deter theft - but
always consider the target area and how the sensor will 'see'
it to try and avoid falsing. An interesting
mounting scheme is to place the camera high (>3m), and point
it down at the target area. Unusual camera angles can also help
reduce 'red or white-eye', and might prevent thieves from seeing
the camera by keeping it out of normal line-of-sight.
Stability: PIR type sensors detect movement, so a stable
base a requirement. If placed on a small tree or other
unstable mount, the unit could be moved about in strong winds
- this will be interpreted as motion by the sensor and
it will take a picture - see Falsing.
Make sure any trees you plan to attach the unit to are about
10"DBH or larger. In treeless areas, a stout stake can be
driven into the ground, or the unit can be placed directly on
the ground or on top of a rock, etc. In that case, make sure
to tether the unit to something heavy, so that no animals relocate
it for you.
With PIR sensor cameras, set a sensitivity that suits the target species and camera you're using. Try to set the camera so the target will be led across the sensor's field-of-view, and within a distance so that the target will be large enough in the image to identify. When trying to capture images of small species, set the sensitivity high, but point the camera down so that much of the sensors field of view just aims at the ground. This way the detector won't pick up larger animals that are passing by well beyond the range where your smaller target species would not be detected. To help restrict detection to larger species, point the camera up slightly so that small species will pass under the sensors field of view undetected. You can also mask your cameras sensor window to restrict the field of view pattern.
When setting up a site, consider the topography of the immediate surroundings. Ground sloping up or down can cause images of only legs or heads. Large obstacles in the image area - such as heavy brush, a fallen tree, or boulders - should be avoided, as your target might disappear behind them after being detected, but before a picture is taken. If there are obvious burrows made by various small animals, the sensor should be pointed elsewhere (unless those animals are what you're trying to get pictures of!).
PIR type sensors can be used over still, shaded waters or small streams. Large bodies of open water and fast running streams or rivers should be avoided. Moving water of slightly different temperatures can be detected and cause empty images. In large bodies of standing water, convection currents can cause changes in surface temperature, causing empty images.
Empty Images - Falsing - TopFalsing refers to images with no target visible.
The greatest down-side of the PIR sensor
is the fact that it can detect anything that is apparently moving
- air, shadows, grass, shrubs, etc - and has a temperature differing
from ambient. Many schemes have been tried to minimize this problem,
but in the harsh outdoor setting some falsing is unavoidable.
With that in mind, a PIR-based automatic camera can be a highly
versatile research tool - when properly applied. Remember
- consistent empty images are almost always caused by either
poor site set-up, or small, fast animals moving out of the area before
a picture can be taken. Please read all instructions and 'helpful
hints' sections carefully.
- Orient the sensor away from the rising and setting sun. In general, pointing the sensor North or South works well, but local conditions could dictate otherwise.
- Keep the sensor aimed at an area that will not have intense, direct sunlight warming all, or any substantial part of, the detection area. Tree or cloud shadows moving across a sun-warmed patch can cause a momentary temperature drop, which could cause a false event to be recorded.
- Do not place the sensor in such a way that bright, direct sunlight will fall on the sensor window.
- Tall, sun-warmed grasses or other vegetation blowing in a breeze can be detected. Point the sensor away from dense, sun-warmed vegetation which can trap heat.
- Even in shaded areas, keep the sensor pointed away from dense evergreen shrubs that can retain the days heat. A warm evergreen or other dense shrub will hold the days heat. The air temperature drops at night - and if the still-warm shrub is moved by wind, this movement could be detected. This usually is only a problem when temps are over ~80ºF
- If the site is known to have many small birds and/or mammals, you will surely get empty pictures, as these active, fast animals may leave the area before a picture can be taken. Set up your camera to suit your target.
- Wind (moving air) can cause falsing. The moving air may be warmer/cooler than local ambient. Choose a site sheltered from strong winds if you plan to use your PIR equipped cameras in a location prone to high-winds.
- Wind can also cause movement of the tree or other object you have your sensor mounted to. Make sure to secure your sensor to an object that will not sway markedly in strong winds. Trees should be about 10"DBH minimum.
Some examples of falsing. Sun rise/set induced - Sun-warmed areas causing falsing 1 2 3 - also with shadows.
If you are experiencing falsing with one of our non-PIR
based products, please contact us for
assistance.
Using automated photo equipment at temperature extremes requires
special precautions.
Here are some tips for using your equipment in the Cold or Hot
weather.
Life in the Cold:
- PIR sensitivity and range will increase as temperatures drop - be sure to adjust to suit your needs.
- For film cameras - use 12 exposure film. Longer rolls of cold stiffened film can put undue strain on batteries, film drive motors and gears.
- Batteries will not last as long or be able to deliver their full potential current - check and replace as needed. Note that the batteries might still be perfectly usable when the temps go back up - so don't recycle them without first testing them.
- Fresh desiccants placed inside the housing are important to help prevent potential frost-seizing of the cameras internal moving parts.
- While falsing is typically less of a problem in the cold, ice and/or snow glare and exterior frost problems will increase.
- The PIR sensor will take longer to 'warm-up' when first powered on.
- When retrieving a unit from a cold environment into a warmer
location, make sure to leave the unit closed while its internal
temperature becomes equal to ambient. If a cold unit is opened
immediately while in a warmer location, condensation can form
on the internal surfaces of the unit and/or camera - potentially
leading to damage. For best results in this situation, check
the unit as needed before bringing it into a warmer location. Leave the unit closed for at least 1 hour
while the internal temperature stabilizes.
Bearing the Heat / Humidity:
- PIR sensitivity and range will decrease as temperatures rise - be sure to adjust to suit your needs.
- Film might stick together due to humidity - causing problems such as premature film rewinding, film load failure, blotches on developed film, or camera error messages (refer to camera instruction manual).
- Keep film stored properly before use, and use fresh desiccants to help keep camera interior dry. Shorter rolls of film changed out more often can help minimize film-sticking problems.
- Sun-heated shrubs, branches, and moving air can cause excessive falsing- particularly in the heat-of-the-day. If you are having this problem, relocate to a different site, or set the unit to 'night-only' mode, or contact us about high temperature auto-disable options.
General high and low temperature considerations:
- When moving your unit from one extreme to another (hot to cold or cold to hot), a PIR sensor equipped unit will require time for thermal stabilization. Until the internal temperature of the PIR sensor equals the ambient temperature, you might experience unexpected results such as falsing and/or decreased detection distances.
- For best results when moving the unit between temperature extremes, allow at least 1 hour thermal stabilization time.
Make a page size card with your site number, placement date,
user identification, and any other applicable information for
each camera trap site. Place the card in the center of your site
area and take a photo of the card. This way you'll have a hard-copy
of site information for future reference. Fold the card and put
it inside the camera unit - maybe along with a brief description of
your study and contact information - this might help prevent
vandalism or theft. Using a weather-proof holder, you could also
leave the card in the target area to have site info saved on
every image. Color-coded flagging tape could also be tied in
the target area to color-tag each image.
Check with appropriate Federal, State, and Local law enforcement offices to ensure
that use of the equipment is permitted in your planned target area.
Secure all required permits and/or permission before placing any
equipment in the field!
Collecting Data - Time, Temp, Humidity, Light, etc - Top
Crow Systems offers a variety of optional data collection
tools to record site environmental conditions. While these tools
ease statistical analysis of data, they tend to be fairly expensive.
Useful information can also be gathered with low-cost, low-tech, and readily
available equipment. For example, temperature, humidity, or time
can be acquired by placing a large display thermometer, humidity
meter, or clock within the cameras field of view. With a digital
camera and a large memory card, these methods could allow site conditions to be recorded
periodically to examine environmental trends at your site. Snow
or water depth could also be charted in a similar manner with
the use of a measuring pole.
With a little imagination, the possibilities of these low-tech
means of data collection are vast.
By far the best way to prevent theft is to keep the equipment from being found in the first place. No chains, cables, or straps will stand up to bolt cutters, hacksaws, or a slug from a gun. But if they can't find it, they can't take it!
- Make or buy a camouflage cover for your equipment. Match
the immediate environment and/or season. It does not have to be pretty
- you just need to disrupt the hard lines and colors of the equipment.
NOTE: painted or 'dipped' camouflage patterns look pretty on the shelf - but they are
not as effective pattern disrupters as the loose-fitted cover or bag-type
camouflage.
- Do NOT just plunk the equipment down in an easy to reach spot such as a trail side - go for more difficult locations - thieves a are lazy bunch - that's why they steal.
- Think like a killdeer - do a distraction display! Place an eye-catching item - anything highly visible and out-of-place - in such a manner as to distract attention and draw the eye away from the equipment. Hopefully by the time a person has investigated the 'distraction' item, they will have passed by the equipment.
- Do NOT ever leave a flagging tape trail leading directly to your study site!
- Place an informational card describing the nature of your research inside or on the equipment. Many pieces of equipment are stolen or vandalized out of spite for what the person thinks the equipment might be set up for (i.e. hunting/trapping).
- And an unfortunate one - Do NOT tell anyone who does not asolutely need to know, where the equipment is located! Much thievery is carried out by people you know.
- As a last line of defence, some form of security lock - either homemade or purchased as an option - can be used. No lock will not stop a dedicated thief. Locks will generally only deter the casual or opportunistic thief.
- Set up your equipment in such a way as to prevent movement of the camera between frames. The camera should be mounted on a rigid base free from vibrations. For added vibration / movement resistance, the equipment could be taped down with duct tape (do not cover up any lens or sensor openings!).
- Try to place the equipment where the environment will remain fairly consistent. Obviously lighting will change throughout the day, but you can avoid sudden changes from heavy shadows, etc with thoughtful placement.
- For close-up work in a controlled environment, try to keep your lighting consistent. Note that some lamps generate fairly large amounts of heat, and some means of venting excess heat might be needed. Fluorescent desk lamps, lower power incandescent bulbs, or microscope lamps offer a lower heat alternative, but may require filters to compensate for color temperature. If using a flash, a low-power setting might be best for close-up work.
- Compose your target area so all parts of the subject are visible, and there are no distracting background elements. Composition is very important when images will be compiled into a movie format. Take some test pictures and review them to check the composition. Make any needed adjustments to the camera and control system settings.
- Estimate the time interval between frames. Do a trial run or observe the rate of change. Calculate how many frames should be needed from beginning to end, and determine if the capacity of your storage media will suffice. Allow around 10% more storage than calculated.
- Begin the sequence before any target activity starts, and let the camera continue capturing frames while after the target event terminates.
- For events that take place over a long period, check the equipment and subject at regular intervals.
"Who would believe that a small scene of nature could contain the images of the universe?" - Leonardo da Vinci
|
|
 |
WHY? - To find out,
visit http://www.glassdog.com/smarttags/index.html |