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Positioning a weather web-camera

This section describes some of the real-world considerations that should be made when locating a weather web-camera. This includes envionmental factors, positioning for maximum impact and, some legal thoughts.


Location Location Location

A weather web-camera should be located with a clear and uninterrupted view of the sky. However, how that view changes throughout the day and, over the whole year, is an important consideration. Some questions to ask: Is one part of the sky more active than others? Do more interesting clouds build a particular direction? Are spectacular sunsets or sunrises more likely to occur in one season rather than another? Does one direction have an appealing landscape to set the clouds against? A weather web-camera location is often a compromise, so a number of candidate locations should be given due consideration. A weather web-camera is not strictly restricted to just one view all year round; so the web-camera could be redirected or even relocated over the course of a year to capture the most favourable weather action.

Picture of a sketch of the active sky
Creating a plan of the local site will show where and when the most interesting weather
action is likely to happen. This will also outline where there are obstructions to the scene.



Sun awareness

It is essential to consider where the Sun is going to be in the web-camera's frame. This is not just for artistic composition, but there are implications on exposing a web-camera to excessive levels of light and heat. Sunlight beaming into a web-camera's lens can degrade the performance of the imaging chip. A weather web-camera is likely to be fixed onto one view 24-7, which means the Sun could remain in frame for two to three hours at a time. Furthermore, as the seasons change, so will the position and intensity of the Sun.

Most brands of brands of web-camera are tolerant of the Sun being in frame due to the wide angle nature of their lenses. Fitting a telephoto lens will exponentially increase the chance of damaging a web-camera if the Sun passes across the frame! Sun damage is more likely at lower latitudes where sunlight is stronger but, the Sun is more likely to climb out of frame sooner. At higher latitudes, the Sun is more likely a hazard in the late spring and early autumn when it still has strength, but is low enough to shine directly into the lens.

Picture showing the suns path throughout the year
In the winter months, the setting Sun unobtrusively transits the side of the frame. However, as the year goes on, the Sun intrudes ever higher into the frame and, it becomes stronger. Between the spring and autumn equinoxes though, the Sun passes safely over the top of the frame.



Temperature and humidity

Ambient temperature and humidity have implications for a web-camera. The ambient temperature range inside a typical home is from ten to thirty degrees centigrade (50-86°F). On a window sill, this range expands from zero to forty degrees Celsius (32-104°F). Add on a web-camera's own heat output of some twenty degrees Celsius (68°F), and on a summer's day, a web-camera located on a window sill could easily go outside of its operating temperature of around fifty degrees Celsius (122°F). As a general rule, locations exposed to the Sun from midday through to mid-afternoon should be avoided.

Overheating is likely to cause a non-fatal malfunction, but in extreme cases, the web-camera may lose its firmware and become a pricey paperweight. Where extreme heating conditions are likely, a small blower fan can be fitted to cool the camera. But in practice this will only lower the temperature to some five degrees Celsius (9°F) above the ambient temperature.

A location that seems right during the daytime may overnight, become cold and damp. The frequent build up of condensation will corrode connectors and fixings, and bring about the inevitable a build up of mould. Leaving a camera switched on overnight throughout the cold winter period may help to avoid the affects of condensation and possible frosting.

High humidity environments such as those found in the tropics will cause web-cameras to deteriorate due to corrosion and bio-chemical reactions. Where a location contains corrosive aerosols, such as the salt in a maritime environment, even a web-camera mounted inside will experience corrosion of connectors and even circuit boards. In these circumstances, an external camera enclosure may be required inside.

A good location gives the best view, but places the web-camera under the least stress.

Picture of an enviroment resistant camera housing Where a web-camera is likely to be exposed to environmental stress, some form of protective enclosure should be considered. Even if the web-camera is located inside a building.


Zoology
 
Picture of a creepy thing Ventilation slots in most cameras are made to let heat out, but they will also let dust in. In dusty environments, web-cameras should be shrouded, but not in such a way as to cause overheating.

Insects may set up camp inside the cosy warm electronic box that is a web-camera. Spiders have a habit of spinning webs across the front of web-camera lenses, which may put some people off revisiting a web-camera forever!

Inquisitive rodents might want to gnaw parts of a camera, especially the interconnecting cables.


Lenses

The interesting part of the sky can often occupy a significant proportion of the horizon. Which means for a weather web-camera trying to capture weather phenomena, a wide angle lens is most desirable.

Most IP cameras are designed for the surveillance of work stations, stairwells, etc, and are supplied with lenses that are slightly wide angle. This equates to roughly one eighth of the turn of a compass; for example, with a camera pointing west, the edges of the frame will be inside the south western and north western horizons. Desktop USB webcams have wider angle lenses because the subject (a person sat at their PC) is only inches from the camera. These wide angle lenses cover a lot of sky, for example from the south west to north west horizons, but the wide angle lens may cause pin-cushion distortion which can make clouds look small and the sky unnaturally curvy.

Extra ultra-wide-angle lenses can be purchased for web-cameras separately, but these are vendor specific and often require disassembly of the web-camera to fit them. Furthermore, the wider the camera lens, the smaller clouds become; an attractive cumulus may turn into an indistinct white blob. A fish-eye lens gives a dramatic 360 degree view, but the detail contained within, especially around the horizon, will be of little use to anyone.

It is possible to fit any kind of lens to a web-camera. However, the tiny size of an imaging chip will often fail to cover the image field of the ad-hoc lens, turning the web-camera into what seems like a telescope! This is especially true when fitting 35mm format lenses to web-cameras. Furthermore, imaging chips are sensitive to infra-red wavelengths. Which is why all web-camera lenses are fitted with an infra-red blocking filter. Fitting an ordinary filter-less lens to a web-camera will result in some very bizzare pastel green and blue hues.

Picture of field of view
Simulated, the greater the field of view of a lens, the worse the distortion of the scene. The 70 degree scene is typical of a USB webcam, whereas the 45 degree scene is typical of an IP camera. A slightly-wide angle lens with a field of view from 45 to 55 degrees gives the most information about the sky with the least distortion.



Setting the scene

A well positioned web-camera respects the rules of composition. Exclude from the scene where possible, close-in distractions like street lights, cables, poles and aerials, as these may dominate the scene. In most urban environments some of these distractions are unavoidable. Buildings, rooftops and distant hills add a sense of perspective and depth to an image. Trees in frame will provide a sense of season, even when bare or covered in snow. Horizons should be horizontal; a wonky web camera makes it seem the web master neglected to straighten the camera after it was knocked awry! A web-camera scene that is pleasing to the eye will always bring repeat visits to a web-camera homepage.

Picture of rooftops Rooftops and hills create a sense of depth Picture of an obstructed scene Avoid close-in distractions
 
Picture of a wonky horizon Wonky horizons are just annoying Picture of a tree in fall Deciduous trees can give a sense of season


Revealing the sky

The sky always looks bigger when the scene includes a horizon; take away the horizon, and the effect of perspective and therefore, the perception of the size of the sky is lost. Typically, the landscape part should occupy between one fifth and one quarter of the frame. For a landscape web-camera, this becomes one half to two thirds of the frame.

Below the camera is pitched up too high. There is no sense of scale.
These clouds could be huge or tiny.


Picture of scene pitched too high

Below this is about right for a weather-camera.
The buildings and horizon set the sky in context.


Picture of scene pitched about right

Below the camera is pitched down too low.
The weather is lost. This is now a city-cam.


Picture of scene pitched too low



Filters

A landscape photographer will know a sky can be made a deeper shade of blue and clouds made to stand out with the use of a polarising filter. However polarisers are expensive and, given the tiny size of the filter required for most web-camera lenses (no more than quarter of a square inch), a photographic grade multi-coated filter is excessive. There are other sources of cheap polarising filters which include, children's polarising sunglasses for £1($2) and, recommended, the linear polarising filter strip that covers the LCD display in a redundant pocket calculator. These can be attached in front of the lens using ingenious means - tape.

The angle at which to set the polarising filter should be experimented with throughout the day. Polarisation works best when the Sun is at right angles to the subject; so with the Sun at at midday, the sky to the east and west will polarise the best.

A polarising filter also provides a degree of neutral density, which reduces the amount of strong sunlight entering the web-camera; which is a good thing. Filter types such as ultraviolet and skylight are generally unnecessary for weather web-camera operation. Coloured filters can be experimented with for special effects!

Picture of polarisation effect
The effect of polarising the sky can range from insignificant to dramatic!



Legal Considerations

Some points to consider when locating a weather web-camera service:

  • Never point a web camera directly at someone's residence. Not only is this discourteous, but the residents may have a prima-facie claim that you violated their privacy by broadcasting their daily activities to the web. Be courteous to neighbours and frame the image in such a way that any window of any property occupies just a few fuzzy pixels around the edge of the frame. After all, the sky is the action, not the bedroom window across the block.
  • There should be no issue with including buildings that are in clear public view from a public right of way such as houses, office buildings and factories, provided they are not made the subject of the frame and, the resolution of your image is such that no useful information can be gleaned on road names, house numbers and car registration plates.
  • However, even though they may be in full public view, avoid broadcasting views of banks, government buildings, school playing areas and military installations! Show roof tops; this is a weather web-camera.
  • Be prepared to reposition a camera only if a resident has reasonable grounds to raise an objection. Some people believe they have cart blanch to complain about everything in their neighbourhood.
  • There is a Duty Of Care when locating a web-camera, so avoid causing hazards to public safety both in public and private places.
  • There is precedence for web masters being asked to shut down webcams because they do not have the rights to transmit an event; such as a street music festival happening outside their window. In these circumstances, it may be a reasonable request if the web-camera is streaming live video and audio and, the event is not in clear public view. But this would be a most unreasonable request for a weather web-camera.
  • Web cameras in public places can be abused by the public. Displays of disorder and indecency are not unheard of. Unlikely to be an issue if a camera is pointing at the sky.
  • Disclaim. State, this web camera is for monitoring the weather and is not intended for the surveillance of persons or places, and ensure the camera is pointing at the sky.
Picture of a bad banner advert Some web sites offer credit card webcam content. The purpose of these web sites is fairly blatant to anyone seeing their search engine listing. However, disguising a voyeuristic service as something else in the hope of catching clicks from unsuspecting persons, including minors, will certainly get the web master noticed; by angry parents and law enforcement agencies!


Picture of the copyright symbol By International Treaty, the copyright of a weather web-camera's image, and the supporting homepage, is implicit. This means a copyright symbol does not have to be shown, but it is always a good measure to add a © symbol to a web page; some people assume that because something is on the internet, it is somehow public property.
If a web-camera supports on-image text, then add (c) to the title.

Despite copyright rules, some third-party webmasters will intentionally breach copyright and cherry-pick parts of another web site. Often, they will copy entire tracts of someone else's content and publish it as their own work - with a © symbol!

With dynamic content such as web-camera images, unscrupulous web-masters will often hot-link their web page to use someone else's image from a different server; and then imply the web-camera image is theirs! Be aware of abnormal activity in the Server Log; a file that records all internet transactions. The referrer for all image accesses should relate to the homepage of the web-camera service. If it refers to another web site, hot-linking may be happening. In such a case, send a courteous email to the offending webmaster asking them to cease hot-linking or, take counter measures, like changing file names.


Summary
  • Know where the active sky is most likely to be
  • Know how the position is affected by heat and light
  • Consider more than one position throughout the year
  • Avoid the midday Sun to avoid overheating
  • Avoid condensation and frosting
  • Avoid dust
  • Avoid pesky varmints
  • Consider more than one location
  • Seek a pleasing view
  • Include objects that give a sense of perspective
  • No more that one third of the frame should be landscape
  • Keep horizons horizontal
  • Avoid close-in distractions
  • Include trees
  • Polarise the sky
  • Do not invade privacy
  • Be aware of content piracy
Web-camera types Mounting a weather web-camera