LundyCam - technical information

Technical summary

LundyCam is actually 2 cameras, one with a telephoto lens ('LundyCam') , the other with a 'normal' lens ('LundyCam-Wide'). The telephoto camera shows the southernmost kilometre of the island in detail. The other camera shows the whole island and an area of the north Devon mainland.

The telephoto camera is based on a network camera. The camera PCB was removed from its plastic casing and put into an aluminium enclosure. This camera currently uses a 135mm lens (designed for a 35mm camera), giving 15x magnification. An IR-cut filter from Edmund Industrial Optics is installed between the lens and the CMOS sensor to correct the colour balance and prevent IR-radiation from reducing the sharpness of the image. Most off-the-shelf network cameras have a filter built into their standard lens for this purpose.

The wide-angle camera is currently a Compro IP70, which has megapixel resolution.

Images are captured, processed and time-stamped by a Java application written using Sun's Java Media Framework.

Outdoor air temperature at the camera location is measured using a Dallas Semiconductor DS1621 sensor, which has 0.5°C resolution. This sensor uses the I²C bus, and is interfaced to the PC's serial port by a circuit based on Alberto Ricci Bitti's pcTHERM design. A Java application on the PC communicates with the serial port using the RXTX library. The sensor is located in shadow about 5-metres above ground level, near the top of a WNW-facing wall. This location certainly doesn't meet World Meteorological Organization specifications, but so far the measured temperature has stayed within 2°C of other air-temperature thermometers in the area.

Geographical details

This scale map shows the location of Lundy Island and the webcam relative to North Devon and Great Britain. The camera is located halfway between Barnstaple and Bideford, at about 110 metres above sea level. This region is prone to sea-fog, so the island is only visible during approximately 30% of daylight hours.

Change log

	31 January 2009 The indoor Lundycam-Wide camera is replaced with an Axis 206 camera, to improve picture quality.
	9 October 2006 A sensor measuring external air temperature is added.
	16 July 2005 A 135mm lens is fitted so that more detail can be seen. The temperature within the enclosure is becoming a matter of concern. The camera and its power supply dissipate around 10 watts, and during the summer solar heating is an issue as well. A max-min thermometer was fitted in May, and has so far recorded temperatures in the range 10°C to 45°C.
	1 May 2005 A rapidly growing Horse Chestnut tree in front of the camera blocks the view, so the telephoto camera is moved to an outdoor enclosure in a position with a better view. The existing 70-210mm zoom lens is replaced with a 50mm lens, the wider field of view being useful now that a wide unobstructed viewing arc is available.
	30 April 2004 The existing single camera is replaced by a pair of cameras - a telephoto camera and a camera giving a normal view.
	5 March 2004 The Java code is changed to reduce visible noise. The main noise sources are probably the webcam's MPEG codec (during daylight hours) and thermal electrons in the CCD (at night). The new code works by averaging a variable number of consecutive frames to build each image. The number of frames averaged is adjusted according to the estimated level of noise in a test frame.
	31 January 2004 An IR-cut filter from Edmund Industrial Optics is installed between the lens and the CCD (off-the-shelf Toucams include an IR-filter, but it is permanently attached to the Toucam lens, which is not used by LundyCam). This results in a sharper image and better rendering of greens. The green/blue-boost software filter is removed. The visibility-estimation software is improved.
	9 January 2004 The existing PC (a 266MHz Pentium II) is replaced with a slightly more powerful one (a 450MHz Pentium II). This allows the image resolution to be increased to 640x480 pixels without overloading the CPU. A Java-generated timestamp is added to the bottom of each image. A green/blue boost filter is implemented in software to correct the poor rendering of green vegetation in the images. Alpha version of visibility-estimation code is installed.
	25 December 2003 The zoom lens is replaced by a 50mm f1.7 lens, which gives better image quality and allows a larger portion of the island to be seen. The aperture is set at f2.8.
	October 2003 LundyCam goes live, based on a modifed Philips Toucam Pro. The image resolution is set at 320x240 pixels. A 70-210mm zoom lens is used, set at 100mm, with an aperture of f8.