Night Vision Security

Honeywell Night Vision Security

2HONEYWELL - CONFIDENTIAL File Number

Most crimes happen at night – the challenge to the security professional is to ensure the video footage is effective on a 24/7 basis, 365 days a year. Night Vision is fundamental to achieving this.

Wikipedia describes Night Vision as: “The ability to see in a dark environment. Whether by biological or technological means, night vision is made possible by a combination of two approaches: sufficient spectral range, and sufficient intensity range. Humans have poor night vision compared to many animals. Animals can see well into the infrared and/or ultraviolet compared to humans.”

This brings us to:

To address the challenges most experienced by most low lux cameras today we adopted the Johnson Criteria to describe night vision performance. The criteria provides end users a standard framework for evaluating night vision performance.

What is Night Vision Security?

The myth of the “low lux camera”


Detection, Classification, Recognition and Identification

•Detection: A human-sized object is simply determined to be present

•Classification: An object is determined to be human as opposed to an animal or other object.

•Recognition: A human-sized object is determined to be a threat or non-threat based on the type of clothing worn, equipment carried, etc.

•Identification: A human-sized object can be positively determined to be a specific individual.

Security professionals can easily achieve outstanding night vision if they understand infrared illumination. To solve the problem, night-time performance parameters must be clearly defined up front: What is the camera trying to detect? Below are four simple classifications (DCRI) which can help define customer expectations:

Standard framework for evaluating night vision performance


Introduction to CCTV lighting - What is light?

Light is fundamental to any CCTV camera sold today. Without light no images are possible, as it is light reflected from the world around you that makes the world visible—both to the human eye and to the CCTV camera.

Light determines whether a subject can be viewed at all, at what distances. The quality and direction of the light controls the appearance of the subject.

Light is energy in the form of electromagnetic radiation. The wavelength of light (also known as frequency) governs the color and type of light. Only a very narrow range of wavelengths from approximately 400 nm (violet) to 700 nm (red) is visible to the human eye. However, CCTV cameras can detect light outside the range of the human eye allowing them to be used not only with white light but also with infrared (730-110 nm) for night-time surveillance.


Difference between white and infrared light?

White light: various light sources from 400-700 nm• Use cases:

- Illuminate an area for the CCTV system- Improve the overall level of illumination for key personnel- Provide a welcoming environment for authorized personnel- Deter crime by illuminating a secure area on intrusion- Can be used with monochrome, color and day/night cameras

Infrared- 715-730 nm: Overt IR, produces a soft red glow- 815-850 nm: Semi-covert IR, produces a faint red glow just visible to the human eye- 940-950 nm: Covert IR, invisible to the human eye

• Use cases:- Provide discreet or covert illumination for CCTV cameras- Minimize light pollution- Provide very long-distance illumination- Can be used with monochrome and day/night cameras


Let’s talk about infrared illumination…

• The main problem in designing a CCTV system when incorporating infrared illumination is that infrared light cannot be measured in lux.

• How do you specify camera sensitivity?

• How do you know what will be seen at various distances?

• How sensitive are different cameras to infrared light?

• How are spectral diagrams to be interpreted and the effect of the lens?

How far does your light shine?


Basic understanding of infrared illumination

• Infrared illumination is used to provide light over scenes that would

otherwise be too dark for a camera to capture an image. It is a

compromise, because the best results can only be obtained by

providing sufficient white light but of course this is not always possible.

In many cases, using powerful floodlights would cause a considerable

nuisance and could be dangerous where there is road traffic moving

toward the lights. It is also difficult to cover a large area when a pan/tilt

camera is being used. In this case, illumination is only required where

the camera is directed, and infrared lights provide the answer.


What is infrared light?

Infrared light is a light that the human eye cannot see, but the monochromeCCTV camera can. Near infrared light is light of a longer wavelength thanthe visible spectrum, between 700 and 1,100 nm, just beyond the visiblespectrum. It is this near infrared light that is used for CCTV purposes.

As infrared light contains none of the colors visible to humans it cannot be usedwith color cameras. To see infrared light, monochrome or day/night camerasare needed. CCTV cameras using infrared light always provide monochromeimages.

Applications that require covert surveillance, or applications where even lowlevels of overt lighting must be avoided for reasons of light pollution, are idealfor infrared light.


What is infrared wavelength?

Infrared light is a light that the human eye cannot see but that a monochrome CCTV camera can. Near infrared light is light of a longer wavelength than the visible spectrum. Itis this near infrared that is used for CCTV purposes.

• 380-750 nm are the wavelengths of light that are visible to the human eye.

• When all these wavelengths are seen simultaneously, the eye cannot distinguish the individual wavelengths and the result is seen as white light.

• Therefore, white light is not one wavelength but a combination of them all.

• Infrared wavelengths range from 730-1100 nm.

• Typically, our product operates at the 850 nm range which emits a dull red glow. It is semi-covert and is the most common type of LED infrared wavelength.

• Note the charts on slides 12 and 13.


How does infrared work?

Infrared waves travel in a straight line but can be affected by:

• Reflectance—the reversal of direction that occurs at the surface of an object, i.e., a mirror.

• Refraction—a change of the angle that occurs at the boundaries of different surfaces. Different wavelengths have different angles of refraction, i.e., a stick apparently bending in the water.

• Diffraction—a deflection that occurs at apertures or edges of objects.

• Absorption—color surfaces absorb some light and reflect the remainder. A black surface absorbs most of the light falling on it. Light energy is usually turned into heat, so dark materials heat up easily.

• Visible radiation (visible light)—the range in which the sun and stars similar to it emit most of their radiation.

http://en.wikipedia.org/wiki/Sun

http://en.wikipedia.org/wiki/Star


Understanding reflectance and absorption

Reflectance: When light hits a surface it can be bounced back as reflection. The quality of the surface impacts the type of reflection. Highly textured surfaces scatter light due to tiny irregularities in the surface material, while flat surfaces such as a smooth white painted cementwall could provide a more focused reflection.

Absorption: Some surfaces actually absorb light. Colored surfaces absorb some light and reflect the remainder. A black surface absorbs most of the light falling on it. The light energy isusually turned into heat, so dark materials heat up easily. For example, black paint will absorb light but a white colored cement wall could reflect approximately 40-50% light back to the

source.

IR Light

Absorption

Reflectance


Typical reflectance levels

Reflectance is a measure of light reflected from surface/light incident on surface. The energy that is not reflected is absorbed and converted to heat. Low-reflectivity objects absorb a lot of energy – hence the reason asphalt feels warm. The table below shows some everyday objects and their level of reflectance:

Material Typical Reflectance (~%)Snow scene 85%

Standard white paper 75%

Aluminum 75%

Glass windows 70%

White cloth/fabric 65%

Concrete (new) 40-50%

Plasterboard 30-60%

Open country (trees/grass) 20%

Brickwork (new) 10-30%

Brickwork (old) 5-15%

Concrete (old) 5-15%

Empty asphalt area 5%

Materials have different reflective levels with white light and infrared light. For example, trees and grass have a very high level of reflectance to infrared light.


Visible light – what the human eye sees

Human vision is confined to a small portion of the electromagnetic spectrum called visible light. Below shows the spectral response (visible light) of the normal human eye with luminous to radiometric conversion:

Visible light color spectrum

http://en.wikipedia.org/wiki/Electromagnetic_spectrum

http://en.wikipedia.org/wiki/Visible_light

http://en.wikipedia.org/wiki/Visible_light


Electromagnetic spectrum: visible and infrared light

730nm 1100nm

InfraredVisible Light

RadioRadioX-RayGamma Ray

Electromagnetic Spectrum

what the human eye seeswhat the camera seeswhat the camera sees


Visible light, also known as “white light”Measurement of white light on a scene can be simply recorded by use of a light meter. White light is measured in lux, the European standard. It is the level of illumination produced by one lumen over one square meter. In North America the foot candle is still widely used as a unit of measurement. Typical lux light levels are:

Bright Sunny Day = 10,000-100,000 lux

Overcast Day = 1,000-10,000 lux

Twilight = 1-100 lux

Street Lighting = 5 lux

Full Moon = 0.1 lux

Bright, Clear, Starlight = 0.01-0.0001 lux


Example of indoor IR camera performance

What to expect? ~ 375 lux scene

True Day/Night, 20 LEDs True Day/Night, DNR, 18 LEDs

Describing night vision performance effectively has long been a deeply confusing subject in the security industry.

Always remember, different applications require different levels of night vision performance.•

Object is ~38ft away from the cameraBack door is ~ 70ft

Object is ~38ft away from the cameraBack door is ~ 70ft


Example of outdoor IR camera performance

What is light? Light and surface?

~ 16K lux scene True Day/Night, 48 LEDs

No external lighting in scene – only IR lightingFront of bear den pond ~65ft away from the camera

Light is fundamental to CCTV. Without light no images are possible as it is light reflected from the world around you that makes the world visible both to the human eye and to the CCTV camera.

To control lighting, you must understand how light changes in quality and direction when it meets a surface. The three main effects are diffusion, reflection or absorption. Often, light is affected by a combination of these effects, and all influence the quality of CCTV lighting.


Primary considerations for selecting IR cameras

• The lens/focal length- F-stop/aperture: The aperture or f-stop of a lens determines how much light passes through it to the

camera chip. In simple terms, the lower the f-stop, the more light the lens passes.

- Aspherical lenses provide improved low-light performance.

• Range or distance to the object: - The maximum illumination is at the center of the beam of light. This falls off toward the furthest

extremity. Even levels of illumination is key:

• Image quality that is affected by the signal level received at the CCD sensor.

• Performance parameters must be clearly defined up front: What are the customer’s expectations?

- Detection? Classification? Recognition? Identification?


Primary considerations for selecting IR cameras

• Spectral response of the camera. The higher the spectral response, the better the picture. Below are two examples:

• True Day/Night (TDN) or Software Day/Night (SDN)?- TDN uses a removable infrared cut filter in color mode and an optical low-pass filter

(OLPF) in black and white mode, guaranteeing optimal image quality at any time of day and good quality color rendering.

- SDN does not use a removable infrared cut filter but typically uses an infrared notch filter. Depending on the spectral response, low light sensitivity and daytime color rendering are not as good as TDN.


Practical installation considerations

Infrared and focus shift - Focus shift is a potential issue encountered when setting up camera systems for 24-hour performance using infrared. The different wavelengths of visible l400-700 nm) and infrared (700-1,000 nm) light create different focus points throughthe lens onto the camera chip. This can lead to a loss of image focus at night, particularly if the camera is set up during daytime operation. The degree of focus shift depends on a variety of factors:• Lens quality• Wavelength of the infrared light (longer wavelengths such as 950 nm will provide a more

exaggerated focus shift)• Infrared response of the camera

Focusing the camera correctly for low light performance means the camera will be focused for infrared with the aperture fully open. During daytime operation, the increased depth of field created by a closing aperture will counter the effects of focus shift. The best solution isto focus the camera using only infrared lighting. This can be achieved by:• Setting up the camera at night using infrared lighting• Using an infrared pass filter over the camera lens to simulate a night-time scene


Questions?

• If you have questions or would like additional information, please contact Honeywell Inside Sales at 1-800-796-2288.

Night Vision Security

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Transcript of Night Vision Security