Customary units of measurement in the United States | Units of luminance
A foot-lambert or footlambert (fL, sometimes fl or ft-L) is a unit of luminance in United States customary units and some other unit systems. A foot-lambert equals 1/π or 0.3183 candela per square foot, or 3.426 candela per square meter (the corresponding SI unit). The foot-lambert is named after Johann Heinrich Lambert (1728–1777), a Swiss-German mathematician, physicist and astronomer. It is rarely used by electrical and lighting engineers, who prefer the candela per square foot or candela per square meter units. The luminance of a perfect Lambertian diffuse reflecting surface in foot-lamberts is equal to the incident illuminance in foot-candles. For real diffuse reflectors, the ratio of luminance to illuminance in these units is roughly equal to the reflectance of the surface. Mathematically, , where is the luminance, in foot-lamberts, is the illuminance, in foot-candles, and is the reflectivity, expressed as a fractional number (for example, a grey card with 18% reflectivity would have ). The foot-lambert is used in the motion picture industry for measuring the luminance of images on a projection screen. The Society of Motion Picture and Television Engineers (SMPTE) recommended, in SMPTE 196M, a screen luminance of 16 foot-lamberts for commercial movie theaters, when measured "open-gate" (i.e. with no film in the projector). (Typical base density of 0.05 yields peak white of about 14 fL.) The current revision of SMPTE 196M specifies 55 candela per square meter (nits). The foot-lambert is also used in the flight simulation industry to measure the highlight brightness of visual display systems. The minimum required highlight brightness varies based on the type and level of (FSTD), but is generally 3–6 foot-lamberts for most devices qualified under Federal Aviation Administration (FAA) or Joint Aviation Authorities (JAA) regulations. Military specifications for illuminated switches, panels, and displays, such as MIL-PRF-22885 and SAE AS7788, also require luminance measurements in foot-lamberts. Luminance levels can vary from hundreds of foot-lamberts for sunlight readable switch displays per MIL-PRF-22885 to only a few foot-lamberts in night conditions for panels in accordance with SAE AS7788. (Wikipedia).
From playlist 'Sleeping Sun' videos.
From playlist 'Sleeping Sun' videos.
Themes in the Merchant of Venice
From playlist Merchant of Venice
EEVblog #967 - Mystery Teardown
Another mystery teardown. Forum: http://www.eevblog.com/forum/blog/eevblog-967-mystery-teardown/ SPOILER: A Philips PM5639 Colour Analyser Teardown EEVblog Main Web Site: http://www.eevblog.com The 2nd EEVblog Channel: http://www.youtube.com/EEVblog2 Support the EEVblog through Patreon!
From playlist Teardown Tuesday
Why do Some Species Thrive in Cities?
Urban development can be tough on wildlife. But some plants and animals are adapting to our cities in surprising ways. Thanks to squarespace.com for supporting this video. Go build a website! http://www.squarespace.com/minuteearth (use your 10% discount code: EARTH) Please support Minut
From playlist Connecting with Nature Around You
Press F to pay respects to Papa Lambert [ integral W(1/x^2) from 0 to infinity ]
Merch :v - https://teespring.com/de/stores/papaflammy Help me create more free content! =) https://www.patreon.com/mathable Gaussian integral: https://www.youtube.com/watch?v=g-Et3vIbJdE Hypervolume integral: https://www.youtube.com/watch?v=b-u-ML8PQeo Welcome back dudes and dudettes :v
From playlist Integrals
From playlist Music.
x^y=y^x and its Amazing Solutions.
Support the channel by signing up on Brilliant for FREE using the link https://brilliant.org/FlammableMaths ! =D @FlammableMathsTwo69 Gone Wrong Done Right Playlist: https://www.youtube.com/playlist?list=PLN2B6ZNu6xmekOYxY25OQcaG_nkmw1hKv Lambert W: https://youtu.be/CX-5orQxNAg Today we
From playlist Mathematics Gone Wrong Done Right
Pi is IRRATIONAL: animation of a gorgeous proof
NEW (Christmas 2019). Two ways to support Mathologer Mathologer Patreon: https://www.patreon.com/mathologer Mathologer PayPal: paypal.me/mathologer (see the Patreon page for details) This video is my best shot at animating and explaining my favourite proof that pi is irrational. It is
From playlist Recent videos
The Lambert W Function's Derivative
Merch :v - https://teespring.com/de/stores/papaflammy Help me create more free content! =) https://www.patreon.com/mathable Let us calculate this bad boi's derivative using implicit differentiation. Also providing you with a graphical representation to show you, in which situation said d
From playlist Random problems
Review: Seapower States by Andrew Lambert
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From playlist The Bookshelf
From playlist BeDMaSH
Integrating the Lambert W-Function
Merch :v - https://teespring.com/de/stores/papaflammy Help me create more free content! =) https://www.patreon.com/mathable Integrate Inverse: https://www.youtube.com/watch?v=sejU9qnRcRE This is like ,,Part 2" of my series where we are going to be discussing some things revolving around
From playlist Integrals
2 different exponential equations
We will solve 2 different exponential equations: x^2*e^x=2 and x+e^x=2 by using the Lambert W function. Solving equations with Lambert W functions, Lambert W function Intro: https://youtu.be/sWgNCra93D8 Derivative of Lambert W function, https://youtu.be/LyEPB6Wxc_U Solve x*e^x=1 by using
From playlist Lambert W Function
Come be bored with me...and math! (The Dream Stream)
Fielding questions from my subscribers! Can you figure out any patterns in the coefficients from the end of the stream? Stay tuned for more videos soon!
From playlist Quarantstreams