Talk:Radiance

message: How does this fit in with Luminance? 5:22a 19 Apr 2007 (UTC)
: Luminance is how much the human eye responds to the radiation. The radiation may be in the infrared, and have a lot of radiance, because it carries a lot of energy, but it will have zero  luminance, because the human eye cannot see it. PAR 06:37, 21 April 2007 (UTC)
replies: text:  This sounds incorrect. Both have to do with visible light. 155.212.242.34 20:37, 4 December 2007 (UTC)
replies: text: No, PAR is right, although his answer is perhaps not clear enough. Radiance is a physical measure of the radiation, independent of wavelength. It doesn't have to be visible light. Luminance is just radiance "multiplied" by the response of the human eye. As an example, suppose you have three sources that emit the same radiance, but one is monochromatic green light, one is red light, and the third is infrared light. The second source will have lower luminance than the first, because the eye's response to red is less than to green. The third source would have a luminance of zero, because the wavelength is outside the visible spectrum.--Srleffler (talk) 23:54, 4 December 2007 (UTC)
replies: text:  You are right. And "multiplied" needn't be in quotes. It's an inner product. 155.212.242.34 (talk) 21:08, 6 December 2007 (UTC)
replies: text:  "multiplied" would only be correct for discrete wavelengths. The correct term here is "convoluted".84.180.126.52 (talk) 05:50, 6 September 2012 (UTC)
thread_title:  Luminance 

message: Hi:
Shouldn't someone add that W/sr/m3 is commonly called a "flick?"
Thanks
Donicecapade 17:22, 18 June 2007 (UTC)
thread_title:  spectral radiance & flicks 

message: It is unlikely that Irradiance page can be expanded beyond two paragraphs, so is the case with other radiometric quantities. I suggest we should merge article related radiometric quantities under one article such as Radiometric quantities with one sub-section for each quantities. This will also make it easy to create equations where notations are shared across several definitions. pruthvi (talk) 14:24, 8 March 2008 (UTC)
replies: text: SI units and quantitites of measure generally have their own articles. Short articles are not necessarily a problem. The template at the end of the article is intended to help standardize notation.--Srleffler (talk) 14:50, 8 March 2008 (UTC)
thread_title: Merger request: Radiometric quantities

message: I have proposed to merge Intensity (heat transfer) into this article, because the former explicitly states that radiance is an alternate name for the same thing, and indeed they appear to be the same physical quantity. Wikipedia articles are organized by topic, not by name. When one thing has two names, both are covered in a single article. This is related to the fact that Wikipedia is an encyclopedia, not a dictionary.--Srleffler (talk) 04:23, 21 October 2008 (UTC)
replies: text: Intensity and radiance are two different measurements, the difference being obvious because they have different units. blackcloak (talk) 03:52, 27 May 2009 (UTC)
replies: text: "Intensity" is not a well-defined quantity, once one leaves the confines of a single field of study. Its units depend on the context. From the article linked above, it appears that in the study of heat transfer "intensity" has the same units as radiance, and in fact is a synonym for radiance. --Srleffler (talk) 03:12, 28 May 2009 (UTC)
thread_title:  Merge in Intensity (heat transfer) 

message: The note accompanying Radiance in the table says "per unit projected source area" (my italics).  Granted there is a symmetry between the projecting and projected area, but when considering radiation emitted from an arbitrarily shaped surface into space, with no particular absorber in mind (e.g. the situation described by Planck's law), doesn't it make more sense to use area for the emitter (hence the projecting area) and solid angle dΩ for the divergence of the radiation leaving an infinitesimal area dA?  If radiometry is supposed to be neutral about the light field source and sink then "projected area" doesn't seem sufficiently neutral in that regard.  --Vaughan Pratt (talk) 10:09, 2 May 2012 (UTC)
replies: text: "Projected" refers to mathematical projection of the source area (or an element of area) onto the plane perpendicular to the receiver. You seem to be confusing this with the optical meaning of "projected".--Srleffler (talk) 17:05, 2 May 2012 (UTC)
replies: text: Ah, thanks for clarifying this.  Given that "projection" is far more commonly used with its optical than its mathematical meaning, should this clarification be made somehow in the article?  --Vaughan Pratt (talk) 17:30, 2 May 2012 (UTC)
thread_title:  Per unit project''ed'' source area? 

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thread_title:  External links modified (January 2018) 

message: An editor has asked for a discussion to address the redirect Orders of magnitude (radiance). Please participate in the redirect discussion if you wish to do so.  Utopes (talk / cont) 20:33, 8 April 2020 (UTC)
thread_title:  "Orders of magnitude (radiance)" listed at [[Wikipedia:Redirects for discussion|Redirects for discussion]] 

message: An editor has asked for a discussion to address the redirect Watt per steradian per square metre. Please participate in the redirect discussion if you wish to do so.  Utopes (talk / cont) 20:33, 8 April 2020 (UTC)
thread_title:  "Watt per steradian per square metre" listed at [[Wikipedia:Redirects for discussion|Redirects for discussion]] 

message: At Talk:Specific radiative intensity#Requested move 8 October 2022 I have proposed that we rename that article Spectral radiance and move content on that topic from this article to that one. "Specific radiative intensity" is a synonym for "spectral radiance", and Wikipedia is not a dictionary—we need one article per topic. Srleffler (talk) 22:54, 8 October 2022 (UTC)
thread_title:  Split off spectral radiance