what happens if there are multiple point light sources? does the light sum into greater intensity, or is there some formula it follows?
snowshoes7
This is an interesting question. I would believe that it would sum into greater intensity--however, the proportion of the sum made up by the light from each source would, I would guess, depend on the exact distance between the light and the surface in question /per light/. I.e., it would sum, but if one light is much closer to a surface than another, that close light would make up more of the light received on that surface. But, in this slide, since radiant intensity is defined as independent from distance--it probably couldn't sum in /that/ way specifically.
SuryaTalla22
I wonder why Candela was chosen to be units of Watts per steradian, and why this is one of the base SI units? This is interesting, since I always thought of the 7 base SI units as being the most fundamental, and it seems as though Candela is further downstream of these base units.
henrykhaung
To answer Surya's first question, since the candela is used to measure the visual intensity of light sources, it would make sense to use the units Watts per steradian. Watts to represent power and steradian to represent how much is seen from a point in terms of radians. This makes sense because intensity of light can be different from different angles as shown by the image in the slide.
lycorisradiatu
@misha-wu I believe when there are multiple light sources, the total intensity at a given point is the sum of the intensities of each individual light source. There are several factors that could impact the total intensity, including the distance from the point to the source and also the presence of any intervening obstacles.
AnikethPrasad
@misha-wu I found an answer here: https://people.eecs.berkeley.edu/~jfc/cs184f98/lec28/lec28.html#:~:text=In%20its%20simplest%20version%2C%20it,be%20finite%20to%20apply%20superposition.
It mentions that when there are two or more light sources, the total light intensity measured at any point in the environment is the sum of the intensities measured with just one of the sources on at a time.
Alescontrela
@misha-wu whether or not they sum up has to do with the direction of the rays. I believe if they travel in the same direction they would add up. Orthogonal rays would sum along their individual directions
GarciaEricS
@ Misha-Wu. We actually do something in 16A lab that involves a similar idea. We illuminate multiple pixels, and we assume the illumination we see is a linear combination of the illumination we would see from each individual pixel. This relationship begins to break down as the total illumination breaks down. So perhaps the relationship is linear until the illumination grows to large. This makes sense to me at least, since if we think about a lot of different light sources, I feel like it could only become so bright, even though we could add more and more sources.
weszhuang
Is it ever possible for two separate point light sources to end up as the sources which contribute rays of light along the exact same vector to some point receiver?
stang085
I think it's so interesting that cd is one of the standard measurements and it's not something that's widely taught in schools. I feel like it just tells how we don't really teach about light as much as we do for other sciences
what happens if there are multiple point light sources? does the light sum into greater intensity, or is there some formula it follows?
This is an interesting question. I would believe that it would sum into greater intensity--however, the proportion of the sum made up by the light from each source would, I would guess, depend on the exact distance between the light and the surface in question /per light/. I.e., it would sum, but if one light is much closer to a surface than another, that close light would make up more of the light received on that surface. But, in this slide, since radiant intensity is defined as independent from distance--it probably couldn't sum in /that/ way specifically.
I wonder why Candela was chosen to be units of Watts per steradian, and why this is one of the base SI units? This is interesting, since I always thought of the 7 base SI units as being the most fundamental, and it seems as though Candela is further downstream of these base units.
To answer Surya's first question, since the candela is used to measure the visual intensity of light sources, it would make sense to use the units Watts per steradian. Watts to represent power and steradian to represent how much is seen from a point in terms of radians. This makes sense because intensity of light can be different from different angles as shown by the image in the slide.
@misha-wu I believe when there are multiple light sources, the total intensity at a given point is the sum of the intensities of each individual light source. There are several factors that could impact the total intensity, including the distance from the point to the source and also the presence of any intervening obstacles.
@misha-wu I found an answer here: https://people.eecs.berkeley.edu/~jfc/cs184f98/lec28/lec28.html#:~:text=In%20its%20simplest%20version%2C%20it,be%20finite%20to%20apply%20superposition.
It mentions that when there are two or more light sources, the total light intensity measured at any point in the environment is the sum of the intensities measured with just one of the sources on at a time.
@misha-wu whether or not they sum up has to do with the direction of the rays. I believe if they travel in the same direction they would add up. Orthogonal rays would sum along their individual directions
@ Misha-Wu. We actually do something in 16A lab that involves a similar idea. We illuminate multiple pixels, and we assume the illumination we see is a linear combination of the illumination we would see from each individual pixel. This relationship begins to break down as the total illumination breaks down. So perhaps the relationship is linear until the illumination grows to large. This makes sense to me at least, since if we think about a lot of different light sources, I feel like it could only become so bright, even though we could add more and more sources.
Is it ever possible for two separate point light sources to end up as the sources which contribute rays of light along the exact same vector to some point receiver?
I think it's so interesting that cd is one of the standard measurements and it's not something that's widely taught in schools. I feel like it just tells how we don't really teach about light as much as we do for other sciences