Lux measurement using Irradiance feature
Posted: Fri Dec 21, 2018 12:49 pm
Hi,
I'm a new user of LuxCore and first of all I would like to thank you for open source LuxCoreRender - it's really a powerful tool. I am also new to the physics of light so please bear with me and correct me if i misinterpreted anything.
My goal is to obtain a numerical representation of illuminance on a given surface, measured in "lux" unit.
I found there is a "Irradiance feature" available in LuxCore (it has also a python API in Blender available) and I have questions related to it.
1. I found a radiological definition of "Irradiance" which is quantified in watts/m². Does your implementation also measure it in this unit? Which C++ files should I look to find more details about the implementation of Irradiance feature?
2. Since I want the result in "lux" unit (which is defined in photometry as Illuminance (lumen/m^2)) , I would like to ask you if it´s possible to obtain lux values in some way from Irradiance feature?
3. I was googling about the conversion from irradiance (radiological quantity) to illuminance (photometric quantity), but reading this https://www.researchgate.net/post/How_t ... m_2_to_lux i am not sure if a direct conversion exists?
4. Why is the constant 179 used as the default scale value in Irradiance feature? Does it have to to anything with the conversion from question 3?
5. In Blender there is only a possibility to draw contour representation using this feature. Since my goal is to get lux value for each "pixel" on the surface, I need a way to export values. I was looking at the examples: viewtopic.php?t=374 and I found that .exr format is used to export the values. First of all I would like to ask you what do the exported values in .exr format mean (coordinate by coordinate)?
6. Is there a way of getting .exr file using Irradiance feature in Blender (previous example is an example using C++ engine directly).
Thank you for your time answering my questions!
I'm a new user of LuxCore and first of all I would like to thank you for open source LuxCoreRender - it's really a powerful tool. I am also new to the physics of light so please bear with me and correct me if i misinterpreted anything.
My goal is to obtain a numerical representation of illuminance on a given surface, measured in "lux" unit.
I found there is a "Irradiance feature" available in LuxCore (it has also a python API in Blender available) and I have questions related to it.
1. I found a radiological definition of "Irradiance" which is quantified in watts/m². Does your implementation also measure it in this unit? Which C++ files should I look to find more details about the implementation of Irradiance feature?
2. Since I want the result in "lux" unit (which is defined in photometry as Illuminance (lumen/m^2)) , I would like to ask you if it´s possible to obtain lux values in some way from Irradiance feature?
3. I was googling about the conversion from irradiance (radiological quantity) to illuminance (photometric quantity), but reading this https://www.researchgate.net/post/How_t ... m_2_to_lux i am not sure if a direct conversion exists?
4. Why is the constant 179 used as the default scale value in Irradiance feature? Does it have to to anything with the conversion from question 3?
5. In Blender there is only a possibility to draw contour representation using this feature. Since my goal is to get lux value for each "pixel" on the surface, I need a way to export values. I was looking at the examples: viewtopic.php?t=374 and I found that .exr format is used to export the values. First of all I would like to ask you what do the exported values in .exr format mean (coordinate by coordinate)?
6. Is there a way of getting .exr file using Irradiance feature in Blender (previous example is an example using C++ engine directly).
Thank you for your time answering my questions!