Hi,
first of all, thanks for your hard work. I am very enthusiastic of this restart of lux. Below I report a bug regarding the IES.
I have found an issue in IES emission intensity. I put two spot light source in a room, and I tested with luxrender classic and with luxcore alpha4 in blender. the left spot light is made by a material emitter and a glass lens to concentrate the light (very hard to compute). The right spot light is doing by a point light with applied an IES file from ERCO. The intensity of both light is the same, but the IES light seam that are about 15 time less intense. For this I test the ies light in luxclassic to check if there is the same issue, but seem that in lux classic the result is correct. please take a look on image below.
Thanks
nocivo
issue on ies light intensity
Forum rules
Please upload a testscene that allows developers to reproduce the problem, and attach some images.
Please upload a testscene that allows developers to reproduce the problem, and attach some images.
Re: issue on ies light intensity
It looks like a bug, can you post the test scene to reproduce the problem ?nocivo wrote: ↑Tue Feb 13, 2018 12:38 pm first of all, thanks for your hard work. I am very enthusiastic of this restart of lux. Below I report a bug regarding the IES.
I have found an issue in IES emission intensity. I put two spot light source in a room, and I tested with luxrender classic and with luxcore alpha4 in blender. the left spot light is made by a material emitter and a glass lens to concentrate the light (very hard to compute). The right spot light is doing by a point light with applied an IES file from ERCO. The intensity of both light is the same, but the IES light seam that are about 15 time less intense. For this I test the ies light in luxclassic to check if there is the same issue, but seem that in lux classic the result is correct. please take a look on image below.
Re: issue on ies light intensity
hi,
below the blender scene and the IES file.
the scene attached has the ies light gain set to 14. to recreate the bug, please down to 1. in this way you have the same intensity of the left light.
thanks
below the blender scene and the IES file.
the scene attached has the ies light gain set to 14. to recreate the bug, please down to 1. in this way you have the same intensity of the left light.
thanks
- Attachments
-
- spot-lens.zip
- (259.97 KiB) Downloaded 229 times
Re: issue on ies light intensity
Thanks, going to look into the problem.
Re: issue on ies light intensity
I should have fixed the problem: https://github.com/LuxCoreRender/LuxCor ... 48fcda8ce1
There was a missing "x 4 x PI" (12.56) factor that is pretty near to the "x 14" you had to use to much the outputs.
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Re: issue on ies light intensity
Hi,
Thank you for fixing the IES bug.
How does lux interpret the light distributions that are stored in that file?
Do you read the luminous flux from file or do you compute a relative value?
Are there any angular limits for IES interpretation?
To explain my application... I'd like to visualize car's headlamp beam patterns. They are usually very unsymmetrical. In some cases a resolution of 0.02 x 0.02 degrees is used describe bright/dark cut off lines.
Therefore the description locally very limited. Only +- 40deg horizontal and +10deg and -30deg vertical area.
In classic lux I had some troubles, but it was working issuing less detailed data.
Other renderers promise full IES support but they fail on that task quite often.
@B.Y.O.B.
Do you see any chance to integrate a low poly preview of IES lighting cone in Blender? Especially for unsymmetrical distributions it may simplify orientation a lot.
BR
Thank you for fixing the IES bug.
How does lux interpret the light distributions that are stored in that file?
Do you read the luminous flux from file or do you compute a relative value?
Are there any angular limits for IES interpretation?
To explain my application... I'd like to visualize car's headlamp beam patterns. They are usually very unsymmetrical. In some cases a resolution of 0.02 x 0.02 degrees is used describe bright/dark cut off lines.
Therefore the description locally very limited. Only +- 40deg horizontal and +10deg and -30deg vertical area.
In classic lux I had some troubles, but it was working issuing less detailed data.
Other renderers promise full IES support but they fail on that task quite often.
@B.Y.O.B.
Do you see any chance to integrate a low poly preview of IES lighting cone in Blender? Especially for unsymmetrical distributions it may simplify orientation a lot.
BR
OS - Windows 7 X64
CPU - Intel CORE i7
GPU1 - Variants of notebook card from nVidia
GPU2 - Variants of notebook onboard card from Intel
Lux - Latest possible relaease
CPU - Intel CORE i7
GPU1 - Variants of notebook card from nVidia
GPU2 - Variants of notebook onboard card from Intel
Lux - Latest possible relaease
Re: issue on ies light intensity
You mean in the OpenGL viewport?lighting_freak wrote: ↑Wed Feb 14, 2018 6:57 pm @B.Y.O.B.
Do you see any chance to integrate a low poly preview of IES lighting cone in Blender? Especially for unsymmetrical distributions it may simplify orientation a lot.
It could be done with an operator: https://blender.stackexchange.com/a/61712/29401
However it sounds like a bit of work.
The viewport render should provide you with a much more accurate preview of the light distribution.
I do not consider this high priority for these reasons. You can open an issue for it on github and I can flag it as "good first issue", maybe in the future someone with Python knowledge decides to implement it.
Re: issue on ies light intensity
Old Lux and LuxCore are baking the IES goniometric profile with a "width x height" array of values (a baked map of the IES profile). The default values is 512 x 256 and it is probably too low for your application. I don't think it was possible to change the resolution in the old Lux but it is in LuxCore. Not sure if the parameters are exposed in BlendLuxCore but, in the worst case, you can save the scene in text format and edit the scene to change the resolution.lighting_freak wrote: ↑Wed Feb 14, 2018 6:57 pm How does lux interpret the light distributions that are stored in that file?
Do you read the luminous flux from file or do you compute a relative value?
Are there any angular limits for IES interpretation?
To explain my application... I'd like to visualize car's headlamp beam patterns. They are usually very unsymmetrical. In some cases a resolution of 0.02 x 0.02 degrees is used describe bright/dark cut off lines.
Therefore the description locally very limited. Only +- 40deg horizontal and +10deg and -30deg vertical area.
In classic lux I had some troubles, but it was working issuing less detailed data.
Other renderers promise full IES support but they fail on that task quite often.
You probably need a far higher resolution than 512 x 256 to capture fine/small details.
There shouldn't be any other problem in your case but it is hard to say without doing some testing.
Re: issue on ies light intensity
They were not, they are now (next alpha release).