PointLight lumen power
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Hi Frederik (and anyone else), please don't take this thread the wrong way. This is not about showing LightUp to be great / scoring points or whatever. I hope we can have adult technical discussion here.
I was just surprised - as I'm sure others would be - as to why when entering what I thought were reasonable values for f-stop and shutter speed - as in the kind I would use with a real camera - I get such a dark image.
And yes, I realized the Maxwell sphere was making the surface a little (but only a little) closer to the box surfaces.
I'm looking to be educated here. I haven't built a real 2m box and placed a 75 Watt bulb in there - but finger-in-the-air, I would expect it to be quite bright in there.. No? So I was expecting the renderers with physical camera controls to give a result of a brightly lit box.
I see I am mistaken because they're very dark. But why? Can you explain?
Adam
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what are your camera settings for vray? The default setting in vray is for a sunlit exterior scene. A light bulb in a box is very dim compared to sunlight, and the camera exposure will reflect that.
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@andybot said:
what are your camera settings for vray? The default setting in vray is for a sunlit exterior scene. A light bulb in a box is very dim compared to sunlight, and the camera exposure will reflect that.
Yes, making the shutter speed 1/4th second brightens it up a lot (and for Thea too), so it looks like thats the problem: the ISO and/or shutter speed multipliers need to be larger.
I guess I'm surprised it would take a quarter second exposure to capture a light bulb.. live and learn.
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Glad you figured it out!
I'm sure you realize there's the third variable - aperture. You're probably at f8, change to smthing like 3, and at iso 400, that shutter speed could probably be 1/60. However, aperture only matters when using DOF, and shutter speed matters for motion blur, otherwise, pick any combination, and you'll get the same EV. That's one thing that's really slick with Maxwell - they have the EV slider which takes the guesswork out of these photographic concepts. -
@adamb said:
I guess I'm surprised it would take a quarter second exposure to capture a light bulb.. live and learn.
Serious... Are you really surprised...???
I recall - in particular from back when we had real film in cameras - that to take a picture inside at night, would require a flash light where the shutter speed needed to be set at 0.3 sec...
If you didn't have a flash light (or didn't want it because of the artificial light appearance), you could:
A.) Use a film with high ISO (I recall up to ISO 2000), but then the penalty would be that the image produced would be very grainy...
(The higher ISO, the more grainy-ness)B.) Increase the exposure time... (Resulting in funny looking images, because motions would be evident)
C.) A combination of A and B
D.) Wait until it became daylight...
Please read the article Patrick posted yesterday...
I know the link seemed broken yesterday, but it works today and contain some wise words about photography, exposure time (shutter speed) etc... -
Really, the thread creator should have researched a little before making such uninformed comments. Did he even try to take a photo at a totally closed room at night, a single 75 watts lightbulb, ISO 100, shutter speed at 1/60 and F8?
Really, he should have before "guessing" that it should be bright.
"Surely a 75 Watt bulb in a small box photographed with a real camera loaded with ISO 100 is going to be brightly lit."No, it won´t.
Just made tests with my camera. A bedroom in my apartment with 2.8 x 3.3 meters. Two 75 watts lightbulbs. Room totally closed.
At the settings above, that the thread creator "thought" it should be bright, and therefore VRAY and Thea sucked... well, checkout below.
F8, ISO 100
shutter at 1/60shutter at 1/30
shutter at 1/4
F4, ISO 100
shutter at 1/60shutter at 1/30
shutter at 1/4
camera used: Canon SX130
ps: sorry for the hanging lamps. That´s the bottom of the ceiling fan. It happens the ceiling fan malfunctioned, so I opened it to see if there was any burned equipment, and somehow I lost the screws
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Nobody said anything sucked. It simply a question on a forum.
re: your bedroom experiment. Remember its a 1/r^2 falloff so 3m from a source will be 1/9th the power.
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The source is in the middle of the bedroom. Thus it´s 1,5 meters from the source. So it won´t be 1/9th of the power. Furthermore, there are two 75w lamps, so double the power. Furthermore, the lightball you used to illuminate your scene was larger than my lamps, and closer to the walls. Stop fighting with reality. People asked you again and again to give your shutter and aperture settings and you did not. You would answer just saying you expected any place being lit with a 75w lamp and by using ISO 100 to be brightly lit. I proved that was not true and you still won´t accept?
The truth: Thea and Maxwell are physically correct in your experiments above.
Here, a test a model of my room... same space... same settings as the first photo
you accused Thea and Maxwell of illuminating too little compared with real life. In my test, it shows they actually illuminated too much.
Of course, a REAL REAL test would depend on several other things, like really MODELLING the lamps and getting the real values of emmitance per watt, etc, etc, from the lamp manufacturer. It´s a compact fluorescent lamp, 15W, but the manufacturers and salesman say they are illuminate the same as a 75W incandescent lightbulb.
Having watts alone is not enough, we need watts AND efficacy, and probably also temperature color in kelvin.
but one thing is certain from the tests... even not modelling the real lamps, Thea and Maxwell results are much closer to real life results.
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Not sure if you're just trolling.. however, nobody is "accusing" anyone of anything. I was simply surprised to get the results I got.
As to aperture and film speed, these are simply emulated controls to make a raytracer feel familiar to those with knowledge of photography.
LightUp doesn't aspire or wish to be an emulation of a physical camera. It provides a simple to use, fast lighting solution that allows users to navigate their models in realtime with reflections. The reason companies such as Pixar use LightUp is not to replace their Renderman rendering engines. Its because they can quickly play with lighting ideas and share those results with the teams. Ditto many others.
The reason many architects, set design and conference designers use LightUp, is because they can quickly get a good result to share with clients and move around at 30Hz to explore the space.
I'm very glad you are happy with still images from Thea and Maxwell. Carry on.
Adam
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Adam you are coming across a real pleb.
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Sorry, why am I a Plebian for asking a question? And what the heck has being a common man got to do with it!
I simply asked a question on a forum. I understand you think it was some kind of cunning attack - but it really wasn't - just my not understanding the settings of other rendering software.
If it really is the case, you cannot ask question on this forum without getting an earful of vitriol, then what is the point of the forum?
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@adamb said:
Sorry, why am I a Plebian for asking a question? And what the heck has being a common man got to do with it!
I simply asked a question on a forum. I understand you think it was some kind of cunning attack - but it really wasn't - just my not understanding the settings of other rendering software.
If it really is the case, you cannot ask question on this forum without getting an earful of vitriol, then what is the point of the forum?
Adam,
Asking a question is never a problem really, although, with as many users on the forum as there are, an occasional grump can pop up. However, being impartial, as I have no experience with any of these renderers, you have seemed unwilling to receive the answers provided. It seems that you are resistant to "seeing" that ISO, aperture, and f stop settings are all integral in capturing the light in any given scene.
The example that AcesHigh provided was a thoughtful and reasonable demonstration of the answers provided to your query. I'll bet that his natural eye perceived the lighting in the room exactly the same, but his camera captured the scene differently (based on different settings) Consider that no matter how well lit a room or box is, a blind person will never see the scene. In other words, the physics of the light source is independent of the instrument capturing the light.
Now please take to heart this is not an attack on you or your question, but it does come off as disingenuous when as a lighting program developer you will not accept basic photographic principles being an integral part of another developers lighting program. These principles are used to emulate the way cameras actually work in some of the rendering packages you have studied. It neither makes them inherently inferior or superior to LightUp. Simply put, LightUp uses a different instrument/method to capture the light in a scene. This IMHO really is a matter of apples and tomatoes as Frederick posted somewhere above.
When you asked what settings you might have missed when you got your results, you got answers.
Lastly, condescension and name calling are out of bounds
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@adamb said:
Sorry, why am I a Plebian for asking a question? And what the heck has being a common man got to do with it!
@adamb said:
I'm very glad you are happy with still images from Thea and Maxwell. Carry on.
Because you are acting like one! You should be intelligent enough to rise above posting such comparisons where they have no value. The renders are not direct comparisons, the camera settings are not the same or true to real-world parameters. You have not read the manual.
The default Thea camera works well for brightly lit exteriors, not a light in a box. You are still arguing about the accuracy of Thea, Vray etc when one could argue exactly the same points against LightUp.
I can just as easily make a fantastic Thea render and then compare it to an inferior LightUp version, just because I didn't read the LightUp manual. It's not to say one is better than the other; they are just different. The thread became sour the moment you tried to show up competitors who have tried-and-tested amazing results.
Imagine BMW, for example, setting a fast Nurburgring lap time. The same BMW test driver then takes an Audi round the track at half pace. The BMW will always win but they were never driven the same thus making the results unfair.
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You don't appear to understand the meaning of the word 'pleb'. Whatever.
@olishea said:
I can just as easily make a fantastic Thea render and then compare it to an inferior LightUp version, just because I didn't read the LightUp manual. It's not to say one is better than the other; they are just different.
On that we agree.
@olishea said:
The thread became sour the moment you tried to show up competitors who have tried-and-tested amazing results.
Right from the start, I said it was likely me misunderstanding setup of these other renderers. And indeed it turned out to be just that and no "showing up" of anything. The fact that you feel the need to wade-in with name calling I think speaks volumes.
Post what reply you will. I'm done with this thread.
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Please not another "Plebgate"! I know exactly what it means Adam and it was the way you were coming across, not to say you are indeed a pleb. You should be informed enough to know about camera settings, putting you above any common or beginner 3D renderer users.
I have no problems with you or your software whatsoever, but to post things like this in a public forum is deemed a desperate attempt to discredit other software. Of course you keep telling us it's not like that, but nobody believes you. I have never seen anyone from Thea, Vray, Twilight, Podium, nobody posting images comparing their software to others; in fact it's considered highly unprofessional. It may happen from time to time with the users of such software, but not the software developers themselves. Correct me if I'm wrong but I just don't see this happening anywhere else.
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@adamb said:
I was simply surprised to get the results I got.
It´s hard to believe someone who develops a rendering software has no knowledge of real results from a camera at those apertures and shutter speeds.
Also, even if you were surprised, you could have worded your responses to people telling you about aperture and shutter speeds, as if you were learning. But no. Your responses to people telling you about that was more on the line of DOUBTING what they were telling you. Even after I posted the results of a real camera, you DOUBTED the results, saying it was a bigger room and that was the reason it was darker. Like if it was a 2x2 room it would be much brighter, and completely forgetting my test used TWO lamps.
So for someone simply "asking a question", you doubted a lot people's answers to you.
@unknownuser said:
LightUp doesn't aspire or wish to be an emulation of a physical camera. It provides a simple to use, fast lighting solution that allows users to navigate their models in realtime with reflections. The reason companies such as Pixar use LightUp is not to replace their Renderman rendering engines. Its because they can quickly play with lighting ideas and share those results with the teams. Ditto many others.
The reason many architects, set design and conference designers use LightUp, is because they can quickly get a good result to share with clients and move around at 30Hz to explore the space.
ok, after all this advertising, I should tell you to check Thea's new render layer in Sketchup, but forget it. That´s not the question. The fact is that you started the topic by suggesting Thea, Maxwell and VRAY apparently did not got realistic results for a 1200 lumens lamp with ISO 100. And that LightUp seemed to be better in that regard.
Then, as we proved to you that those other renders get it more right than LightUp, your tone in the thread has changed to "LightUp doesnt aim to get realistic results, our aim is to provide fast lightning and feedback".
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Iv had great fun readin this one. Don't know how i ended up here, but im searching for what render software to go for so thats the reason.
From an pleb as me comming in and reading this its very funny. Cause from what i can read here and from what i found elsewhere in my search is that there is so many prefrences to set to get it right. Some have prefrences that others don't. And that can be both good and bad in my opinion. Thats why all programs have defaults.
And what is the default? well that can be a lot. And from my point of view here. And this post made me think. Cause many renders look at it with a camera point of view. The idea of you taking a picture of something "real". While lightup in my mind looks at it with a human point of view. Humans don't have the same shutter speed as a camera, so we have a hard time capturing what a camera can do. Both are kind of wrong and right, right? You can't compare a human to a camera I think this is more of a argue about default and standard. Thea which i think i will go for btw has a setting as a camera, but it should be easy after this thread to set the "camera" to act like i as a human see the world, thus showing of lighting in scenes to client as they will in real life.
Like my profile picture. it capture a moment of me driving, but its just impossible to redo that picture standing still. i would just fall to the ground.
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