Each light apparently is equivalent to 110W (950 lumens). I have 2 tracks of these lights running along a ceiling, and there are about 30 lights in this particular space. A number of these lights are around 2m from the nearest wall and are pointed at the wall.
I find that I barely get any illumination from the lights without whacking up the default lumens output massively (5 or 10x the default 950).
The camera is a vrayphysical camera, f:4, 1/50th second at ISO:100.
Is this odd, or expected? To my mind, shining a 100W (or 50W) bulb at a wall 2m away would at least create a spot of light on that wall, even in a reasonably well lit space.
yes, I remember reading some threads some time back the the multiplier had to be bumped up in some instances I have to do it myself. I find it odd as well.
I find this odd, too! I get lighting data from our lighting engineers, but it almost doesn’t mean anything because the real world data that they give you doesn’t work. When I get these files I have to crank things up so much that I am really just guessing so the science is lost.
I am having problems with VRay IES and 3ds max photometric lights too. I work in LWF and with regards to camera settings everything seems to be working as the realworld counterpart. All my camera settings, both for exteriors and interiors, matches pretty much the setting I find when using my DSLR. But when it comes to IES lights I have to use some extreme luminance values, which makes it impossible to know what light you need to use in real life to get a specific effect. (Its also bad seen from a Global Warming point-of-view, hmm). Is there a connection between the system unit scale and how the IES light data is interpreted? It would be nice with a comment from Vlado on this subject.
I’ve found this to be true as well. And to answer you Vlado, they do work fine with mr. Even more weird is I’ve found that IES lights have very odd shadows from Vray, very crispy and no softening much of the time. I always figured I was just doing something wrong but the more I’ve experimented the more I feel that something is off.
I did have a thought about it though, in maya using a point light with IES data reveals 3 different methods for handling the profile. (The names escape me at the moment) I’m thinking that there are different light models for IES files as evidenced by the 3 options in maya for interpreting them. Maybe this is part of the problem, but I am totally guessing.
Ok; if you have a scene that renders differently in V-Ray and mr, can you send it to me at vlado@chaosgroup.com? We’ve gone through hundreds of IES files and they render consistently, but there might be something else in your scene.
There are indeed three different types of IES files, but there is no need to specify them explicitly - the type is written in the file itself (3ds Max does not allow you to change the type either).
I did a test last week with a scene I am currently working on. I did a render with both mr and vray - and they appeared to be nearly identical. But the strange thing is that while they looked right in a “night” setting, the light disappeared in the daytime version. I tried some different upscaling of the lumen settings and in this case a multiplier somewhere between 8 and 16 seemed to be what looked realistic. It is a little late now (after midnight), but I will try to post some of the renderings tomorrow.
To Deflaminis: did you check “use light shape” to get soft shadows. If you don’t you will get sharp shadows.
To Vlado: thank you for the response, I am sorry that I didn’t react on your answer until now.
Here are some of the test renderings I made, as mentioned above. Please read my post for details. Some additional information though: I am working in linear workflow, system units are cm and the camera settings are similar to real wold settings. EV means exposure value, so EV 5 equals a camera setting of for instance 1 sec. f5.6 ISO 100. Image 1 should represent a situation with no additional light sources, except for some exterior moonlight. Image 2 has the same light setting as image 1, but with the moon replaced with a sun. Image 3 and 4, with the power multiplied with 8 and 16 respectively, are the settings which are closest to how the lamps (Flos Glo-Ball) behave as I recall from my memory. A multiplier of 10-12 might actually be the closest.
The exposure is being changed from .5 to 1/128 second. It’s expected for the lights to become much dimmer, isn’t it? That’s a much faster shutter speed. Set your lights to 256 multiplier and they should look the same. That’s 8 f-stops worth if I’m not mistaken.
To davision: My point is not to have the light looking as bright in the day scene as in the night scene, as I am aware that the longer you expose the brighter the image will be - and vice versa. My point is to have the light behave/look real, whatever exposure settings I use. In this case I expected the light to be looking much dimmer in daylight, but not to disappear almost totally. The lamps are placed in a dimly lit corner, and my real world experience tells my that you will be able to see some direct light on the wall and table, and also in the reflections on the table surface.
To samuel_bubat: My materials are pretty correct, the wall have a reflectance of 80%, the floor 65% and the furniture (light oak) an average of 57%.
I have provided a couple of real photographs from RH Architects below as a reference. The left image shows the Glo-Ball lamp I used in my test renderings. The right image shows that even though there are a lot of light coming both through the windows and from the recessed light in the ceiling, the light from the table lamps are still pretty easy to spot on the surface of the table in the front.
Keep in mind that professional photographers use a lot of tricks to get a good image. What you’re looking for in terms of reality in your digital images, is not what you see through your eyes in real life.
Also, the one real photo on the right only shows sky light coming in through the windows, unlike your rendering which has direct sunlight. To me, the problem looks like your glo-balls are too dim in the night time render. They should be brighter and your exposure should be shorter.
Sorry to butt in, but I’m pretty certain psa is referring to the light cast on the objects around the lamps, not the direct look of the lamp surface itself. I agree completely with him, you can see the additive amount of light is wrong when he turns on the sun, as there is hardly any visible warm light even though the inside of the shelf is lit by low indirect sky and gi. Personally I would expect the peachy light from the “glowball” to add on top of the indirect light there.
