Hummmmm… I’m not getting that result when I try it…
see this file…
Attachments
TextureScaleTest_004.blend (1.03 MB)
ok, I scale one of the cube, and I have bigger texture, so I must scale the texture one more time… In my blend I have three objects and six materials, and I tell you that bad approach 
Perhaps I’m missunderstanding … is it that you do not want the texture to change size when you scale your object? if so…
just use the same material (one material on all objects and set it to use ‘Object’ in the texture cordinates node… then check the little box at the bottom that says “From Dupli” and that should do it…
I was thinking you were wanting the textures to change size when you scaled the objects… my bad…
TextureScaleTest_005.blend (999 KB)
Hi. I have uploaded a new file with materials to blendswap. It contains a Blackbody reference for lights (Blackbody node will be new in Blender 2.69). And I have included a Lamp Material that I would like to share here:
The node setup is similar to the Glowing Material I posted:
I have used Camera Ray feature to reduce the strength emission coming from the lamp, so you can appreciate glossiness in the lamp.
Depending on the light of you scene you would need to tweak the strengths of the node setup.
NOTE: It works fine with white color lights, but depending on your monitor you can see the glossy reflections of the lamp or not. If you have an old monitor you won’t see them.
If you want to see the blackbody renders reference you can visit this article.
i did some testing myself
i tried to get an old look like in 1900 with filament lamp
and if you avhe any greyish white part in your scene all these mat will become strongly brownish
so not certain if this is realist !
by the way in which SVN did you find this new lamp node with many othe vars ?
happy cycles
Perhaps someone in this thread can help. I’m looking for a node tree that was posted a few weeks back. It was set up so that a low res texture could be used and not interpolated. I believe it was using math nodes on the UV coordinates to clamp the values mathematically, which is very close to something I am working on right now.
Does anyone recall seeing this?
edit: figured out the problem I was having now, but still would like to try and find that other example.
@RickyBlender, I have used the Blackbody node, wich appears in development versions: http://builder.blender.org/download/
The Lamp node is a node group. You can see the setup in the post. The black body node gives real colors than you can find in Nature. 1900 match with a candle. I think a tungsten filament should be 2500-2900. Fluorescent light from 6000 - 7500. There are a lot of references in google.
I have posted in blendswap a metal packwith 18 material setups, most of them explained here. If you want you can download the file there. Enjoy them!
i understand what you mean i did some search on the subject
but as i remember from experience with low wattage filament lamp
the colors for white or greyish object is not dark brownish
the color you show in your own test looks vey brownish
which i don’t think is representative and physicaly real or correct
have you ever seen such brownish color with filament lamp ?
see test here for a 25 watts lamps filament lamp
not certain if it is appropriate to use this node to change lamp source color?
as you can see the white greyish colors are totaly brownish
other are not too bad !
i dont’ remember when using 25 watts filament lamp
that white was becoming brownish in real world!
thanks
@jandress,… yup, that was what I was looking for. My solution ended up being exactly the same without even realizing it. I posted it in the blender tests forum, and another user has already suggested an optimization though.
Thanks for the demo, this appears to behave exactly as it does with film and tungsten lights in the analog parts of reality.
(Would be interesting to try to simulate non continuous spectrum lights i.e. unbalanced fluorescent that simulate white light with three spikes in the spectrum.)
@RickyBlender, your scene seems very interesting to test this. I think it depends on the strength. Normally I don’t use lamps, only meshlights, but imagine you have only a 25watt bulb inside a room. It will be dark. Normally you have 60w or 100w in a well-lit room. Apart from this, if you take a picture, with only that lighting, your image will be dark and probably yellowish. You will need to setup the “white color balance” to get accurate colors. By the way, “white color balance” in advanced digital cameras is measured in Kelvin degrees, like the black body.
Also you can take the light of a window. This light has different colors depending on the hour of the day. At sunset the light will be yellowish. At noon it will be more white.
Could you share your file to test some setups?
What you have to remember is that in film or photography, the appearance of an object is very much dictated by the setting of the camera (particularly white balance). Most cameras will try artificially shift the white point so that a white object in an image will actually look white when printed or displayed on a computer screen. In reality the object will have a colour cast based on the colour of the light source since it can only reflect colours of light that are incident upon it.
To a degree - this process also happens in your eye. A white object viewed under a filament lamp or a fluorescent lamp will still look white to you since your eyes (and brain) compensate for the colour cast.
Look how different this white cup looks based on the white balance setting of the camera. In the worst case - it does have a decidedly brown/orange tinge to it.
If you are going to white balance your images as you would in film or photography - what the actual colour temperature is is largely unimportant for single or similar light sources - just choose a temperature that looks aesthetically pleasing (this is afterall what you do setting your white balance on a camera).
The only time it should really be taken into account is if you have contrasting light sources and need to show the colour contrast between them (i.e. a scene lit by lamps of different colour temperatures like this one) - or you want to show something with some level of scientific accuracy (i.e. metal heating up, star colours etc)
is there some var to adjust the white balance in blender
mind you i’ll try to test a real filament lamp with transparent glass
and see what color it feels like!
now if you begin to play the temp it also changes the color
so it become harder to adjust it !
thanks
Yes - If you use the “RGB Curves” nodes in compositor - you can set the white (and black points) in the image. They even have eyedropper buttons so you can select a medium grey area in your image from which to balance.
Here are some screenshots:
This is a pure white sphere lit with a single point lamp which has a yellow cast on it (to simulate a typical filament lamp)
This is the same sphere after applying a white point correction via compositor.
Here is the node setup of the compositor (note for the white point - I clicked the colour box - then the eye dropper in the RGB colour pop up and sampled part of the sphere in the left node. Finally I adjusted the “brightness” of the sampled colour using the slider to the left of the RGB colour as the image was a little too bright).
if you look at your first pic i guess it is about right for a filament light
but if you look at my sample pic and the one given in thread here
it is a lot more brownish then that!
and i was more thingking about Cycles then using composite
i can always add an RGB curve and do samething in cycles
but still there is not direct way to get a realist equivalent for the different lamps sources
using this blacknode !
i wanted to emulate a scene from 1910 with some filament lamp
and using this blachnode it is not realist !
thanks
Yes - I was only approximating a filament lamp colour because I didn’t use the black body node as it only exists in experimental builds - and i’m using 2.68 official build. However the principle still applies - you either need to apply a white balance correction to the image to simulate film or the human eye - or you need to correct the lamp colour. You cant apply physically correct lighting without applying some sort of white balance - and expect it to look “correct”.
My images were rendered using cycles - and from a physical standpoint - the colours in the image you get is correct - from a white object you can only reflect to the camera wavelengths of light that are incident upon it.
Whether you actually perceive the reflected wavelengths as a true representation depends on how you are capturing the image. The human eye applies corrections to any image you perceive - so what you think is “realistic” is merely your eye (and brains) interpretation of the scene
What cycles doesn’t and can’t do is apply this type of automatic white balance correction - which is why you have to add it in manually.
I dont understand this statement. No digitally produced image is “realistic” as in what the human eye would see. Whether its a photograph or a rendered image - the final product is always an aesthetic approximation based on the limitations of the technology (i.e. colour space, dynamic range etc). All photography applies some sort form colour correction to make an image appear to look similar to what your eye would have perceived. Digital renders are no different. If you want to apply physically correct lighting parameters to your scene - you have to apply corrections that approximate the biological processes going on inside the human eye and brain which somewhat compensate for the colour cast caused by the spread of emission wavelengths of the light source.
You need to define “realistic”. Realistic in the scientific sense (i.e. what scientific instruments would detect as the principal colours in the scene?). Realistic from a photographic point of view (in which case you have to account for the dynamic range, grain, colour rendition of the film stock used or the bayer filter on the sensor, colour space and bit depth of the file and white balance parameters appliedl)…or do you mean realistic from the human visual perception point of view (in which case you need to account for the human eye’s and brains ability to compensate for colour cast, after image, dynamic range etc).
You have to remember that Blender doesn’t know about any of these things - so you either have to compensate for them when you setup your lighting (i.e. by adjusting the light colour output) - or compensate after the image has been rendered using compositing, photoshop or some other kind of image manipulation.
By your description - it sounds like you want to apply physically correct lighting - but not apply any type of correction to the image. If so - you’re not comparing like with like.
when you search web you have some tables of temperature blackbody equivalent for different type of lamps
and if you use these values you end up with exagerated colors
so i guess cycles cannot compensate for the eye-brain computer perception!
but again in real world of lamps there is the color IRC and intensity which can change the color perception
like i remember doing a lighting test comparing SHP and MH lamps
and even if you measure same lumens output the color rendering and light intensity to the human eye is totaly different
so i guess it’s very difficult to render as the eye perceive it with film or cycles renderer!
thanks
Ok - I downloaded build 2.68-r59254 to get the black body node.
I applied a colour temperature of 2500k to the lamp and rendered in cycles a sphere with a pure white diffuse material (i.e. RGB 255, 255, 255).
This is what I get straight out of the render
[ATTACH=CONFIG]254477[/ATTACH]
(which TBH looks about right when you consider the wavelengths of light emitted by a black body at 2500k http://www.lumicrest.com/images/color-temp-chart.jpg)
I then applied the RGB curves node to this render in compositor (keying off the brightish orange/brown area of the sphere) and get this:
Sphere looks white…
No it can’t (at least not yet). Even if it could - there is no guarantee it would be correct. Anyone familiar with white balance correction on a digital camera will tell you the automatic mode doesnt always get it right.
You have to compare Blender/cycles to a camera rather than the human eye. A camera can only compensate for color if you manually apply filters to the lens, or apply some software algorithm to the image which does this compensation “in camera”. Most digital cameras have such corrections built in - but if you try and take a picture with them turned off - you’ll likely get similar results to your renders under similar lighting. Since blender doesn’t have automatic color correction built in - you have to apply it manually, just as you would for a camera (and like you can do on most digital cameras if you take it out of full auto mode).
Exactly - hence the reason you have to compensate manually to make the image look correct according to what your perception.
You have to remember that even what you see with your own eyes is only your eye and brains interpretation of the real world. Subtleties in eye and brain structure/chemistry can lead to people perceiving the colours of an image very differently (e.g. colour blindness). Just because you perceive an image and its colours in a certain way - doesn’t mean everyone else will.
You have to approximate what you believe is correct. If the brown/orange tint caused by the colour temperature of an incandescent light reflecting off a white object doesn’t look correct to your eyes - apply a colour correction to make it look like what you feel is correct.
