Light source appearing as a dark object, and not giving off light

Started by oggyb, January 07, 2007, 05:48:23 PM

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Any idea why a light source might behave this way?  The camera is inside a crater with various overhang-like shaders applied to it.

I include a screenshot and the file.



Your Source Radius is too big. Make it around 10 and you will see the light, or drastically increase the Strength to something like 10e+006. I don't know why, but the bigger the Source Radius, the less intense the light.


I would think that's because the light is being spread over a larger area - less intensity per area given the same luminance.

- Oshyan


I guess it makes sense if you put it like that.

Though common sense might dictate that a larger light source equals more light ;)

Oshyan, I know I've said quite a lot about TG2 already, and while often it's the problems that become the most vocal, let me also state that I absolutely love this product as it is already. And has a registered user (Deep), I already believe I have very good value for money even with the Tech Preview.

This is a wonderful program, and I any other hobby or spare time I had previously to the release of TG2 has all but evaporated as of late, simply because I have so much fun with it. My wife who is a matte painter has also expressed her admiration for the software, noting that it is a great resource for her to quickly generate photoreal elements easily.


njen, it's great to have this positive feedback, so thank you. We do also very much appreciate criticisms, suggestions and other comments of course. Your feedback certainly has not seemed overly negative, and in fact I have yet to see anyone here who I feel has focused overly on the undeniable problems of the Tech Preview.

There are a lot of issues and a lot of work to be done. Being aware of as many problems as possible is absolutely vital to us being able to produce a good, solid, polished final product. Your input and that of everyone else is greatly appreciated.

- Oshyan


Thanks for the help guys.  It was just way to dim!!

I thought that the brightness of a light source would follow the same design as for sunlight, but it seems to be about a thousandth of the brightness.  The radius makes no difference to the light cast, it only makes a difference to the size of the visible disc.

The radius causes the source to become dark if its boundaries will not fit inside an area of terrain. . . so, if it's used inside a cavern, my guess is that it has to physically fit inside to work.


If it's a spherical light source that essentially has a surface area, the light intensity will fall as the sphere gets larger, as the "photons" emitted are less concentrated from the source and scatter more at the start of their journey. If you double the light source's size then try doubling its strength. A usual consequence of area lights being increased in size is also that the 'samples' of the light need to be increased. Instead of imagining a tiny lightbulb, imagine a large luminous spherical light fitting that is made of frosted glass. If you want an intense lightbulb with hard shadows, make it very, very small.

At least that's my take on it and how I regard it in my main 3D app, but it would be nice to get that confirmed, and no doubt I will be shot down in flames  ;)

I'd like to second Njen's comments about how good TG2-TP is. I'll find out later if a sky I made is accepted in a shot for a production I'm working on.
Some bits and bobs
The Galileo Fallacy, 'Argumentum ad Galileus':
"They laughed at Galileo. They're laughing at me. Therefore I am the next Galileo."

Nope. Galileo was right for the simpler reason that he was right.


Jim, that's essentially my understanding as well.

The sun is currently handled as a distant point light source (which has its own issues that will be addressed). The sun "disc" effect is just a simple implementation that renders a colored disc over the sun's position, so it doesn't really behave like other light sources that have an actual radius. The control you have over the sun's size and effect on the scene will be improved in the future.

- Oshyan