Lighting the clouds from underneath

[AC5LT43R]

Hey, I want to create the effect of clouds being lit from underneath by ambient city lights, however the light source options seem fairly limited. So far I've tried a light source, but placing the light where I want the light to emit from makes it look like I've just set off a nuclear bomb. I've also tried to using the surface shader on the whole planet and turned luminosity on, which didn't work either. Is it possible to import and obj like a plane, and turn it in to a light?

[red_planet]

Quick experiment shows that you should be able to achieve your aims with a standard TG light source (Lighting tab, Add Light Source .. Light Source).. You will need to bump up the strength quite a lot.

Hope this helps

Chris

[AC5LT43R]

I have already tried this method but unfortunately the angle and height of the camera means that the light source is visible (thus the nuclear bomb effect) and I can't hide it behind geometry.

edit: I exported the lights as a clip file and imported them in to my scene, and now it gives me a much better result than the light I had, thanks!:)

[red_planet]

Have you tried turning off  "glow in atmosphere" ?

Rgds

Chris

[russe166]

Hi!
Is it this effect that you're looking for?

[bobbystahr]

You might try sinking a Light Source under the ground and turning it up quite high and making it's size cover the area of the sky where the city would be...I'm assuming we can't see the city ie: it's in the distance This has worked when I wanted light in a room but no shadows....kind of an ambient light. give this a try....EDIT...I turned off all light effects like cast shadows, glow, etc.,...everything but the light strength as you'll see in the .tgd.

[Oshyan]

Luminosity illuminating clouds is possible, but you may need fairly high GI settings to make it work well. You can apply a material and make it luminous for any object or terrain, but you may need very high values to get it to light up other nearby objects, or clouds.

- Oshyan

[Dune]

You might be able to fake it by giving the cloud a little illumination + using the shadow function of the cloud layer, masked by height control. Theory, just thinking aloud.

[bobbystahr]

I have already tried this method but unfortunately the angle and height of the camera means that the light source is visible (thus the nuclear bomb effect) and I can't hide it behind geometry.

edit: I exported the lights as a clip file and imported them in to my scene, and now it gives me a much better result than the light I had, thanks!:)

might we see a render of the result...curiously yours....

[bigben]

I tried this a while ago with the global city lights image from the blue marble set. Works OK using that image in a surface shader and pumping up the luminosity

[AC5LT43R]

I tried this a while ago with the global city lights image from the blue marble set. Works OK using that image in a surface shader and pumping up the luminosity

Sounds interesting, I'll give that a go Do you remember how high you put the luminosity? As I just applied a yellow coloured surface shader and still got no light in the clouds.

might we see a render of the result...curiously yours....

All in good time!

[Oshyan]

Luminosity of 1 should be fine, depending on the height of your clouds and position of your camera. From ground level with a single 100% coverage surface layer and a red color, luminosity of 1 gives quite red and fairly light low-level cumulus clouds even with the sun -2 degrees below the horizon. But this is with a 100% coverage surface. If you're using e.g. a lava effect that only covers a small percentage of the surface, you'll need much higher luminosity values.

- Oshyan

[bigben]

From the way, way back machine: http://www.planetside.co.uk/forums/index.php/topic,2686.msg27258.html#msg27258, Remembered the idea, but forgot the data source, USGS landcover data.

Couldn't resist another try with TG3. The yellow blur is Sacramento, sun is just below the horizon. Localised cloud over the city.
Luminostiy 100
GI 4 4
Atmosphere samples 64

...and then throw in some moonlight and a mid-level altocumulus layer..

[bigben]

... then take some craters from http://www.planetside.co.uk/forums/index.php/topic,18638.msg181315.html#msg181315, remove the displacement, colour adjust to make small white circles on black and add that to the surface mask for the "lights". 

0.1-0.5m circles masked by the modified USGS landcover image (reduce the saturation of the tint a bit and lowered luminosity to 70).  The atmosphere glow near the surface isn't too bad from a distance and this could make for some very interesting night scenes. Dropped the detail from 0.7 to 0.35 to speed up the render so the cloud detail is a little less in this one.  This is very promising for what is essentially a very simple setup.

[bobbystahr]

brilliant Ben