Render from Terragen 3 Pro

[icarus51]

Hi friends,

I've played with Terragen 3 Pro a little. I've rendered a Cloudy Sky with Spotlight towards the clouds.
Data is:

Detail - 0.645
AA - 5
Atmosphere quality - 41
Defer atmo/cloud - On
Ray Trace Objects - On
Image Size - 780x450 pix.
Light Beam, Aperture width - 0.0829
                  Shape - 0

After about an hour of rendering time i get this outcome.



Question: why at this detail and other parameters of good resolution the light beam is so grainy? Have i to increase Detail, Atmo Quality or what?
Thanks.

[dandelO]

I just posted a workaround solution to this somewhere else when a friend asked the same question.
I realised a couple/few years ago that you can use a cloud, instead of atmosphere haze, the TG lightsources and atmosphere nodes have never played well with each other so I tried to find a way around it. I would have thought it could have been properly fixed by now but maybe it's a bigger job than we imagine. It is a pretty major problem, though, in my book.

See the difference in this image, atmo(32 samples) and lightsource on the left.
Cloud(9 samples) and lightsource on the right.

A real pain when you consider how important both atmosphere and light nodes are in 3D rendering, but it works, at least.

[dandelO]

I should probably clarify this, I realised I didn't explain it properly here...

You said you're pointing the light into the clouds and your image shows that there's no noise in the cloud from the lightsource.
What you should do is disable the haze in the atmosphere node(set to 0), and replace that haze with a cloud layer that reaches the ground. In my quick example I just set the cloud height to the same height as the light(5m) and made sure it was deep enough to just pass the ground at its base(12m). You'll probably want to make it much deeper to simulate a good haze, if so then you'll also be able to lower the density so that the samples stay low, a thicker layer doesn't need to be as dense. The most important part is to make the layer depth just more than twice the height so it reaches the ground. If there are low gullies, or negative offset of the planet surface that goes lower than Y=0 then just adjust the height of the layer to fit.

[jo]

Hi,

We're aware of this problem, it's the reason "Glow in atmosphere" is off by default for spotlights and light sources in TG3. For a spotlight beam to show up properly there needs to be something for the light to interact with. In the real world that would be dust or water particles etc. in the air. To get the beam to show up nicely in TG you need to have a thicker atmosphere to give something for the beam to interact with, basically along the lines of what dandelO is suggesting. I'm not sure you need to disable haze in the atmosphere, but you can experiment to find the effect you like.

Other applications fake this by having "light fog" or similar. TG is in a slightly different situation because it's all about simulating real environments, and having a section of thicker atmosphere just for a light beam to show up goes against that a bit. Nevertheless we are considering adding light fog to make it easy to get spotlight beams because we understand this is an effect people want to get with spotlights.

Regards,

Jo