image quality with light rays

Started by Arkanias4, January 29, 2007, 12:19:29 pm

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Hi all! first thanks everyone for sharing files and tips. Wanted to have your opinion on this one. I know scale is not OK as it's just an exercise I started with twist and shear shader and that finished in playing with clouds and dramatic lighting. I find the image too grainy to my taste. Any idea to improve it within the TP.


Here is the tgd file if anyone is interested  :)


crank up your atmo setting quality samples to 64


Thanks Jay, I did raise number of samples for the cloud layer and forgot to do it for the atmo...


Without the graininess this looks good.  Nice job. - A great Terragen resource with models, contests, galleries, and forums.


Hi all !

I have similar problems with my light rays... when I increase haze density to achieve those rays the render becomes very grainy.
Quality settings just seem to have little effect on it.

I used following settings for my last render:

512x384 res, Detail 0.8(!), 4 AA, GI 4-4 , Atmosphere Quality - 50 Samples(which is quite a high value)
(see attached image)

I'am now trying same settings with 64 Samples for the atmospheric quality (as considered by buzzzz in this thread) and hope this will eliminate the grainyness...   if so, I just wonder why 14 samples more make such a big difference... but we'll see
rendering is in progress^^



Cranking up atmo samples to 64 will probably increase the rendertime a lot. I suggest you then lower GI settings to about 2-2/1-1. Or even use the fill light setup, which can be found here:


August 01, 2007, 07:13:34 am #7 Last Edit: August 01, 2007, 08:20:32 am by Ironshirt
I already tried different GI settings, from 1-1 up to 4-4...  with no success.

Currently I'am rendering with 64 atmosphere samples (at 50% now - and rendering for 1 hour) but if it fails I'll try
the fill light setup, thats an good idea...     


August 01, 2007, 08:27:05 am #8 Last Edit: August 01, 2007, 08:30:46 am by Tangled-Universe
The suggested GI-settings were only meant to save rendertime, since increasing atmosamples willl greatly increase rendertime, not to achieve better results. As far as I know and what I have seen myself, high GI settings rarely give better results in the atmo, so rendering at GI 1-1 should be sufficient and quite faster than rendering with GI at 4-4. Disabling GI and using the fill light setup will give "similar" results and will even save more rendertime.


to get those rays (without grain) i push the atmo samples to 80 - 100 or even higher, same with the cloud samples
GI to 1/1 max 2/2, quality render max 0.8.
The render time grows up, but .... if you want rays without grain ....  :-\


I would consider 64 atmosphere samples to be about an average for achieving low noise results with some rays in the scene. For heavily shadowed scenes with lots of rays you may need 128 samples or even higher. That's just what is necessary at this point to achieve high quality results in these specific circumstances. Fortunately in most other situations such high sample levels are rarely necessary.

- Oshyan


Thanks for all your answers! Really nice!

Increasing atmosphere number of samples did it...
I made two additional renders - the first with 64 samples and the second with 128. (attached, for those who are interested)
Detail was 0.7 here for saving rendertime.
A third one follows with the fill lightning setup and 128 atmo samples - I've to say that this setup needs most time for rendering by now.
The one with same settings but normal lightning took 3,5 hours - this one here is now at 4 and hasn't finished half of the second (final) rendering step. But I'am curious about how it will look   :o


With fill lights takes longer???
Strange...maybe GI is more suitable for rays, but honestly I have no clue.
"Normally" using only fill lights saves quite some rendertime. Sure you disabled GI?
Going from 64 to 128 samples is a great improvement! It seems you would even have to render it at 256 samples  :o amazing  :P
Nice work!


The 128 sampled picture definitely looks very nice.  Even with the little grain, it looks like a photo.
So this is Disney World.  Can we live here?


August 23, 2007, 08:02:50 am #14 Last Edit: August 24, 2007, 02:59:49 am by Ironshirt
Hi again!

First, thanks for your compliments!
I'm very sorry, but I couldn't post the promised image by now. I have a new job  and live here in Aachen for work (since three weeks now).
My 'real' home (including my tg2 license) is nearby the Nürburgring .  I go there every weekend and will be able to post the latest version of the image  from there( which is 1024*768 0.7 and 256 atmosphere samples). Sorry again for the long delay !

@ Tangled-Universe    Maybe I forgot to delete the original environmental light... I think I will have to read the fill light setup article again... thanks!