Render quality problems

[zeppy]

Hi all.
I was trying to work on the cloud levels and I had few problems with rendering; the final render is attached to the post. As you can see, the clouds have many artifacts and some "white points", with that "big hole" in the center-left that represents the light source. Even though I tried to increase some properties, the result was pratically always the same. Oh, yes, I used the low level 3D clouds. A list of the most important parameters I modified:
- Atmosfere Quality -> # samples: 20
- Cloud density: 3
- Cloud quality: 1 (and samples became 700)
- Sun position set to that position (heading 18)
- Render quality: 1 @ 640x480 (anti-aliasing at 3x as default)

Hardware specs if needed:
P4 2GHz, 512MB RAM, Ati Radeon 9550 (256MB RAM), bus clock unknown.

Thinking again about the problem, I guessed that it could be a problem of GI: I admin I didn't turn it on, should I? xD
Uhm... maybe I'll try it later...

Hope someone can help me, maybe telling me what I'm doing wrong or what else I must modify. Thank you all.

[Njen]

Ok, you definately need to increase your atmosphere samples. The immediate giveaway for this problem is grainyness in the haze in the distance. This will clean up up your clouds a little.

I would highly suggest in increasing your anti-aliasing to something higher.

[manleystanley]

Ah yes, the popcorn clouds. I haven't found a way to fix them, and all my clouds look like that. Cloud sampling and atm sampleing just makes it more vivid for me.

[Njen]

Upon rereading your original post, I now saw something that popped out at me. Your cloud density is *very* high. Considering that the default is 0.006, having a value of 3 is overkill. I am assuming that when you increased the density, the clouds looked really dark, so you compensated by changing another value to make it look lighter?

have a quick look at my atmosphere samples page to see what happens when you create clouds, leave everything at default, then change the density to 0.9.
http://www.motionmagnetic.com/terragen2/

Maybe delete your clouds and start over. Do a render with the default values and start changing them a little by little.

btw, in my example of density at 0.9, I had my cloud samples at 1024, and my atmosphere at 64, and I still got grain in the atmosphere and clouds. So the level of grain you have looks right to me considering the density you have.

[firesuite]

Luc Bianco Says he used a density of over 10 for his now famous cloud picture, maybe its not your cloud settings but your atmosphere settings that need increasing if its grainy, also for the whole POPCORN cloud thing i assume you mean that they look blocky no matter where you set your detail sliders, well the only way i found to get rid of the blockiness in the clouds is to turn of acceleration cache for that particular cloud.

[Njen]

Luc Bianco Says he used a density of over 10 for his now famous cloud picture

That maybe so, but the image he was referring to was a huge tower of clouds. Whereas the OP is doing a thin layer of clouds. In all the tests I have done, Cloud Density is one of the biggest contributers of long render times as far as clouds are concerned, as the samples needed to maintain their quality needs to increase dramatically.

[manleystanley]

Hmm, does this make sence? I dropped the edge sharpness way down, and the popcorn around the outer edge of the cloud disapeared.