problem with low level cloud effect

Started by king_tiger_666, December 23, 2006, 09:45:48 PM

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hi.. I just finshed rendering this image, everything was on maximum but i don't know why the clouds in the lower right corner looks like its pixelated?.... anyone got any idea of why this is rendered like this when the rest of the cloud looks alright

render time 44:13:41s 3652623 micro triangles
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Looks like a problem with the Acceleration Cache. This is implemented to speed up cloud rendering but it sometimes causes artifacts like that. You can turn it off in the Quality tab of your cloud layer but it will make render times even longer.

What were your other renderer quality settings at and what are your computer specifications? That seems like a long render time for the image.

- Oshyan


its a p4 2.8ghz 1gb ram..  all settings were set as high as the slide allows.

both 2d clouds, and 3d clouds were on max settings, and the render was also set on max settings

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There's your problem then, presuming you're including the Global Illumination settings. Just turning up all the values for any "final" render is not a very good idea, even more so than in TG 0.9 because there are so many more settings, some of them with subtle effect on the rendered output (or none, depending on the scene), but dramatic effects on render time.

Here's some info I originally posted on Ashundar which may help you get more "sane" render times:

First and of greatest importance do *not* assume that the max on all sliders is the best, or is appropriate for all renders. This is particularly true for the Global Illumination sliders which have inappropriate maximum values. 11 for GI relative detail and sample quality is really an insane value. As a TG2 tester I have never seen nor heard of anyone actually using this value for a finished render, and most people who use GI in practice use values between 4 and 6. For basic scenes 2-3 is fine in fact.

Now on to the rest of the info about quality settings. :)

For general detail setup, to know what to change when trying to improve image quality, follow these rules:

Do a test render with general default quality first.

Remember that there are multiple places where detail settings are changed.

Also keep in mind that there are lots more detail settings than before and they affect different aspects of the scene. Never assume that you just need to turn everything up or on for best results. Some settings are only necessary for certain scene types and will just slow down other renders.

If you see noise in your clouds, increase cloud samples. If you see noise in the atmosphere, either below or above the clouds, or in light rays, increase atmosphere quality.

For atmosphere samples I wouldn't go above 64 unless you have lots of rays, in which case you might go as high as 128. Don't go above that though as you get diminishing returns for very much longer render times.

Cloud samples could be put as high as 256 in some cases, but 128 should be a normal maximum to give good results. Much lower settings should usually be fine, especially for default cloud settings. The *taller* your clouds (higher "depth"), the more samples will be needed for good quality.

For clouds and atmosphere the quality is defined by number of samples and is indicated by the level of noise. If you don't see noise in your clouds or atmosphere but want higher "quality", don't increase samples, just increase Detail in the Renderer.

Once you get a good level of noise-free results with clouds and atmosphere at 0.5 detail you can adjust other settings.

If your lighting seems to need more detail or accuracy you can try increasing GI detail. I would try 1 level at a time, go from 2 to 3, then 3 to 4 if it's not enough. If you don't see noticeable differences in these changes then your problem probably lies elsewhere!

Only enable GI Surface Details if you are doing a render close to the ground or with objects and the shadow detail on the ground or near objects is not high enough. This will cause a major render speed impact and is usually not necessary.

If you see jagged edges on areas of high contrast (terrain against the sky for example) or object edges, increase Antialiasing. Note that in the free Technology Preview you can't go above the default of 3. For the Terragen 2 pre-purchase (available soon!) you can use whatever value you want, but I would generally not go above 8, and normally 3-5 or 6 should be fine. (note that some people have had good results increasing AA to very high values - 20-30 - and then using lower Detail values, like 0.5)

Finally, once you have a pretty good-looking scene and all your other detail levels have been adjusted appropriately, if you still feel that the *overall* scene lacks a bit of detail, then you can consider increasing the main Detail setting. But again I would recommend adjusting other detail first until you have a fairly consistent level of quality across the whole render. Even if it's less *overall* quality than you want, the main thing is that it be consistent - noise-free clouds, decent surface detail, good lighting quality, etc.

Increase the main Detail setting incrementally - don't just jump to the maximum. Each 0.1 increase will have a big impact on render time as well as quality, but the render time impact is generally greater than the quality impact. 0.5 actually provides pretty good detail for many scenes. 0.7 or 0.8 can be a good detail setting for final renders while still saving time over 1.0. You might even use 0.9 for almost the same detail as 1.0 and less render time.

Don't simply assume that you will always be able to see the difference because 1.0 has more detail than 0.9. TG2 renders *sub-pixel* detail, so it is not necessarily the case that you would see the difference between two high quality render settings (0.9 and 1.0 for example).

That's it for now. I hope that will help give you a better idea of how to get reasonable render times *and* quality. :)

- Oshyan


I love coming on here to ask a question, and see it already answered. Working simple landscape with trees and sunbeams. The clouds looked like popcorn, and the rays were extreamly grainy. I've rest a few things as per this advice, and am waiting on a test render.
Thanks Osh. :D
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can you tell a green field, from a cold steel rail? a smile from a veil?
do you think you can tell?" P.F.