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Image Sharing / Re: TB-scene
« Last post by bobbystahr on Today at 12:06:36 PM »
Impressive and great render times for that stunning detail...more crops please and thank you. I'll just bet your chomping on the bit to see the wall....
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Terragen Discussion / Re: Clean Surface Luminosity
« Last post by Matt on Today at 09:49:43 AM »
The main difference between your Terragen test and the realtime solution you referenced is that they use light sources. If you use light sources in Terragen it will render much better in Terragen too. The fact that their lights are area lights is kind of orthogonal to the issue here. For any renderer, the key is that it knows where light sources are (including area lights), but it doesn't know where randomly placed bright surfaces are so it has to use random sampling to find them. For large and moderately bright surfaces this is OK, but for tiny points of intense light it's very, very difficult.

You might be able to get this technique to work using the technique I posted in the other thread (Denis's volumetric stars thread).

As you said, though, what we need in Terragen are light populations. I'm pretty sure we'll add that some day.

Matt
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Image Sharing / Re: Procedural volumetric stars
« Last post by Matt on Today at 09:21:01 AM »
That all makes sense.

You're getting some results here. But I don't think it's because you switched to using a cloud, so I want to make sure you don't avoid using luminous objects for the wrong reason. Bear with me...

In Terragen, light cast from a glowing cloud layer to a receiving cloud layer is calculated using the same method as light cast from glowing objects to a receiving cloud layer. And in both cases it's very difficult to get an artefact-free result for small bright stars. It might work well if you make an invisible set of stars that are much larger than the visible stars, but then you can do that with objects too - that's why I am questioning the cloud method.

I noticed you have bloom and atmo bloom enabled in the render node (maybe from Denis's opening post?), and that's giving you a nice glow. But this works just as well for glowing objects as it does for glowing bright cloud points.

To make sure I'm not crazy, I took your scene file "Stars Offset Example.tgd" and added a Cloud Layer V3 to receive light from the stars, and also added a Rock population for comparison. The lighting effect on the receiving cloud works similarly in both cases (some voxels receive light and others don't), but you have some nice colour variation in your stars. And I do like the idea of using a volumetric function to define star density and colour.

Whichever method you use (cloud or objects), you need the stars to be quite large to produce smooth blotch-free lighting. Much larger than they are in this scene. That means you probably need to have one invisible layer/population for casting light (secondary rays) and another layer/population which is visible but does not affect secondary rays. Or just use bloom and/or atmo bloom which works well with very small points.

I've attached some .tgd files:

tgd #1 is just a simple comparison between glowing clouds and glowing rocks, showing that there are similar problems in both cases (higher cloud GI settings and voxel settings might be able to turn this into a much better render).

tgd #2 uses two rock populations. Invisible rocks are much larger so that the cloud layer finds it easier to sample them for lighting. The visible rocks are smaller and have "visible to other rays" turned off so that they don't create blotchy lighting problems.

The best way to handle this in some future version of Terragen  8) will be with light populations (which you asked for in the other thread, and I'm pretty sure we'll add that some day).

Matt
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Image Sharing / Re: TB-scene
« Last post by Kadri on Today at 09:02:08 AM »

Looks nice. I would like to see more.
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Image Sharing / Re: World with Three Suns
« Last post by WASasquatch on Today at 08:19:15 AM »
This has a really nice color scheme for the atmosphere, I like it a lot.

It's ironic you posted this today on facebook just a few posts away from an article from Space.com about Binary star-systems possibly not able to support atmospheres on planets.
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Terragen Discussion / Re: Clean Surface Luminosity
« Last post by WASasquatch on Today at 08:17:59 AM »
All your answers to why it's possible are in the notes of that project. For example:

"Area lights give great direct light results, but their shadows and scattering in the fog are very rough approximations in this project."
"Direct light soft shadows are implemented using PCSS - the technique was good enough for our specific cameras, but in general isn't great and the settings are difficult to tweak. Real time shadows from area lights is still an open research topic."
"The scattering contribution in the fog is limited to the same frustum and not physically correct either."
"Tube lights use a very cheap and practical solution to approximate area lights, but the resulting quality is much lower."

In other words, like all realtime solutions with current technology, they are "cheating" heavily. :D

That being said I recognize that the results can often look very good. The problem is they are not accurate or fully realistic. We aim for a higher standard of realism but yes, it does take longer. I do wish we had a better ability to find an in-between, with fast and reasonably realistic results, accepting some compromise. Right now the Terragen way is pretty much "max realism or nothing". ;)

- Oshyan

I still think this is really an issue having to do with no real distance control, leaving luminance either having to be extremely bright, or it doesn't function at all (besides the surface being bright with no casting). If there was control of the distance light was being emitted from the surface, it would probably work fine. Using the surface displacement as vector alignment for light direction, or if none, just straight on the axis of the shape (like a sphere). When you look closely, light is working just as it should be, and is scattered via the cloud, but it's just probably a 10000x too bright, but with current setup, it's either too bright, or literally non-luminous. If you use a light source, and up all the settings to ridiculous extremes, you get the same result as a luminous surface with high luminosity.

Looking forward to some sort of solution to this as it's always been a limitation I recall for the last 10 years or so really. There are countless ideas I've had that are limited simply by the fact the only light sources are technically a light-ball, spotlight, and a fixed sun, and are completely reliant on user control. Nothing using a series of lights is possible without manually doing it, something that has been addressed in every rendering program I've used so far, including light arrays, which I guess would be populations in Terragen with the added ability of columns/rows as apposed to just random seed based. So far it all seems to be a simple process to incorporate in future versions to have light populations like the shader array + population, especially like the shader array as it's just instances and locations and the math done for the user instead of having to do all the calculations or positions.

Totally understand wanting to be realistic and not "cheating", but I feel the functionality is almost there, just needs to be refined. Though the option for "fake" realism never hurts. Similar to all the other fake options, stones, clouds, etc, and some of the fake options you just have to do to really achieve some things in TG. Just the ability to create relatively smooth luminous light itself may bring in a whole lot more professionals for cinematic use, as watching makings of on movies and world, they often incorporate planes with random lighting for the "Moth Effect" to attract audiences. Or for ambient effects like a lit plane behind a block of buildings to simulate light pollution from the other street(s). And I don't mean the go-to lens flaring.
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Terragen Support / Re: Cloud v3 seam between render tiles?
« Last post by WASasquatch on Today at 08:13:53 AM »
You also can't populate them inside a cloud in random volumetric positions.
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Image Sharing / Re: Procedural volumetric stars
« Last post by WASasquatch on Today at 07:55:21 AM »
This isn't a good way to render small points. Clouds are rendered using ray marching, which is great for slowly changing functions such as clouds but very bad for searching out tiny points of light in a vast volume of emptiness. It would be much better to use a populator to scatter luminous objects. If you're trying this volumetric approach to try to work around limitations of casting light from the populator, then you need to know that those limiations will also apply to a cloud-based star function.

Matt

As discussed in the luminous surfaces topic I made just recently, objects and surfaces giving off light pretty much break Terragen and are of no use at all. Needs much work. At the lighting scales (since there is no light distance control) you have to break TG with intensity before the look you want even starts showing (under the broken diffused pixels). Also, the light casting was either "On" or "Off" when playing with the intensity, which, when "on" was just ridiculous bright and the light distance goes on forever (that you can see). Additionally, ramping up luminosity to scales that produce good glows that cast, cause the object to turn solid white.

This approach, however, gives off glowing light without creating a million scattered pixels and weird lighting artifacts.

These aren't really tiny points of light, they are in fact clouds, that also glow (density plus ambient/modulator). And they're pretty large, and can get larger. The point of using this is using actual stars to light nebula cloud forms, or galaxies, etc, or in a testing project, an actual "star layer" well above planets and their atmospheres. Simulating stars in the sky on a small scale. Doesn't look half bad if only there was light dampening, when light sources are not as luminous as another, they don't shine basically (like our own sky and stars disappearing during the day)

Denise has shown us that Terragen can create near perfect (to the eye) nebulas compared to any other program I have seen, where nebulas come of surreal or just plain fake. Improving it with volumetric stars you can pan around would be awesome, both in animation and just stills.
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Terragen Discussion / Re: Base wispiness
« Last post by N-drju on Today at 07:53:46 AM »
Can't it just be done with the distribution shader Ulco? Like you advised me to do?
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Image Sharing / Re: TB-scene
« Last post by N-drju on Today at 07:51:16 AM »
Good job Ulco. As per GI cache, I once saved a cache file and then used it on four separate render crops. They did not match at all. ::) So it's a good solution, not always. Strange but true.
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