iRay & RTDNA Atmospherics Fog
nonesuch00
Posts: 18,120
I have RTDNA Atmospherics and am trying to use the fog out of that product rendering in iRay but I see no fog. How do I get it to work? Thanks.
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The various fog effects in the product, as you may have discovered, are created using a fairly complex series of planes to which transparency maps are applied. In 3Delight the transparency maps are plugged into the Opacity channel. You can view the planes (which is quite enlightening) by opening one of the fog effects in DAZ Studio, and then removing the transmap from the opacity channel. I'm not an Iray expert, but the fog effects should work by ensuring that the transparency maps are plugged into the cutout opacity channel as I would understand it.
OK, I will try that. That's similar to how I made ghost dragons.
Thanks
Well darn, they are in the Cutout Opacity already. Maybe they just need strengthened. Hmmm, they are already at 1.0.
Maybe the fog is one of those effects that gets painted on near the end of a render process? I have slow CPUonly renders so I will just have to wait and see.
Yeah, I fired up my workstation and loaded a scene, then added the fog to see how it worked. If its any consolation, my scene has been rendering a little over an hour and its still only at about 50%. And that's on the GPU! I don't know how much of that is due to all the transmaps because there are other elements in the scene I grabbed randomly that might be adding their own complications. Anyway, we'll see. I think that you might be right about the opacity strength, though - I hate having to wait so long just to find that out. If so, we should report back and we can each try different settings to test the effect, perhaps?
I added some alterations to my Surfaces settings and it's now showing up much better however by the time the render finishes maybe the fog alterations will be too strong. They show up stronger even in the openGL texture preview port.
I'll post the 6 for shader duf presets I'll save in 3 days when this is done if you want them although after 6 iterations it's, let's say, 'pixelly' looking, not that fog doesn't create that effect itself somewhat...
The RTDNA Atmospherics rain works fine though although it looks like it was frozen in times as if taken by an ultra fast camera. I did change the surfaces using the UeberIray or MEC4D iRay shader vol 2, although the original subplied by RTDNA converted and works fine too.
Well, mine finished after almost exactly 2 hours (about 92% converged), and, with the setting at 1 the fog is visible in the render, but is extremely faint. Noticeable, but faint. I think a setting of 2 might do it, but I want to let things cool down before giving it another go - nothing like an Iray render with the video card going full tilt for a couple of hours to heat up a room!
I didn't know it goes above 1.0 so I will have to try higher values too...I have a render now that I like the looks of but it will take a few days to get acceptably converged although not near what I have the converge limit set too.
You'll need to click on the little gear icon in cutout opacity, nonesuch, to bring up the settings dialogue. It is set to use limits by default, with the default limit set to 1.0. I left limits set to on, but changed the upper limit to 3.0, which allowed me to adjust my settings to 2.0. You will need to either remove limits altogether or do similar to what I did to get the slider to go above 1.0. I dropped the image size significantly to reduce render time and the result using a setting of 2.0 was much improved.
I also stumbled on another factor that should have been obvious from the getgo. The fog prop consists of a complex array of small planes arranged across a surface centred at the origin. In my scene I had used a backdrop positioned a short distance behind my subject figure, with both close to the origin. The camera itself was positioned a relatively short distance in front of the subject. The effect of this was to inadvertently place about a third of the fog planes out of sight behind the backdrop where they didn't come into play, while at the same time positioning some of the planes beyond the camera in front where they, too, were out of play. So, to test the effect, I compressed the fog by reducing the scale along the Z-axis until all the planes were between the camera and the backdrop. I left the settings at 2.0, but, after completing another render I found that I probably could have achieved acceptable results under these circumstances by leaving the settings at the default of 1.0. Of course, that situation would apply only to my particular scene, but it does raise the possibility of achieving acceptable results by playing with the prop scaling, and.or by adding in additional fog props. Bottom line is that the fog will work in Iray and there are options for tweaking that will allow you to achieve a variety of effects.
The following is the unscaled fog at 2.0:
Thanks, that looks good. I repositioned my fog too but didn't compress it on the Z axis. Since my scene was outside, I also changed the transluncy weight, made the transluncency color slightly blue, added refraction index to that of water, and added emmission color of very slight blue with a very weak luminance of 25 candela/m2. 15 hours later though I am only on iteration 167 at 0%.
I tried applying Will's WTP2 procedural cloud shaders but those were way too much CPU time for the so many planes in my scene. I am using all 6 Fog presets so that's a lot of fog to render.
One more thing that I didn't mention, that you may have already discovered yourself: the camera position/orientation will also have an influence on the appearance of the fog. My guess is that the props were designed to be used with the camera oriented with the focus straight-on to the default position of the props. If you load the props and rotate the camera about the Y-axis, you will notice in the viewport that the effect of the fog changes with the camera position. Parenting the props to the camera should allow you to maintain the desired effect regardless of camera position.
Hmmm...I probably could of put triple the number of rain drops strung out deeper along the Z axis on my current render. Oh well, I'll try it on the next render.