Iray Sky
Taoz
Posts: 9,724
in The Commons
In Iray, with Sun-Sky Only and Draw Dome, there is a skydome with a blue sky. Assuming that it's being generated by an image, is there a way to replace that image with one that has clouds or other stuff?
Daz 3D is part of 
Connect
DAZ Productions, Inc.
224 S 200 W, Suite #250
Salt Lake City, UT 84101
Licensing Agreement | Terms of Service | Privacy Policy | EULA
© 2024 Daz Productions Inc. All Rights Reserved.
Comments
I am pretty sure the blue sky is done programmatically by applying a blue hue and evening it out in some way to prevent a uniform color. I am not a fan of the Sun-Sky Only sky either, I find it often looks almost white.
One option is to render Sun-Sky first, but with draw sky switched to off, so that the sky is now transparent. Let this render run for as long as you normally would. Now switch to Draw Dome using a HDR with clouds etc, and render again, but this time only rendering for a few minutes as the sky will not change much after the initial period anyway. Finally lay the first image on top of the second using Photoshop/Gimp/Other photo editor, and you have a decent looking sky with the rest of the scene rendered using the Sun-Sky option.
Another option is to use Stonemason's IRay cloud's product to scatter a few clouds into the sky.
OK, will take a look at the options. Thanks!
...yeah the fact that 3DL skydomes (which I have a fairly nice collection of) block the Iray sun is a real pain as you cannot turn shadow casting off in photoreal mode. Substituting a photometric light really doesn't work the same as the shadow softness doesn't vary with height from the ground/surface plane.
For different skies, I usually resort to flat planes with high quality photos or skies I create/render in Bryce/Carrara then save as a .jpg. Just have ot make sure that nothing casts a shadow on the plane itself. Not that fond of HDRIs as many of the free ones are either not high resolution enough for the size of rendering I do or the "sun" is too weak.
Thanks, will try the flat plane option to see how that works. I finally managed to find an Iray skydome in my library that didn't have some kind of environment attached to it: Dimension3Ds "Skies Of Iradiance". Works pretty well, except that it suffers from the same problem as most other skydomes - way too many clouds on almost all the sky maps (about 80% clouds and 20% blue sky). I'd like to see some with the opposite. I found one in Sedors "BWC Skies 2" but that's for 3DL so it has no sun and needs to be darkened a lot using gamma correction to look reasonably good. The boat in the sample here doesn't look as good either with it as those with the Iray dome, probably because it's not a HDR. On the other hand, I think the boat is too bright with some of the Iray domes, but that maybe because it's white. The first one here is the BWC Skies 2 3DL dome, the others with D3Ds Iray dome.
...when using a flat background image, make sure to use Sky and Sun environment setting.
These are epic..
http://www.daz3d.com/iray-worlds-skydome
http://www.daz3d.com/iray-skydome-super-pak
(2nd one is an add-on for the 1st)
..again while nice, most of those have fiarly heavy cloud cover. it would be nice to find some skies more like this:
The beauty and purpose of an HDRI skydome is that it produces lighting that is consistent with the sky image that it displays. Why would one want to have the lighting from one skydome but a sky image that that doesn't conform to the light it produces? This runs counter to whole idea of HDRI lighting.
I think what you actually want is an HDRI skydome that simply has less cloud cover than the ones you have. That is what you should be looking for.
...again, the trouble I've had with some HDRIs is that they do not capture the full brightness of the sun, and in the case of free ones, the resolution is often too low particularly whne rendering a scene at high pixel dimensions.
Most indoor HDRIs have a dynamic range of 12 EV however for outdoor settings they may need to have a range as much as 24 EV (EV = exposure value, Dynamic range is the number of 3 EV gaps between exposures) depending on sky conditions. This is often how HDRIs can end up with a sun that isn't as bright as it is in nature along with shadows being somewhat indistinct or weak (both being a contrast issue due to an insufficient Dynamic Range)
For a "clean" backdrop without blurring, the higher the resolution, the better. This of course increases the memory load. A 16,000 x 8,000, HDRI file will be over 1 GB in size which can be an issue for GPU rendering.
Not everyone has access to the photographic equipment and software required nor has the skill to create a good HDRI environment, so most of us have to rely on premade ones. Unfortunately so far, as Taozen pointed out, most of the HRI's available here in th store tend to be fairly heavy on the clouds and/or include ground plane scenery, leaving us with with a choice of a very "busy" sky or one that is clear blue and featureless (the default Iray Sun-Sky setting). What we need is an Azure Skies like set (which was an expansion for the LDP2 plugin that included less cloud cover) for Iray.
Speaking of LDP2, the plugin managed to do pretty much the same as an HDRI, using a skydome, a large array of very low intensity distant lights for the ambient illumination and a high intensity distant light for the sun that all rotated with the dome (there were also duplicate UE settings). Of course in 3DL you can disable shadow casting for the dome (which was the default for LDP) which cannot be done with Iray in photoreal mode.
...agh it's 01:20 and I my brain hurts thinking about all this. Need to turn in.
So this is a combination of the two products I linked above..
The sky is x13 Skys Puffy from the base set, rotated to 5.0 (to show the least cloudy part), the land is Green Hills from the expansion, the water is Ripple Water 3 from the expansion, the sun is set to -1S Mid Front - Color 5000k (Day) - Lm2 44 (Bright) all setting in the base set. The ship is Medusa by Faveral. It still has some clouds but it's not covered in them.
This took 13 minutes to render, btw, and it's a very high poly model.
Thanks, I already have both though, but they include ground plane environment - I'm looking for a plain skydome without environment and with a variety of different skies, from plain blue to heavily clouded (most seem to only have the latter).
Yes, that's also what I'm looking for.
Yes, that is what I'm looking for.
One thing to keep in mind when using a flat background image is to choose one with some level of perspective... Not necessarily a narrowing vanishing point type, unless it's a really great distance being simulated, but one at least where the clouds tend to grow smaller and more squashed as they near the horizon.
Among the three images in Kyoto Kid's post above, the bottommost image best illustrates that.
I don't know if anyone can use these, but I went and uploaded a couple of sky images I captured out on the ocean a few years ago... They weren't the greatest quality because of the camera, but if you can use them they are here (the thread for uploading images)...
http://www.daz3d.com/forums/discussion/59113/an-ot-thread-for-images/p5
I tried to keep the horizon low for maximum sky, but one is halfway up... There are some dusk images too... But the camera didn't like low lighting.
If I ever get a good quality digital SLR, I'll take more sky images (and not from a moving ship)... I live near the Atlantic and when you go out to the beach, especially some of the barrier islands in the winter, there are some awesome skies and sunsets.
Examples of the pix...
Yes that looks great, but unfortunately the ground plane environment gets in the way if you want to use the skydome with another environment.
When using an image with ground at the bottom lower the horizon by using a negative setting until it is hidden.
Will give them a try, thanks!
If you mean Horizon Height that setting is not always accessible when loading a skydome. It's not with Skies Of iRadiance for example.
Well I actually found a way to remove the ground plane environment in Iray Worlds: on the Scene tab, make the IR-Base invisible, if there is a gap between the skydome and the water/ground use Y-Translate to lower the IR-Base.
Yes, I realised the wording was for Sun and Sky but it also works in Dome mode too. Set Ground Position to Manual and set the Ground Origin Y to a negative number. You can also use the Dome Orientation Z setting which rolls the Iray dome.
OK, for some reason this doesn't seem to work with Iray Worlds though, it only responds to the settings under Parameters.
I don't have that set but can you select the Skydome in the scene and then lower it with the parameter tab so that the ground is below the horizon and put another ground plane or water plane to hide the ground that comes supplied?
You can select the Skydome and lower it but the ground plane environment doesn't move with it. But like I mentioned in a previous post, you can hide the whole ground plane enviroment in this set and still keep the Skydome just by making the IR-Base on the scene tab invisible.
What happens if you pull the Skydome and the Sun (which I assume is just a light) out of the Base and then delete the Base?
Nothing blows up and it works fine, the sun is a sphere mesh light.
...but what about cast shadows? A large sphere mesh light would have very diffuse shadows while a smaller one would create crisper shadows however they would appear to radiate from a point rather than being more parallel. Also in the samples above, the "ground plane" is water which has reflectivity and refraction so shadows do not appear to be as strong as they are on land. Would like to see some examples on land based ground planes.
Here's how the shadows look with the default setup:
You should be able to find something suitable in this thread: https://www.daz3d.com/forums/discussion/57531/list-of-sites-with-free-hdri ;
The sun positions in Iray Worlds has a confusing notation.. is there a good explanation somewhere? Also it would be nice to fine tune.