Yet another Iray Skydome technique

Oso3DOso3D Posts: 14,911

So after discovering how much Terragen would cost to make HDRIs (which wasn't a high priority, just something I'd like to do), I went back to poke at Carrara and HDRIs some more. Still can't figure out how to make good HDRIs with it, HOWEVER...


New skydome technique:

Skydome/sphere as usual. Plug the image into _glossy color_, glossy weight 0, glossy roughness 0, refraction index 1, weight 1. Then line up the sun (either Dome and Scene with no environment map, or Sky and Sun Only), using Lattitude (for height) and Dome Rotation.

Things to tweak: environment intensity, sun disk, sun haze, blue-red tint, and other details to get everything to play right.


I found the 8000x4000 Carrara render I made looked a little artificial in the 2000x2000 render I was doing, so I redid it at 16k x 8k, which is looking better. Your experience may vary, and not all skydomes might be detailed enough for this, I'm not sure.



  • Oso3DOso3D Posts: 14,911

    And here's the result.

    A sphere with a Carrara render in it, set as mentioned above, then Dome and Scene with sun lined up where it should be.

    The car, platform, and figure are Daz objects, the desert, hills, and sky are mostly an image on a large sphere.


    Desert Skydome test.jpg
    2000 x 2000 - 1M
  • FishtalesFishtales Posts: 6,071

    That is very good. Do you have the ground plane turned on? Unless the platform is supposed to be floating it doesn't look grounded as there is no shadow under the side away from the sun.

  • that is pretty good think you may have found the best option for creating some hdris that would fit well with most renders

  • Oso3DOso3D Posts: 14,911
    edited September 2015

    Fishtales: I set the platform to be floating. There isn't a proper ground plane because the image is actually projected on a sphere. If I were going to use this I'd probably put in my own ground most of the time. I'm experimenting with a standard skydome now.


    One note: it's useful to turn environmental intensity down so that you can see the sun disk and line it up, then tweak parameters to get the effect you want, and set Refraction weight to .5 or something to make sure the disk doesn't drown out the image until you get the disk where you want.


    Post edited by Oso3D on
  • Oso3DOso3D Posts: 14,911

    Another tip: if you see a dark blue band 'horizon,' you probably want to lower it so it's not visible.

    I'm testing with a skydome from a product (from A Dungeon Entrance, 4096 x 2048 jpg), and I'm fairly happy with this technique, with two caveats: first, the detail seems a little fuzzy compared to a regular skydome or a proper HDRI, and, second, with a reflective surface there is a REALLY obvious difference between sun and sky. So if you do this, make sure any reflection of the sun isn't visible.

    Example of the problem is visible in the first of these images. Second image is same scene from opposite side, and exposure increased to reflect the lighting.



    Bastion Skydome Test1.jpg
    2000 x 2000 - 994K
    Bastion Skydome Test2.jpg
    2000 x 2000 - 1M
  • are these skydomes and hdris your doing planning on doing 3delight, iray or both? 

  • Oso3DOso3D Posts: 14,911

    This technique is primarily aimed at taking 3DL skydomes and tweaking them to work in Iray. It's not HDRI at all -- my original plans for creating HDRI ran aground when I realized how freakin' much money I'd have to shell out.


  • j cadej cade Posts: 2,310

    You don't need expensive tools at all, just blender! A very rough proof of concept here, for one thing, the render is still grainy but fully done in blender (well I did cheat and add some extra sun in photoshop, but I went to far and that could be tweaked back honestly) Ground also needs some work I spent all my energy on getting those trees to have leaves and a low memory usage. I'm really proud of myself on that front there are actually only three trees and one leaf, as far as memory is concerned. But, yeah only lighting here is .hdr.


    Have I mentioned how much I love blender?

    800 x 1040 - 2M
  • Oso3DOso3D Posts: 14,911

    Any tips on adding extra sun in Photoshop? I was hoping now that I finally have it I could tweak HDRIs to provide proper lighting, but... doesn't seem to work.

  • j cadej cade Posts: 2,310

    Open the hdr and just use the color palette. There should be an option to increase the stops, do this (I've found 10 or so to be good) repaint over your lights with new brighter white. It's pretty disgustingly easy

  • Oso3DOso3D Posts: 14,911

    Any way to do that without blasting out your sun to flat white? Will Levels or anything help?


  • j cadej cade Posts: 2,310

    If you start with a yellow and than up the steps it will be yellow in much the way the sun is (not very if you look at it directly)

  • well I think you've made the right dicision in that this way you have many more options and can cater to so many different styles of render projects that you just can't really do with photos unless you get creative with them in photoshop but this way you can get very creative from hyper realistic to cartoony I still like and will use photo ones but these types would fill a massive gap and be very usefull to many and it'd be nice to have more of and iray hd versions of stuff like in the multiplane cyclorama ande millenium enviroments packs and other backdrops

  • IceDragonArtIceDragonArt Posts: 12,548



  • Oso3DOso3D Posts: 14,911

    Late addundum: I find using a reflective sphere can make it a lot easier to find and match up the sun and skydome-sun than trying to pan around and find them.

  • MynyoriMynyori Posts: 86

    Late addundum: I find using a reflective sphere can make it a lot easier to find and match up the sun and skydome-sun than trying to pan around and find them.

    Since you have better results, I keep getting a black screen when I render a dome item like ultrumarine-ocean using iray in daz. Any suggestions on how I can fix this?
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