Rendering nice cubemap skyboxes

armagon

I'm working on a Unity level and i've trying to render a nice cubemap skybox to create more detail to the scene. I have been using Terragen since forever, but the result is not very nice. It looked good back in the CS 1.5 days, not so much now.

Which tools do you guys recommend to render nice cubemap skyboxes? With decent terrain generation and option to add more detail? I have tried the Vue xStream demo, and the results are great, but there is no option to render cubemaps of the scene. The built-in feature just exports the sky texture, not the scene in cubemap format.

EarthQuake

You say sky texture, do you mean a long/lat panoramic projection? If so, try using Lys to convert it to a cubemap.

https://www.knaldtech.com/lys-open-beta/

If not, post some images of what you have and what you want.

armagon

I mean something like this: http://eyeonmanual.com/wp-content/uploads/2011/10/F6-example_horizontalcross1.png

I wanted to render the whole scene in 360º, but export it in that cubemap format. But i'm looking just for a solution that allows me to create a cubemap, but knowing which tools artists use to create cubemaps, sky spheres and other environment tricks.

I'm trying to create detailed and interesting horizons, like in these screenshots:

http://2.bp.blogspot.com/-yKQZj-u71jQ/URgyY1KbmMI/AAAAAAAAANY/6LJSjkeuYFs/s1600/vallahla01.jpg
http://www.rgbfilter.com/wp-content/uploads/2010/08/HaloReach-Forge03-Island.jpg
http://images.eurogamer.net/2013/articles//a/1/6/2/9/4/7/9/BF4_PC_005.bmp.jpg
http://i.imgur.com/a2ZiFbG.jpg
http://thegamingliberty.com/wp-content/uploads/badcompany2screen31.jpg

Eric Chadwick

We have a few resources here
http://wiki.polycount.com/wiki/Cube_map

I've seen many artists start by photographing panoramas of real clouds, then layering other things on top using their 3d software of choice, plus Photoshop.

The trick with painting cubes in Photoshop is to never paint near the edges, because you can't paint the linear distortion properly. You can convert between cube and pano layouts, to paint more, but you end up losing a bit of image quality.

The best way for me is to layer stuff in a 3d app, like Max or Maya, then render that out to a cube format.

armagon

Is there a camera script that you use in 3DS Max for exporting a cubemap? Also, which renderer do you use? VRay?

Eric Chadwick

Wiki page has instructions for rendering cubemaps in Max.

I just got V-Ray for a job this week, so no, I haven't. Also just started using mentalray.

I've used the default scanline renderer in Max for cubemaps. Works fine for compositing layers together.

I also learned you can't use the Reflect/Refract map (see wiki) with V-Ray, so if you want to use that renderer you have to output it otherwise.

hooblegooblin

CubeMapGen from AMD can read in cube cross images and export to cubemaps.

CubeMapGen: http://developer.amd.com/tools-and-sdks/archive/legacy-cpu-gpu-tools/cubemapgen/

armagon

Actually, i'm looking for tools that help me create those cross images.

EarthQuake

I think Lys can export cross images. Try it out, its in beta/free atm.

hooblegooblin

CubeMapGen is also capable of exporting cube cross images, besides importing them.

armagon

Export from which sources? Vue? 3DS Max? That's my point.

hooblegooblin

What is the format of the image you are trying to convert into a cubemap? Is it equirectangular, or something else?

Secondly, what is the output format you desire for the cubemap?

If you are working with Unity all you need is the six separate images corresponding to each view direction.

Joost

Render equirectangular sky in vue and then convert that to cross format with Lys. I used to use pano2vr but that's not free.

I wouldn't include anything that isn't part of the sky though. Things like mountains are best kept separate, even if they're just simple planar projections. But with current engines you can afford to just use geometry for everything.

Eric Chadwick

Don't forget too that you can use the Texture Importer in Unity to convert to a cubemap
http://docs.unity3d.com/Manual/class-TextureImporter.html

It says you can import a cubecross layout, but I haven't tried that so not sure how that works.

armagon

komaokc wrote: »

Render equirectangular sky in vue and then convert that to cross format with Lys. I used to use pano2vr but that's not free.

I wouldn't include anything that isn't part of the sky though. Things like mountains are best kept separate, even if they're just simple planar projections. But with current engines you can afford to just use geometry for everything.

Thanks for the tip, i'll try to render my Vue scene with that.

However, why do you say it's not good to use buildings, mountains and so on? The engine i'm currently using (Torque 3D) is not really powerful, so, i'm not sure if rendering actual meshes far-away would be a good option.

Eric Chadwick

Three reasons: the mountains or buildings are sharper if using geometry than if they are blurry pixels in the skybox, you can get some parallax between them and the sky, and if your time-of-day changes then they can show that lighting change (while the skybox can be either faded to another one, or else just tinted a new color).

Shadownami92

Personally I've actually set up my own panorama baker in Blender, so I can set up a basic scene, bake as a panorama texture, then I can use Lys to make irradiance and do tweaks and all that. It's basically just a mirror ball that is uv unwrapped to be a rectangle and then I bake the full render to a texture.

Then for unity you can use Skyshop or Panorama to Cubemap https://www.assetstore.unity3d.com/en/#!/content/13616 to set up the proper cubemap format stuff form the panorama.

Eric Chadwick

Also check out the Panorama Exporter utility in 3ds Max.
http://help.autodesk.com/view/3DSMAX/2015/ENU/?guid=GUID-EBEA879F-4067-46E0-8566-F7AAD11FEBE8

armagon

Well, i'm planning to render a high-resolution skybox in order to achieve more details. I want some spaceships, different moon's an so on. I'll try to add terrain in the skybox and leave buildings out of it, and see the results.

Thanks for the info, guys!

Chimp

OP: I've used Vue for game cubemap skyboxes - you need to set the camera up, rotate and export as square aspect images without distortion and flares etc, there are many tutorials for cubemap skyboxes from vue on google - I'll look one up when im home but you should go digging yourself too, it was the first thing i searched when I had a Vue license.

EarthQuake

I would leave things like spaceships out of it for sure, you should make distant model for this stuff (even if low res/quality) so you can proper parallax. Something like a moon should be fine in the skybox, unless its huge and taking up half the screen, then you probably want it modeled out.

Eric Chadwick

Also, remember that big skyboxes use a lot of texture memory. Six 1024's are going to use a huge chunk of your memory budget.

You can try a compressed format like BC1 (DXT1), but you'll start seeing a lot of blocky artifacts on the edges of your planets, nebulas, suns, etc.

That's another reason to go lower-resolution for the cube, and use it only for distant less-detailed content, like clouds and really hazy things.

Making a good skybox has it's own set of challenges!