Panorama to Skybox

dpadam450

Anyone know of a 1-click button that can turn a panorama image into a skybox? Or some other simple tool? And I don't mean that junk I-phone app, I mean taking skies from cgskies.com or hdr-skies.com.  I've done quite a bit of researching but found nothing other than a couple tools that stretch the cubemaps to pure junk. Otherwise I'm just going to program a tool to do it.

Steppenwolf

The skies on cgskies are in the right format already, kinda. I usualy just resize them to 2048x2048 or higher and throw them on a sky sphere that's uv mapped accordingly. I guess they can be rerendered onto a box somehow but keep in mind that a sphere has some advantages (less texture count, draw calls, less overall texture resolution requirement). So i would always go with a sphere unless your engine has some problems with it. I know in source engine spheres cause some rendering troubles but anything newer then that should be able to take a sphere.

dpadam450

Do you have an example UV layout, I've never seen this work without the poles being screwed up.  With a sphere I've only seen it work with some touchup to blur out the poles.

Steppenwolf

There is minor artifacts on the pole but it's not very noticable. The pros outweight the cons imo. Seen this uv approach on multiple occasions including the racing game demo from UE4. This is one of the skies from cgskies. It's one of the 15000x7000 or something skies resized to 2048x2048. Looks pretty squashed on the texture but unsquashes on the mesh back to the correct proportions.

dpadam450

Ah, I never though to split the pole vertex like that. I'll give it a try.

EarthQuake

2048x2048 doesn't make sense for a sky hemisphere, 4096x1024 will use the same texture memory but will map much better to hemi.
Correct:

Wrong:

You'll get much better horizon detail with 4:1 vs 1:1, for the same amount of pixels/memory use.

EarthQuake

Oh and, Lys can do all sorts of panoramic conversions: https://www.knaldtech.com/lys/

Steppenwolf

Good point EarthQuake. Saw the use of 1:1 textures when i researched the topic myself and never questioned it to be honest.