spherical render

[Dune]

I was asked to do a spherical render (for some phone app), and never having done one; are there any issues I need to take care of, bugs to circumvent, or plain recommendations? Or would a cubemap be better to use?

[pokoy]

There may be artifacts at the bottom or the top in TG with spherical rendering, mostly only a few pixels, it should be easy to retouch them in PS.

As for different panorama layouts (equirectangular, cube maps, H and V cross), there's a nice and inexpensive program called Pano2VR which will convert from and to most common layouts. It's fast, customizable and works with EXRs, too.

I'd always render at a higher resolution than what's needed since converting may result in pixel stretching in some places. Also, try to avoid converting forth and back several times between equirectangular and cube for example.

[paq]

Hi Dune,

I'm not sure if it has been fixed, but it's better to raytrace the atmosphere (defer atmo/cloud on) to avoid pole problem (missing pixels like pokoy describe).
I do prefer stereographic projection, aka fisheye in terragen, even if you want to reproject it as cube map or spherical.

The big advantage with stereographic is that you have full resolution on the pole.
https://www.behance.net/gallery/32096159/Terragen-stereographic-skies

In fact you even have more resolution on the pole than the horizon.
It's also the kind of image that is easier to manipulate (paint-over) in photoshop, because there is not really stretching area, and there is no seems (compared to spherical)

It's the perfect projection for first person shooter, maybe a little bit less suitable for racing game where all the attention is on the horizon line.

Stererographic skies need to be reprojected on an half sphere, UV's are just made using planar Y projection, then relaxed.
I can provide you a simple model poly sky model with the right uv's if you want.

[AP]

I thought the pole issue was fixed already? Make certain your camera rotation is all zeroed out looking perfectly straight at the horizon only.

[Dune]

Thanks guys. I did a straightforward render yesterday, which turned out nicely. Can't post, though, as it has TG alpha stuff in it. I don't think any pixels are missing, so the bug seems to be taken care of, indeed.
I'll have a look at Pano2VR. I have no smartphone or tablet, so I need some device/software to see what it looks like on pc.

I don't exactly understand what you mean by stereographic and the projection part, paq. It sounds a bit elaborate. I would very much appreciate a short tut, before I have to invent the wheel again!

[AP]

No problem. It's good to hear that issue was not present.