Rendering Skyboxes. Problems with lighting.

[Draigr]

I've been doing a bunch of 360 panorama shots for a skydome in UDK. But all I'm getting is this:




As you can tell. The process is fine, explained below, but the rendering is not. What's up with the lighting changing on a 90 degree angle switch? Please don't tell me Terragen simulates the light reflecting off of the virtual camera lens....


Either way. this is something that's been discussed before, but after hours of searching for solutions, I got nothing. So please, I need help with this, it's a time urgent kind of thing.

And yes. I've tried switching GI off. That's with it on. But the effect is exactly the same, except everything turned green. But that's just atmospherics and lighting, I can deal with that.

So I'm basically using the 6 shot/slap onto cube/bake to sphere/save image method to make a 360 degree panorama. Each angle change is 90 degrees, and the FOV is 90.

For those a little confused. I'm using this tutorial here as a base: http://lightfeather.de/lf/documentation/skydometutorial/Skydome.html

But because the actual method is faulty, I eventually figured out that reflecting the normals of the outer sphere fixes the problem of the render not baking anything.

So far, this is the only process that works to get a panoramic 360 image fit for a skydome in UDK. Image stitching just ends up with the stitching program crapping itself and wondering what it's doing. And manually doing all the points still leads to the image program crapping itself. I've tried Photoshop CS5.1, PTGUI, and Hugin. All of them couldn't figure out who to do with the pictures, mostly because there's two images for the floor and ceiling shots I think.

And before you mention it, yes, the images for the stitching programs were shot using 110 degrees for the Horizontal FOV.

Bla bla. Long story short. I've only got one method that works, if anyone could tell me another way, I'd be happy to hear it.

Although the process I'm using right now works quite nicely, once I figured out how it works...

[freelancah]

Have you checked this tutorial? http://forums.planetside.co.uk/index.php?topic=11608.0  It's usually a good idea to render overlapping images to address this issue

[rcallicotte]

Please let us know how this goes.  I'm always on the verge of trying this and never quite get around to it.  But, your images look brilliant and this could be a great time to learn, if you will keep us in your loop of discovery.

[Draigr]

@Freelancah: Yup. That was the first one I tried. PTGui runs and hides in a corner somewhere on the computer. I just get this screwed up mishmash. It can barely connect the dots, and doesn't actually work when I do it manually. And I tested with a set of images that had very easy to spot and use marking points. Both manual and automatic.

It just doesn't work.

And yes, overlapping images were used.


@Calico: Will do! I'll be doing an updated tutorial once I get the kinks worked out. I've spent the last week or so with a coupla days of intensive rendering and problem solving just getting this far. It takes a while to do these things.

[freelancah]

Hmm that is strange indeed. I've rendered tens of skyboxes with similar method and have had no issues yet

[Draigr]

Well. If you can get it to work, let me know and how I can fix it:

I've uploaded the files here:

http://www.mediafire.com/?vxltuejl1li519w

Obviously I rendered in exr, but they're rather large. So these are jpgs.


They're also pretty much the renders terragen spits out.

I'm using FloatingPoint's camera rig, so...

[JimB]

I've had exactly the same. The lower the sun the greater the disparity, I've found, probably due to the huge differences in light levels from one side to the other. Overlap your tiles (I usually go 110 degrees FOV) and increase resolution appropriately. Try increasing GI Prepass Padding even up to 1 if you can afford the render times, maybe test it out at low rez. You could also increase GI quality/sampling settings if you haven't already. As a safeguard (and possibly unnecessary), I always switch off 'Soft clip' and 'Compensate soft clip', which IIRC only affects LDR, but at least you can preview more accurately what the HDR render will look like - the differences in atmospheric glow effects can be quite astounding. Don't forget PTGUI lets you tweak the exposure levels for each tile, which can at least help some of these issues, and clicking on the Auto-exposure doesn't have the same result each click, so you can keep clicking until you're getting closer to an even balance.

[Draigr]

Already done most of what you've said. Applied renders with or without GI. My machine can turn things up a bit.

As I said in my first post. I've already used overlapping tiles. The uploaded zip has overlapping tiles. I'll try some of the others.

PTGUI doesn't recognise the links between the renders at all. Or barely. See for yourself.

[freelancah]

Can you change the file to the EXR ones?

[Draigr]

*Sigh.* Fine.

.exr upload. Enjoy.

http://www.mediafire.com/?wzz27rj322hucee


@JimB. tried your suggestions, didn't work. Seemed to have lessened some of it, but not enough to stop the obvious lines, or allow Hugin (Very much like PTGUI) to do it's job properly.

[JimB]

PTGUI doesn't recognise the links between the renders at all. Or barely. See for yourself.

Don't bother with auto-tiling, just input the camera setting for each tile - enter them manually. To be honest, the sooner TG2 has a panoramic camera for rendering with, the better.

[Kadri]

Could you not cheat a little more , Draigr ?

Instead of only 4 side renders use more to have a smooth dissolve from the sun.
And the renders do not have to be so big horizontally. You can use more renders-steps with narrow renders too make render time faster .
Kind of an animation render...In fact it is an animation sequence of course like the one you use but with more frames.  

Stitching would be easier too for the panorama softwares  with more similar frames to use .
I tried a little bit with Microsoft Ice and it looked good.
You can use videos too  as you know for this probably.
It is the same principle. But i haven't used this feature yet .

How you will get the last step of the upper and lower part i am not sure.
On paper it looks doable but if it is any use to you i don't know.

[Kadri]

A basic test with 41 frames. Curious if this would work with your scene .

Edit: You could then maybe use the resulting image by  cropping it to 4 side views in post and then try to comp it with the upper and lower side.
     
But yes it would be good if this was automatic in TG2

[Matt]

If it's not GI, then I wonder if it is the Acceleration Cache in the cloud layer(s). Try setting those to 'None'.

[FrankB]

I've recently had to render out 30 skyboxes (6 sides each). Really I had no time to figure out the GI problem at the seams, so I created a fill light setup that looked great for the scene. If you ask me this is the way to go until maybe one day TG2 can solve that problem for you. Until then, no GI for skyboxes, use fill lights instead. Granted, it takes some time and test renders to find the ideal fill lights, but it's much faster than trying to solve this GI problem.

This remark just because you mentioned switching off GI earlier: when you decide to switch off GI, then you need to replace it with something else, otherwise all shadows will be black. Use a fill light setup. You'll find one in the file sharing sections or through search.

Regards,
Frank