GI issue with static camera.

Started by bigben, March 07, 2007, 07:40:08 pm

Previous topic - Next topic

bigben

March 07, 2007, 07:40:08 pm Last Edit: March 07, 2007, 07:43:29 pm by bigben
I know there are many know bugs with GI. Not sure if this is one of them so I'll post it anyway.  The attached render has had the gamma turned up to accentuate the detail in the shadows. It's a WIP render of a panorama constructed from 10° tiles. For the most part the image is pretty even except for some glitches in the shadows. (The small strip with objects is another overlay from a separate render)

Volker Harun

I might be wrong - but this is how I understand GI: The calculated dots are the base to level the lighting of this particular render:
The darkest point is set a bit higher than RGB 0-0-0 and the lightest point is to level RGB below 255-255-255.

Errors might occur within one tile due to the density of dots (if the lightest or darkest part did not get caught) and for sure when the camera is turned or moved.

Still - your example shows that there might be another problem, as the shadow parts got really dark.

carloz323

Wow BigBen,

I Love the structure of the rock , especially the one in the detail. Could u enlighten us on how u accomplished that?

Especially the transition from flowing green hills to croppy rocky vertical is very beautiful.

Thanks in advance,

C.

bigben

March 08, 2007, 05:20:32 pm #3 Last Edit: March 08, 2007, 06:36:55 pm by bigben
Quote from: Volker Harun on March 08, 2007, 11:57:22 am
... Errors might occur within one tile due to the density of dots (if the lightest or darkest part did not get caught) and for sure when the camera is turned or moved.

Still - your example shows that there might be another problem, as the shadow parts got really dark.


In this case then, it's probably because there are no light pixels in the image, throwing the balance towards a darker image?? At least I know now that it wasn't just a problem with rendering multiple crops of the same scene. I'll keep this in mind for my next render.

Quote from: carloz323 on March 08, 2007, 01:34:16 pm
Wow BigBen,

I Love the structure of the rock , especially the one in the detail. Could u enlighten us on how u accomplished that?


This project is a combination of my experiments and others' work.
Rocks modifeid from (Personally I find the distortion too much, but I'll tweak that later.):
http://www.designpaths.com/terragen-tutorials/modifying-the-terrain-using-the-redirect-shader/
http://forums.planetside.co.uk/index.php?topic=770.0

Snow:
http://forums.planetside.co.uk/index.php?topic=753.0

Surface transition:
http://forums.planetside.co.uk/index.php?topic=730.0
(Basically an image mask generated by World Machine)

I'm working on an improved plant model (re-surfacing leaves) at the moment while this is rendering.  The penny has just dropped on what some other people were suggesting to me in my earlier experiments and I'm getting very close to a "model" I'm happy with.

Oshyan

I'm unclear on which issue you're pointing out. The tile mismatching is a known problem of GI differences across crops, which I think you're already aware of. The specks could be "holes" in the terrain or several other things. Did you turn off GI and see them disappear, or do you have another reason to suspect GI is involved?

- Oshyan

bigben

Well technically I wasn't cropping a rendered frame. Each tile is a fully rendered image... but the issue behind it isn't new. Just wishful think at the start  ;)