render uncertainty

[EmDee1]

I've rendered two images of exactly the same tgd file; only changed the image width and -height in the Full Render settings: one image 320x240, the other: 640x480 pixels. Both renders look completely different in colour, texturing and lighting. eh...
Attached I sent the concerning tgd-files, the WorldMachine Heightfield I used and the two rendered images. Checked and rechecked the tgd-files, but they look exactly the same. Maybe I overlooked something...

[rcallicotte]

I've seen this before.  In an another situation, which is closely related to this, I rendered an entire picture of 2400X1440 and then went back to render only smaller cropped areas.  Interestingly, the cropped areas were more defined, tighter in color, and seemingly denser as a whole than the larger 2400X1440 picture.  I believe I read once that Matt explained this as having to do with how GI is calculated...or it might have had something to do with the scope of the render. 

I'm sure someone else might be able to explain this better.

[nikita]

For GI calculations, TG2 doesn't consider areas outside the actual render quad. So when you use crop, the lighting situation will be different then if you render the whole image.

I guess EmDee1s problem is similar and that the accuracy of GI rises with image size.

[EmDee1]

Thanks Calico and Nikita for your replies. Still hope there will be more said about the subject...
At this very moment I feel a bit confused and frustrated, feeling that this amazing TG2 Landscape render-engine (still the best in its domain in my opinion), leaves me with a great uncertainty. Why use crop renders, why use smaller renders as a preview, as the final render result can differ considerable from what one might expect?

[rcallicotte]

I was able to manipulate my crop renders with Photoshop to readily fit within the original scene.

[Oshyan]

TG2 *does* consider areas outside the crop/render area for GI, but it has to do so at a lower detail level than the main render for reasons of time. This can result in inconstencies like those described here. The GI system will be improved over time, but for now it may be best in these situations to simply use a fill light setup such as the one provided in the File Sharing area here: http://forums.planetside.co.uk/index.php?topic=580.0

GI accuracy is also relative to detail level (hence the setting name "GI Relative Detail"). So if you have this set to 2 and detail at 0.5, if you then increase detail to 1.0 and leave Relative Detail at 2, the lighting can change because the GI detail has actually increased with the overall increase in render detail. Again these consistency issues will be worked on but inevitably with any GI solution you are going to see differences at varying levels of detail. If the inconsistency is a significant issue a well-tuned fill light setup ought to give you reasonably similar results with more consistent output.

- Oshyan

[EmDee1]

Thanks; I'm gonna study the suggested fill-light-setup topic.

[EmDee1]

Feel a bit stupid , but I cannot get the fill-lights-setup working...
I deleted my existing lighting nodes, turned off GI (GI rel detail to 0 and GI sample quality to 0, right??),then inserted the fill lights.tgc. In my preview window I can see the changes when I adjust color and strenght, but when I render: just a grey landscape, what ever I try. I múst be doing something wrong, tried the last two hours to find out, without result...

[rcallicotte]

Which fill-lights?  If you mean Oshyan's, they should just work.  Same with Moodflows, but Moodflows can work with the scene as is without deleting anything.  Of course, Oshyan's can too, but his has a sun light included, while Moodflows is multiple suns.

[EmDee1]

I used Oshyan's fill lights setup. Preview window shows it works, but why not with a Full Render ...

[rcallicotte]

Post the TGD if you can.  Let's look at it.  I have about a half-hour I can look at this.

[EmDee1]

Maybe my render settings are wrong? Forgot something?
Detail: 0.5
AA: 5
GI detail: 0
GI sample: 0
GI surf details: unchecked
Attached two pictures: 1e with modest Fill Light strenght setting at 0.5, 2e with overexposed Fill Light strength setting of 3...

[rcallicotte]

Since I can't see the TGD, I don't know.  Have you tried rendering from 1K above the surface to make sure you aren't behind or underneath something?

[EmDee1]

tgd file attached, thanks Calico...

[EmDee1]

Sorry, the tgd-file I send you was not the latest one; include that one now...