Tile/bucket differences

Started by Kevin F, November 15, 2009, 07:42:06 am

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Kevin F

Here's an image I've just finished that failed to render one tile on the bottom row. I re-rendered this area with "detail in crop region" and "ray detail region padding" set to 1, and have patched the new area into the original. This gave much the same result as with padding set to 0. Why is there such a big difference in colour between renders? The green reflections are completely different.
and what if anything do you suggest I do to improve this?

Henry Blewer

If detail in crop region was not enabled in the original render, whether or not a crop was used, the color is calculated differently. At least that's what I think happens from other threads I have read.
http://flickr.com/photos/njeneb/
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Kevin F

Quote from: njeneb on November 15, 2009, 08:44:48 am
If detail in crop region was not enabled in the original render, whether or not a crop was used, the color is calculated differently. At least that's what I think happens from other threads I have read.


It was in the original.

Kevin F

Quote from: Kevin F on November 15, 2009, 11:47:43 am
Quote from: njeneb on November 15, 2009, 08:44:48 am
If detail in crop region was not enabled in the original render, whether or not a crop was used, the color is calculated differently. At least that's what I think happens from other threads I have read.


It was enabled in the original.

Henry Blewer

It's something Jo, Oshyan, or Matt should answer. That way, you would get the correct answer, instead of my educated guess. Sorry if I was not much help.
http://flickr.com/photos/njeneb/
Forget Tuesday; It's just Monday spelled with a T

Kevin F

Quote from: njeneb on November 15, 2009, 03:00:45 pm
It's something Jo, Oshyan, or Matt should answer. That way, you would get the correct answer, instead of my educated guess. Sorry if I was not much help.

No prob, thank for responding.

Kadri

How much bigger did you render the crop Kevin F ? Just curious.
Did you try a more  bigger crop ones more ?

Kadri.

Kevin F

Quote from: Kadri on November 15, 2009, 04:11:37 pm
How much bigger did you render the crop Kevin F ? Just curious.
Did you try a more  bigger crop ones more ?

Kadri.


Here's the original:

Kadri

November 15, 2009, 05:39:12 pm #8 Last Edit: November 15, 2009, 05:43:40 pm by Kadri
I would try a crop something like this. If there are problems you can not correct in post i would try a more  bigger one too.
But maybe it is with your settings. This is not a problem i can help.

Edit: A last resort would be rendering the water  section below and comp in post.

Kadri.

Oshyan

Ok, this is a consistently confusing issue, and unfortunately I am not immune to the confusion! I will try to state how I understand it, and hopefully Matt can correct me as it will almost certainly not be 100% accurate. ;)

Here's the thing: As I understand it, Ray Detail Region does NOT affect GI! From the results I've seen, it seems to have consistently not addressed GI-related issues like this. And my recollection from multiple posts from Matt also indicates this, though I'm not sure it has ever been crystal clear.

I know that the feature was originally introduced to address *shadow* issues with off-screen geometry (perhaps among other issues, e.g. reflections from off-screen geometry). It would also help with shadows from out-of-crop geometry with the right settings, of course. So this was its purpose. But that does not say anything about GI...

I think what happened is that, because it helped with off-screen geometry shadows, people assumed it did the same for GI (for everything basically). But again I don't think that's actually the case. That being said it would be good if it did do that. I'll have to have Matt confirm/deny/clarify all this. ;D

- Oshyan

Kevin F

Thanks Oshyan, but regardless of Ray Detail region and GI issues not helping, do you know of any other ways around this issue. Why are there such big differences between renders? Has this been fixed for 2.1?

Oshyan

I don't know any really good, reliable ways around the issue aside from just not using GI. Although the more I look at your image, I'm not sure it's not partly reflection being missed as well, which ought to have been helped by the crop detail region I *think*.

The reasons why there are big differences have been discussed before. Basically the renderer has to take the entire scene into account for a "perfect" and 100% consistent GI solution. But doing so would make render times skyrocket (multiply your render time by 360 degrees of view in the scene and you have an idea), so the GI calculations usually limit to near the view of your camera, which generally produced an accurate, "good enough" result. In crop renders, the GI region is limited to the crop regions, so you have an even more limited area from which the GI samples are drawn, and the accuracy is correspondingly lower. That's why you get differences.

As far as I'm aware there have been no fixes to this for 2.1 unfortunately.

- Oshyan

Kevin F


buzzzzz1

I have had this crop up as well, pardon the pun.  ;)  The only solution I have found is to layer the crop section into the main image with photoshop or whatever you use and adjust the brightness/contrast and/or colors to match the larger render or the smaller crop, whichever you are after. It's actually rather easy.
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domdib

Oshyan, I thought Matt had confirmed that setting the Ray detail region to "in camera" helped? Also, as I understood it, increasing GI blur may also help?

One other thing that sometimes helps is exporting different crops as EXR, and then exposing them slightly differently, e.g. 0 and 0.1.