Profit from high GI settings

[PorcupineFloyd]

I was wondering if there is any real benefit from using high GI settings.

Isn't 1/1 with supersample really enough? Or is there any difference at all between 2/2 and 3/3 for example? And what about 5/5 or 7/7?

Perhaps someone did some testing with example pictures?

[Volker Harun]

I did some test renders. And indeed the supersample is a very nice addition.
I - for me personally - see no advantage beyond activated supersample and a GI-setting 2/3.
Due to rendertime issues I mostly use supersample with 1/3.

I must add that any of my scenes has a lot diffuse light - at least because of an overcast (high cirrus, depth 50-80, coverage of 1-2 and lowered cloud colours). You'll need to increase the camera's exposure for it and get lit up shadows.

[PorcupineFloyd]

Interesting point.

So - you prefer not to increase relative detail over 1 but increase sample quality instead?

What does the relative detail do at all? Sample quality corresponds at amount of samples being rendered but what about relative detail?

[rcallicotte]

This might give some insight -

"Improvements to Global Illumination and render prepass:
    Improved prepass sample distribution.
    Option to supersample the prepass (in render node settings). This takes more image samples in the prepass without increasing the total number of GI light samples. This provides a better coverage of GI on small parts or edges of objects and clouds, with a smaller increase in render times than a similar increase in GI relative detail.
    GI blur radius can be changed by the user (in render node settings)." - Matt


http://forums.planetside.co.uk/index.php?topic=1877.msg18288#msg18288

http://forums.planetside.co.uk/index.php?topic=3496.msg35992#msg35992


Interesting addendum - http://forums.planetside.co.uk/index.php?topic=1475.0 and http://forums.planetside.co.uk/index.php?topic=1884.msg18381#msg18381

[PorcupineFloyd]

Thanks for the links. It makes things pretty clear now

[rcallicotte]

For me, too.  This has been a very helpful thread.

[Matt]

There are some scenes where 1/1 gives completely inadequate results. The GI may be splotchy, lacking in contrast, or it just looks wrong. The settings are there to allow you get better results in those situations, but it's difficult to generalise about what sorts of benefits you will get from using higher GI settings because it is different for every scene. It is often worth spending some time testing different settings on whatever scene you are working on.

Matt

[PorcupineFloyd]

I think that I have an image-proof of what you're talking about, Matt.

I recall that one of my first TG2 renders had 1/1 GI - http://porcupinefloyd.deviantart.com/art/Green-is-the-Colour-95992297

You'll have to click "Download" for full sized picture to clearly see lack of illumination detail on trees in some parts - specifically this "absolutely dark line of trees" in the lower center part of the image.