What Does The 64-Bit Render Target Do?

[Elf Juices]

Does anyone know what this setting does? It has it disabled by default for me.

[Gubernaut]

Yea I'm wondering too could some smarty pants get on this?

[Elf Juices]

It's kinda weird, because Skyrim's launcher has it automatically disabled when it auto-detects my system, but geforce experience says is't optimal to have on.

[Echoside7]

https://forums.nexusmods.com/index.php?/topic/4983100-what-is-this-64-bit-render-targets-option/

Second post has link with all the tech babble... Looked a lot like a mix between Ancient Sumerian and binary to me though.

[Elf Juices]

Interesting, thanks for the link echo. They mentioned colors looking a little better in terms of saturation. I'll enable it and see if I can spot a difference.

[Gubernaut]

Best thing would be to get some comparison screen shots (taken from the exact same position)

[Elf Juices]

Emton の投稿を引用：

Best thing would be to get some comparison screen shots (taken from the exact same position)

Good idea, I'll definitely do that in a little bit.

[Gubernaut]

Here I took a set of screen shots

http://steamcommunity.com/sharedfiles/filedetails/?id=788798488 off
http://steamcommunity.com/sharedfiles/filedetails/?id=788799938 ON

I compared the histograms in photoshop and can see there seems to be more pixel information with 64 bit render targets on. It's hard to see but I think it gives some better contrast maybe a little more "HDR" effect. You can see it some in the distant mountain range. But I think it costs a few frames. These are jpg pictures though and pretty crappy some lossless pictures would be better to compare...

[Gubernaut]

Here's those pictures if anyway want to compare them

[Elf Juices]

You know what I noticed was that looking up at the sky, without the 64bit option on, there was all kinds of banding. This was very noticable when looking right at the sun with the blue sky in the background. With the 64 bit option on, it completely eliminated the banding. I took screenshots of this, but for some reason they don't reflect what is seen in game at all. You might just want to try it for yourself if you are curious. For me, I noticed a big difference.

Thanks for sharing your screen shots, and the info about the histogram in photoshop is definitely very interesting. I think you may be right about the contrast and HDR like effect.

[Istapp]

Ya.

"64-bit Render Targets: Eliminates color banding in brightly-lit scenes by using high precision render targets."

Not sure what render targets mean exactly though, but that's a good enough explanation for me. That's one of the things Geforce Experience has going for it btw. Gives you a little technical explanation about the game.

[Belanos]

SolarShadow の投稿を引用：

It has it disabled by default for me.

It's probably an Ultra thing as it's enabled in my file.

[Ancient]

The primary difference is all about precision.

32-bit has a smaller precison limit where a result is truncated to a specific decimal place to fit the byte limit of 32-bit. A Binary32 (single-precison floating-point) number occupies 4 bytes (32-bits) in memory, while Binary64 (double-precision floating-point) numbers occupy 8 bytes (64-bit) in memory. 64-bit is not technically more efficient it's the other way around. The extra precision is not free but rather costs double the computational and memory overhead of 32-bit. You can store two 32-bit FP numbers in the same space as a single 64-bit FP number: 8 bytes.

Quick examples (don't fault me on accuracy as I did not count decimal places here):

binary32 example: 1.067346282783 (647592783763 < 64-bit data which is truncated and thus considerable precision is lost under 32-bit)

binary64 example: 1.067346282783647592783763 ( < 64-bit offers double the precision of 32-bit, significantly increasing precision of a given calculation)

The actual result may have been more like 1.067346282783647592783763827164937357398092746352~ or perceptibly larger to an almost infinite degree. However, nearly all floating-point calculations must be truncated to some specific byte limit to fit a specific format. The actual degree to which the decimal points are left untruncated is considered the precision of the format.

In graphics applications, the benefits of 32-bit vs 64-bit are typically similar to those seen in raster calculation formats such as 8-bit vs 16-bit vs 24-bit vs 32-bit vs 48-bit: higher bit formats offer increased precision and result in a reduction in visible banding and an overall increase in smoothness (dither) across color spectrums by increasing the potential targets in the spectrum exponentially.

The difference that this kind of expontnential shift to more color targets actually makes is most easily observed by comparing 8-bit color palettes (256 colors)[cdn.cambridgeincolour.com] to 16-bit color palettes (65536 colors)[cdn.cambridgeincolour.com].

[gyuuula]

"64 bit format. This has good precision, and also leaves us with another channel were we can store an extra attribute."
from
http://www.catalinzima.com/xna/tutorials/deferred-rendering-in-xna/creating-the-g-buffer/

The important part isn't precision, but "the extra attribute", which means PARALLAX TEXTURES.
https://www.google.hu/search?q=parallax+textures&num=50&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi18aLInZnRAhVHVBQKHZHwChQQ_AUICCgB&biw=1366&bih=670

If you have a proper texture pack installed (base textures don't have parallax information) and a good video card, enable 64 bit rendering. Otherwise, it doesn't makes much sense.

[Elf Juices]

It helps because with 32 bit all the gradients have terrible banding. 64 solves all that. That's the only difference I've noticed

[PaleHorse.Rider]

I'm probably late here [in my defense I just recently got the game]
64 bit render targets simply aims to render illumination sources in 64 bit, and tries to minimize color banding in brightly lit scenes.
This is the simplest way I could put it.