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What would be a good way to make a 3D scene look "like" a dark night, without being so dark on the monitor that it's hard to see stuff (especially when playing in a brightly lit room).

I've been experimenting with making the light bluish in nature, and having a fairly dark ambient component with a brighter diffuse component, but I find the result either a bit lack-luster or still too dark, depending on the exact parameters.

Are there any good examples to study?

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  • \$\begingroup\$ For humans, low-light visibility is achieved by a combination of widening the iris to allow more light in (more sensitive to very-dark) plus a chemical response that adjusts the perceived "contrast" levels (less difference between very-dark and not-as-dark). \$\endgroup\$ – Jon Apr 24 '15 at 3:05
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    \$\begingroup\$ This could be simulated by overall de-saturation of the color buffer, averaging colors toward something like Color::Silver(moon colored), while also applying Silver as a modest ambient. Where you would ordinarily use NDL to adjust the output color, you might, instead, use it as the basis for de-saturation. Areas that would be "well-lit" during the day are, instead, "well-colored" at night. \$\endgroup\$ – Jon Apr 24 '15 at 3:06
  • \$\begingroup\$ Hmm, that's quite an interesting though, indeed. I'm not sure how to fit it into my engine at the moment, given that the output of my day-night cycle is a set of ambient-diffuse-specular colors, but I'll see if I can't think of some way. \$\endgroup\$ – Dolda2000 Apr 24 '15 at 3:09
  • \$\begingroup\$ The sampled texture colors and NDL will still be used. Day or night, NDL for your "lit" colors but, during the night-cycle, also de-saturate the NDL color based on the same dot. Your scene will still be NDL as usual, except that badly-lit pixels will also de-saturate toward Silver/moonlit instead of "black"/transparent/unlit. Well-lit pixels might be only 25%-50% desaturated. \$\endgroup\$ – Jon Apr 24 '15 at 3:14
  • \$\begingroup\$ For anyone else who's wondering: "NDL" which is mentioned here in the comments, means "neutral daylight". At least I think so. \$\endgroup\$ – Stefan Monov Oct 2 '16 at 17:16
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This is one case where it's useful to steal ideas from Hollywood, who have been doing this for decades.

typical hollywood night scene

Typical hollywood night scene, also related question from Movies.SE

The picture above was filmed during the night time, but it's not actually a dark picture. Notice how the actors' faces are very well lit, although the sky is pitch black and the road is very bright (which you wouldn't normally expect). Studying similar shots will give you some clues to how you can fake a night scene while still allowing your viewers/players to actually see.

Tint things blue/purple

This one's easy to guess; since sunlight is usually yellow, the spectral opposite of that happens to be bluish/purplish. That is, take neutral white light, remove yellow, and you end up with a blue/purple colour.

Desaturate colours

Since our night vision uses rods which can't see colour, reducing saturation emulates this effect.

Increase contrast

Increasing contrast has the effect of making bright things brighter and dark things darker. This simulates reality where, in dark conditions, bright things like artificial lights look much brighter in comparison, whereas we lose the ability to see dark details.

Darken skies

And also darken things that are typically bright during the day but dark during the night. This actually goes a long way towards the illusion and seems less "artificial" than tricks like making your scene blue. In the old days, with black/white cameras, they took advantage of this by filming during the day with a red filter over the lens, which conveniently darkens the blue sky but little else.

day and night sakura tree

Hey look it's night time. - Bret Victor - Inventing on Principle

The corollary of that is to brighten things that are dark during the day but bright at night. Think artificial light sources like flashlights, campfires, computer screens. Exaggerate their brightness.

Add light sources from "unnatural" angles

If you don't have the luxury of actual light sources (like full moon, or streetlights) in your night scene, you still need to add some light so viewers/players can see, but make them cast light in funny angles so they aren't associated with the sun and break the illusion. Daylight typically comes from above at a slight angle, and this trope extends everywhere, even in UI where "3D" buttons are typically brighter at the top and left edges, and drop shadows extend down and right. For night time, reverse those angles. Have lights illuminating from below, or behind your subjects. Behind is particularly neat as it shows silhouettes but leaves features undefined, mimicking the ominous dark.

typical night scene

Some night scene; note the light angles and the well-outlined hat and afro

A lot of these tricks come from a filmmaking technique known as "Day for night", which is where a low-budget film will shoot night scenes during the day but use a number of filming tricks and editing to make it look like night. The relevant tricks I've already mentioned above but you can read on here: http://www.videomaker.com/article/10368-shooting-day-for-night

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    \$\begingroup\$ Regarding the pictures you cited as examples, while it might not be the case in those instances, most "night scenes" are actually shot in broad daylight, and either altered in post-processing or live using lens filters. The reason behind this is mostly monetary: it costs way more to hire crew and actors to film at night, plus if you are actually using film, it costs a lot to develop film that could end up being too dark or grainy, so most productions take no risks and simply shoot during the day. Plus, the alternatives give good enough results. \$\endgroup\$ – sleblanc Apr 24 '15 at 22:07
  • \$\begingroup\$ @OP: this points out the fact that you can "fake" dark scenes by replicating cinema techniques in 3D graphics. Boost the contrast, shift the hue to traditionally "dark" colors (blue, purple), lower the dynamic range, and as congusbongus said, put shadows at unusual angles. Make sure the sky is pitch dark, save for some artistic license, and you will get results. \$\endgroup\$ – sleblanc Apr 24 '15 at 22:13
  • \$\begingroup\$ @sebleblanc that may have been true in the past, but in recent decades the vast majority of night scenes are actually filmed at night. Not to say they must be; just that day-for-night has taken a back seat recently. \$\endgroup\$ – mhlester Apr 25 '15 at 5:38
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    \$\begingroup\$ Great answer. One addition: key to fill ratios are different at night. During the day the sun illuminates more sky, which casts its own light filling in shadows. At night there's none of that so the lighting is much more stark. Partially addressed in the paragraph about contrast, but perhaps worth fleshing out. \$\endgroup\$ – mhlester Apr 25 '15 at 5:41

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