日出日落場(chǎng)景制作——第一部分

在將一盞燈放入3D軟件之前，花一點(diǎn)時(shí)間，觀察現(xiàn)場(chǎng)，思考，想象一下是件好事。這個(gè)任務(wù)非常清楚 - 日落/日出 - 這是“主要指示”。但這并不重要。無論我們必須實(shí)現(xiàn)的照明場(chǎng)景如何，圖像的構(gòu)圖都很重要，而且這也會(huì)影響到燈的位置，強(qiáng)度和顏色。視覺風(fēng)格，藝術(shù)指導(dǎo)也很重要 - 它應(yīng)該看起來真實(shí)，照片真實(shí)，風(fēng)格化嗎？找到一些參考可以提出一些想法，如何實(shí)現(xiàn)我們的任務(wù)�？紤]一下技術(shù)方面的問題也是很好的 - 它會(huì)成為一個(gè)靜止的圖像，還是動(dòng)畫，它是否應(yīng)該渲染得非常快，或者我們可以擁有一些計(jì)算能力？但是現(xiàn)在，當(dāng)電腦速度很快時(shí)，并不總是那么重要。

那么現(xiàn)實(shí)生活中所有理論如何運(yùn)作呢？那么，有兩個(gè)最明顯的（并容易識(shí)別）顯示日落的方式。在第一個(gè)，太陽在相機(jī)后面。建筑物的陰影，特別是在屏幕外的陰影，可以成為現(xiàn)場(chǎng)的一個(gè)非常重要的元素。因?yàn)樵跍嘏�的陽光下有一部分圖像，而在一些涼爽的陰影下，可能有相當(dāng)多的顏色變化（圖01），對(duì)比度不是很高。第二種方法，我們看著太陽 - 有很多明亮的光線，有些東西是有光澤的（因?yàn)樘�陽光的掠過角度），有好的，長(zhǎng)的陰影，整體的對(duì)比度可以相當(dāng)高，但是在那里可能會(huì)有一點(diǎn)顏色變化（圖02）。這兩種方式在心情上有很大的不同 - 當(dāng)然，你可以選擇一個(gè)地方 - 它取決于現(xiàn)場(chǎng)和你想講的故事。

Before placing a single light in a 3d software, it's good to spend a while, looking at the scene, and thinking, imagining a bit. The assignment is pretty clear - sunset/sunrise - that's the 'prime directive'. But that is not all that matters. Composition of the image is important, regardless of the lighting scenario we have to achieve - and that too can influence light placement, strength and color. Visual style, art direction is important as well - is it supposed to look real, photo real, stylized? Finding some reference can suggest few ideas, how to achieve our task. It's also good to think about technical aspects - is it going to be a still image, or is it for animation, should it render really fast, or maybe we have some computing power at our disposal? But nowadays, when the computers are fast, it's not always that important.

So how does all that theory work in real life case? Well, there are two most obvious (and easy to recognize) ways of showing a sunset. In the first one, the sun is behind the camera. The shadows of the buildings, especially off-screen ones, can become a very important element of the scene. Because there are parts of the image in warm sunlight, and some in the cooler shadows, there can be quite a lot of color variation (Fig.01), and the contrast isn't very high. Second approach, we are looking at the sun - there's a lot of bright light, things are shiny (because of the glancing angle of the sun rays), there are nice, long shadows, and the overall contrast can be quite high, but there can be little in a way of color variation (Fig.02). Both ways differ in mood quite a bit - of course, you can choose somewhere in between - it depends on the scene, and on the story you want to tell.

也有相似之處。 在這兩種情況下，太陽是我們的主要（關(guān)鍵）光源。天空扮演著一個(gè)角色，但兩者之間的比例是不同的。使用Vray Sun，Sky系統(tǒng)作為我們的燈光設(shè)置的基礎(chǔ)，至少乍一看。 雖然它應(yīng)該適用于第一種情況，但在第二種情況下可能不夠靈活 - 在特定情況下。 街道盡頭的拱門擋住了地平線（圖03，標(biāo)記為紅色），整個(gè)場(chǎng)景將在陰影中...除非我們嘗試別的東西。

There are similarities, too. In both cases, sun is our main (key) light source. Sky acts as a fill - but the ratio between the two is different. This looks like a great candidate to use Vray Sun，Sky system as a base of our light setup, at least at first glance. While it should work for the first scenario, it may not be flexible enough for the second one - in that particular scene. The arch at the end of the street blocks the horizon, (Fig.03, marked red) and whole scene would be in shadow... unless we try something else.

我們從第一種方法開始。

為了渲染場(chǎng)景，我將3dsmax與Vray一起使用，并開啟了GI。 我經(jīng)常使用Irradiance Map進(jìn)行第一次反彈，使用Brute Force進(jìn)行二次反彈 - 這是默認(rèn)設(shè)置，在大多數(shù)情況下適用于我（圖04 - 預(yù)覽設(shè)置）。 詳細(xì)的設(shè)置，如反彈次數(shù)或輻射圖大小當(dāng)然隨時(shí)間變化 - 預(yù)覽質(zhì)量較差，最終渲染質(zhì)量較高。 對(duì)于靜止圖像，在這種情況下，我嘗試盡可能使用最快（最低）的設(shè)置，同時(shí)仍然得到可接受的結(jié)果。 對(duì)于動(dòng)畫，中等動(dòng)畫設(shè)置通常是安全的，無閃爍的選項(xiàng)。 我還使用全局Ambient Occlusion的一些提示來為圖像的陰影部分添加一些細(xì)節(jié)。

Let's start with the first approach.

To render the scene, I'm using 3dsmax with Vray, with GI turned on. I most often use Irradiance Map for first bounce and Brute Force for the secondary bounces - that is the default setting, which works for me in most cases (Fig.04 - preview setting). Detailed settings, like number of bounces, or Irradiance Map size of course vary over time - low quality for previews, higher for final rendering. For still images, as in this case, I try to use fastest (lowest) setting possible, while still getting acceptable result. For animation, the Medium Animation setting is usually safe, flicker free option. I also use a hint of global Ambient Occlusion to add some detail to shadowed parts of the image.

接下來我做的是將顏色映射設(shè)置為指數(shù)（圖05）。 雖然這可能不是最正確的方法，但它有一些優(yōu)點(diǎn)。 它的工作方式，可以防止過于明亮的“熱點(diǎn)”和過度飽和的顏色過渡。 這也是非常寬容的 - 這是非常困難的圖像，而燈具有一個(gè)非常廣泛的有用的倍增/強(qiáng)度設(shè)置（但范圍往往相當(dāng)高，如512左右，尤其是在霧）。 它也有缺點(diǎn)，使顏色看起來不飽和，降低圖像的對(duì)比度。 我其實(shí)很喜歡，因?yàn)槲铱梢暂p松地將后期制作中的對(duì)比度和飽和度帶回來，而對(duì)于一些場(chǎng)景它恰好適合 - 但是如果你不喜歡它，那就是HSV指數(shù)模式，它可以使色彩更好。 一般來說，我的默認(rèn)主要用途是線性乘法（Linear Multiply），它會(huì)渲染一些額外的通道，比如蒙版。

Next thing I did was setting the Color Mapping to Exponential (Fig.05). While this isn't probably the most physically correct way, it has some advantages. The way it works, it prevents overbright 'hotspots', and oversaturated color transitions. It's also very tolerant - it's really hard to whiteout the image, and the lights have a very wide range of usable multiplier/strength setting (but that range often ends up being pretty high, like 512 or so, especially with the fog on). It has downsides, too, making the colors look desaturated, and decreasing the contrast of the image. I actually like it that way, because I can easily bring back the contrast and saturation in post production, and for some scenes it just fits - but if you don't like it, there's HSV exponential mode, which keeps the colors better. Generally, though, main use I have for default, Linear Multiply, is rendering some additional passes, like masks.

然后，我建立了路面（圖06）。 一個(gè)簡(jiǎn)單的Vray材料，VrayDisplacement修飾符。 我還添加了一些反射到窗口（使用混合材料，VrayMtl的窗口，和黑白面具）。 金屬部件，如欄桿和燈也使用閃亮的反光VrayMtl。

Then, I've set up the road surface (Fig.06). A simple Vray material, VrayDisplacement modifier, and we are good to go. I also added some reflections to the windows (using blend material, VrayMtl for the windows, and a b&w mask). Metal parts, like railings and lamp also use shiny, reflective VrayMtl.

現(xiàn)在是時(shí)候創(chuàng)造太陽。 我們選擇VraySun。 彈出窗口會(huì)出現(xiàn)，詢問在環(huán)境插槽中添加VraySky - 我點(diǎn)擊確定，因?yàn)槲倚枰�它�?接下來，我將VraySky轉(zhuǎn)換為手動(dòng)太陽節(jié)點(diǎn)，并將新創(chuàng)建的VraySun指向太陽節(jié)點(diǎn)（圖7）。 為了獲得更多的控制權(quán)，我使用了天空的兩個(gè)變體 - 一個(gè)用于照明，使用Vray的環(huán)境覆蓋，另一個(gè)是可見的。不同之處在于太陽強(qiáng)度倍增器。

Now it's time to create the sun. Let's choose VraySun. The pop-up will appear, asking about adding VraySky in the Environment slot - I hit OK, since I'll need it. Next I switched VraySky to manual sun node, and pointed the newly created VraySun as the sun node (Fig.07). To have a bit more control, I used two variants of the sky - one for lighting, using Vray's environment override, and one to be visible. The difference is in the sun intensity multiplier.

要定位太陽，最好在視口中顯示陰影（圖08）。 這樣，我可以實(shí)時(shí)看到陰影，找到一個(gè)很好的作品是非�？斓�......但是等等，沒有什么東西可以在我們的街道上投下陰影。 很容易修復(fù) - 只畫幾個(gè)天際線形的角形樣條，然后擠壓一下，然后大致放在街道另一邊，然后從那里調(diào)整（圖9）。 在這里我選擇了在圖像中有一個(gè)很好的光線路徑，兩邊都是黑色的形狀。

To position the sun, it's good to display shadows in the viewport (Fig.08). That way I can see the shadows in real-time, and finding a nice composition is really fast... but wait, there's nothing that could cast shadows on our street. It's easy to fix - just draw few skyline-shaped, angular splines, and extrude them a bit, then place roughly where the other side of the street would be, and tweak from there (Fig.09). Here I chose the to have a nice, lit path into the image, and dark shapes on both sides.

在渲染任何東西之前，我創(chuàng)建了VRayPhysicalCamera，所以我可以更直觀地控制場(chǎng)景的亮度（因?yàn)槲矣幸恍�攝影經(jīng)驗(yàn)）。 圖（圖10）上的設(shè)置需要一些試驗(yàn)和錯(cuò)誤才能使它們正確 - 一般情況下，如果場(chǎng)景或多或少地以現(xiàn)實(shí)世界的規(guī)模構(gòu)建，那么如果我們要拍攝該場(chǎng)景的照片 在現(xiàn)實(shí)生活中，是一個(gè)很好的起點(diǎn)。 漸暈選項(xiàng)在這里非常有用，使圖像的邊角變暗，并將觀眾的注意力集中在圖像的中心部分。 我也調(diào)整了太陽的亮度和大小，以獲得好的，柔和的陰影。

Before rendering anything, I created VRayPhysicalCamera, so I could control the brightness of the scene in more intuitive way (as I have a bit of photographic experience). The settings pictured on (Fig.10) took some trial and error to get them right - generally, if the scene is more-or less build in real world scale, the settings that would work if we were to take a photo of that scene in real life, are a good starting point. The Vignetting option is quite useful here, darkening the corners of the image, and focusing the viewers' attention at the central part of the image. I also adjusted the sun brightness, and size, to get nice, soft shadows.

讓我們看看我們有什么（圖11）。 不是那么糟糕，但可能會(huì)更好一些 - 我希望陰影中有更多的藍(lán)色，還有更多的光線在圖像的中間部分。 我在場(chǎng)景的前面添加了一個(gè)藍(lán)色的Vray Light（圖12）。

Let's see what we've got (Fig.11). Not that bad, but could be better - I'd like some more blue in the shadows, and some more light in the central part of the image. I added a big blueish Vray Light above and to the front of the scene (Fig.12).

這樣會(huì)產(chǎn)生更多的色彩變化，而且看起來更像日出，但是很容易回到夕陽的領(lǐng)域，后期制作幾乎沒有任何調(diào)整。 另一個(gè)沿著街道較小的光線（圖13）點(diǎn)亮了拱壁，這對(duì)我的口味來說太暗了。

This gives more color variation, and, as it is, looks more like a sunrise, - but it's easy to go back into sunset territory, with few tweaks in post-production. Another, smaller light further along the street (Fig.13) lights up the arch wall, which was bit too dark for my taste.

我還在弧后加了一個(gè)小燈，所以圖像中間沒有大的平坦黑點(diǎn)（圖14）。

現(xiàn)在，讓我們把圖像帶入Photoshop，看看我們可以用它做些什么。 使用曲線調(diào)整圖層，我將大部分的藍(lán)/紫色從陰影中取出，使整個(gè)圖像變得更溫暖（圖15），漸暈，有些發(fā)光，最終結(jié)果如下（圖16）。 總而言之，這不是太難，是嗎？

I've also added a small light behind the arch, so there's no big flat dark spot in the center of the image (Fig.14).

Now, let's take the image into Photoshop, and see what we can do with it. Using Curves Adjustment Layer, I brought down most of the blue/violet from the shadows, giving the whole image a warmer tone (Fig.15), played with vignetting, and some glows, and here's the final result: (Fig.16). All in all, this wasn't too hard, was it?