使用VRscans創(chuàng)建布料

我的名字是Luca Veronese，我是一個位于倫敦的小型工作室ScanLAB Projects的首席3D藝術(shù)家。 我們專注于展覽和廣播的3D掃描和點云數(shù)據(jù)可視化。 過去兩年我不得不渲染3D幾何，但我已經(jīng)使用個人項目來學(xué)習(xí)和實現(xiàn)許多不同的工作流程。

My name is Luca Veronese, and I'm Lead 3D Artist at ScanLAB Projects, a small studio based in London. We specialize in 3D scanning and pointcloud data visualization for exhibitions and Broadcasts. I've had to render 3D geometry very rarely in the past two years, but I've used personal projects to learn and implement many different workflows.

Soon after I started using VRscans materials, and saw how incredibly accurate and detailed the shaders are, it became clear to me that I needed a realistic looking geometry to match such high quality. This was the perfect opportunity for me to learn Marvelous Designer, which I'd always wanted to try. My idea was to simulate a piece of fabric falling on top of character, creating a shape with lots of folds, similar to sculptures you might find in a museum.

With this tutorial I will try to guide you through my workflow and show you how to render fabrics in a few simple steps. I'll show you how you can significantly reduce the amount of time spent shading with the right tools and software, and how I rendered within 3ds Max with the power of V-Ray and the VRscans material library.

不久之后，我開始使用VRscans的材料，并看到了如何令人難以置信的準確和詳細的著色器，我變得清楚，我需要一個現(xiàn)實的幾何來匹配這樣的高品質(zhì)。 這是我學(xué)習(xí)Marvelous Designer的絕佳機會，我一直想嘗試。 我的想法是模仿一塊落在角色之上的面料，創(chuàng)造出一個具有很多褶皺的形狀，類似于您在博物館可能會發(fā)現(xiàn)的雕塑。

通過本教程，我將嘗試引導(dǎo)您完成工作流程，并向您展示如何在幾個簡單的步驟中渲染結(jié)構(gòu)。 我將向您展示如何通過正確的工具和軟件顯著減少陰影所花費的時間，以及我如何使用V-Ray和VR掃描資源庫在3ds Max中渲染。

Step 1: Scene set up in 3ds Max

I'd previously created a suit model, and used Marvelous Designer and ZBrush to create the fabric geometry. I imported both into 3ds Max. When I have all my assets in the scene I make sure the texture scale is consistent across all objects. To do this I have use a script called "advanced_uv_normalizer", which copies and pastes the UV map scale from one object to another. This is really helpful, because you can quickly test different materials without too many tiling adjustments.

步驟1：在3ds Max場景設(shè)置

我以前創(chuàng)建了一個西裝模型，并使用Marvelous Designer和ZBrush來創(chuàng)建面料幾何。 我將它們都導(dǎo)入3ds Max。 當(dāng)我擁有現(xiàn)場的所有資產(chǎn)時，我確保所有對象的紋理尺度是一致的。 為此，我使用了一個名為“advanced_uv_normalizer”的腳本，它將UV映射比例從一個對象復(fù)制并粘貼到另一個對象。 這是非常有幫助的，因為您可以快速測試不同的材料，而不需要太多的平鋪調(diào)整。

To render my scene I created a background plane. This is a simple extruded spline, three V-Ray target lights, and a dome light. A dome light with an HDRI texture is usually enough to light a scene, but in this case I wanted more control over the shadows.

With a single subject in the scene, a three light set up is a robust solution that I can quickly adjust to create different moods. This was another key factor in keeping the feedback from the software active. With three lights around the character and very few adjustments, I could simply move my camera around the scene to understand what would work best with my shape, instead of locking the camera angle to a composition that could have required a more complex light set up.

為了渲染我的場景，我創(chuàng)建了一個背景板。 這是一個簡單的擠壓花鍵，三個V-Ray目標(biāo)燈和一個圓頂燈。 具有HDRI紋理的圓頂燈通常足以照亮場景，但在這種情況下，我想要更多地控制陰影。

在場景中的一個主題，三個燈光設(shè)置是一個強大的解決方案，我可以快速調(diào)整以創(chuàng)建不同的效果 。 這是保持軟件反饋的主要因素。 在角色周圍有三個燈光，很少的調(diào)整，我可以簡單地將我的相機移動到現(xiàn)場，來了解什么是最好地形狀，而不是鎖定相機角度的組合，可能需要一個更復(fù)雜的燈光設(shè)置。

Step 2: V-Ray settings

This was the moment when V-Ray for 3ds Max really made a difference, especially version 3.5, which comes heavily optimized and ready to render. I used the default settings, and only adjusted few parameters to better suit my workflow.

First, I deleted the denoiser from the render elements list. I like to keep some noise in my final image - it helps to keep the details sharp. Next I lowered the max ray intensity from 20 to 10, to remove the occasional fireflies. It's not always necessary, but I've found myself having to change the value so many times that I tend to do it by default.

Because I work in IPR (Interactive Production Rendering) mode, it's important to change global illumination to brute force in both the primary and secondary engine. This helps speed up the frame buffer, so it becomes pretty much instant. It is also very important to set the render time from 1 to 0, or the software will stop rendering after 1 minute.

Working in real time is not a new feature for V-Ray, but the real difference of the IPR mode is that I can work in real time with the full power of the production render engine. I can adjust the settings until I'm happy with the result, and then let the render go. At any point I can stop it to save the image, or make changes.

Another important value to consider is the noise threshold, which controls the amount of noise in the final image. It can be adjusted after a few tests depending on the scene, but I tend to work with a default of 0.001.

步驟2：V-Ray設(shè)置

這是3ds Max的v - ray真的做出了改變的時刻，特別是版本3.5的時候，它經(jīng)過了大量優(yōu)化并準備渲染。我使用了默認設(shè)置，只調(diào)整了幾個參數(shù)來更好地適應(yīng)我的工作流程。

首先，我從渲染元素列表中刪除了去噪聲。我喜歡在我的最終形象中保持一些噪音 - 這有助于保持細節(jié)清晰。接下來，我將最大射線強度從20降低到10，以消除偶爾的螢火蟲。這并不總是必要的，但我發(fā)現(xiàn)自己必須多次修改這個值，默認情況下我會這樣做。

因為我在IPR（交互式制作渲染）模式下工作，所以在一級和二級引擎中將全局照明改為暴力是重要的。這有助于加快幀緩沖區(qū)，因此它變得很快。將渲染時間從1設(shè)置為0也是非常重要的，否則軟件將在1分鐘后停止渲染。

實時工作不是V-Ray的新功能，但IPR模式的真正區(qū)別在于我可以在生產(chǎn)渲染引擎的全部功能下實時工作。我可以調(diào)整設(shè)置，直到我對結(jié)果感到滿意，然后去渲染。我可以在任何時候阻止它來保存圖像，或者進行更改。

要考慮的另一個重要價值是噪聲閾值，它控制最終圖像中的噪聲量�？梢愿鶕�(jù)場景進行幾次測試后調(diào)整，但我傾向于默認為0.001。

Step 3: V-Ray frame buffer and physical camera

Before I go into VRscans materials, I would like to show some of the adjustments I've made to the cameras and the V-Ray frame buffer. For the camera I always stick to the same rules that I follow with a regular DSLR, and the physical camera in 3ds Max is perfect for this. I keep the f/stop below 22, which is the maximum aperture that I have in my real lenses. The ISO is between 100 and 400 to help reduce noise, and the shutter type is set to 1/seconds. Depth of field is always enabled, but I might turn it off to speed up the rendering if I need to quickly test something.

Then I enable vignetting, lens distortion and the number of blades in the aperture shape. These are subtle effects - but they are also present in a real camera. I avoid retouching, and I do my colour corrections directly inside the V-Ray frame buffer. I've learnt this trick, and many others, from CGI master Grant Warwick, who I need to thank for all the knowledge he's shared.

I always use LUTs (Look Up Tables), as they help give depth and vibrance to the image. Although they are a great way to achieve many different looks and moods, I like to use always the same two. By using the same LUTs I'm able to keep a certain level of consistency between projects, and I always know what to expect.

Depending on the LUT, I adjust contrast, saturation, and white balance. Generally, I increase both contrast and saturation, and shift the white balance towards higher values to bring back the warmer tones removed by the LUT. I also like to introduce a little bit of blue colour in the shadows, and adjust the lower end of the curve to make them brighter.

I do not change the exposure and highlight burn until I start rendering. I adjust them depending on the type and the amount of lights in the scene. I also adjust bloom and glare in real time.

步驟3：V-Ray幀緩沖器和物理攝像頭

在進入VR掃描資料之前，我想展示一些對攝像機和V-Ray幀緩沖區(qū)的調(diào)整。對于相機，我總是堅持使用與普通數(shù)碼單反相機相同的規(guī)則，而3ds Max中的物理相機是完美的。我將f / stop保持在22以下，這是我在真實鏡頭中的最大光圈。 ISO在100到400之間，以幫助減少噪音，快門類型設(shè)置為1 /秒。景深始終啟用，但如果我需要快速測試某些東西，我可能會關(guān)閉渲染加速渲染。

然后我啟用漸暈，鏡頭變形和刀片數(shù)量的孔徑形狀。這些都是微妙的效果 - 但它們也存在于真實的相機中。我避免修飾，我直接在V-Ray幀緩沖區(qū)內(nèi)進行顏色校正。我從CGI大師格蘭特沃里克學(xué)到了這個方法，我需要感謝他所分享的所有知識。

我總是使用LUT（查找表），因為它們有助于深度和影像的影像。雖然他們是一個偉大的方式來實現(xiàn)許多不同的外表和心情，我喜歡總是使用相同的兩個。通過使用相同的LUT，我可以在項目之間保持一定程度的一致性，我總是知道會有什么期望。

根據(jù)LUT，我調(diào)整對比度，飽和度和白平衡。一般來說，我增加對比度和飽和度，并將白平衡轉(zhuǎn)移到更高的值，以帶回由LUT去除的溫暖的色調(diào)。我也喜歡在陰影中引入一點藍色，并調(diào)整曲線的下端，使其變亮。

我不改變曝光并突出顯示刻錄，直到我開始渲染。我根據(jù)場景中的燈光類型和數(shù)量進行調(diào)整。我也實時調(diào)整綻放和眩光。

Step 4: VRscans material library

VRscans is a library of real life scanned materials. There are already more than 500 materials available and, unlike other material libraries, the quality is impeccable across all shaders.

This is one of the many reasons I'm so excited about it. When shading and texturing it's impossible to rely only on one source, and I often have to combine many of them, and use many different tools, just to create a material or a single texture map. Now I can simply pick one from the Chaos Group website, download it, and apply it to the mesh.

The VRscans material library is having a huge impact in my workflow. For this project, over the course of a weekend, I created 12 still images at high resolution, with so many details that I was able to put together a 9 minute video just by zooming and panning into the images. The following weekend, I tried to create a transparent plastic material of my own and use it on the same fabric mesh. It took me one full day just to create the shader, and eight hours of rendering to have an image that still wasn't what I wanted.

Admittedly, this is a bit of an unfair comparison, as transparent materials takes longer to render, and a more powerful machine or a more experienced artist could have saved some time. But, thanks to VRscans materials, I was able model and render 12 stills and a video in less than two days, compared to more than one day to create a single image that I can only describe as a test render.

步驟4：VR掃描材料庫

VR掃描器是現(xiàn)實生活中的掃描材料庫。已有超過500種材料可用，與其他材料庫不同，所有著色器的質(zhì)量無可挑剔。

這是我非常興奮的原因之一。陰影和紋理化是不可能只依靠一個來源，我經(jīng)常要結(jié)合許多，并使用許多不同的工具，只是為了創(chuàng)建一個材料或一個紋理貼圖�，F(xiàn)在我可以從Chaos Group網(wǎng)站上選擇一個，下載它，并將其應(yīng)用于網(wǎng)格。

VR掃描材料庫對我的工作流程產(chǎn)生了巨大的影響。對于這個項目，在一個周末的過程中，我以高分辨率創(chuàng)建了12個靜態(tài)圖像，具有如此多的細節(jié)，只需縮放和平移圖像即可將9分鐘的視頻放在一起。在下個周末，我試圖創(chuàng)建一個我自己的透明塑膠材料，并在同一個織物網(wǎng)格上使用它。它花了我一整天只是為了創(chuàng)建著色器，八個小時的渲染有一個仍然不是我想要的圖像。

不可否認，這是一個不公平的比較，因為透明材料需要更長的時間來渲染，更強大的機器或更有經(jīng)驗的藝術(shù)家可以節(jié)省一些時間。但是，由于VRscans的材質(zhì)，我可以在不到兩天的時間里模擬和渲染12個靜止畫面和一個視頻，相比之下，創(chuàng)建一個單獨的圖像，我只能形容為一個測試渲染。

Step 5: VRScans material

In a VRayScannedMtl there are only two inputs available. To explain why, I will quote the official document available online:

"The scanned material simply stores information about the way a physical material responds to light at individual points on the surface; it has no notion of components that extend across the surface such as diffuse or reflection qualities, or normal or bump maps. The scanned material is simply a faithful representation of how each point on the object responds to light."

I can't really ask for more, but the team at Chaos Group has taken it further with a series of tools that manipulate the information captured without losing realism.

Thanks to the paintmap and the filtermap, I was able to customize the material colour and tint in the same way I adjust the diffuse color in a regular material. It is possible to select a colour directly in the VRayScannedMtl node, or input a texture, but I found that with fabric materials using a simple paint colour gives better results.

There is also the standard 3ds Max coordinates tab that adjusts tiling and UV mapping projections. When the scale of the mesh is correct and matches real life objects, it is possible to use the "adjust UV tiling to an object" feature. This function finds the correct tiling values for the selected object, and sets the tiling to match the sample size of the scanned material.

The material offers a few more options to adjust the IOR and the bump intensity, but the correct value is set when loading the material. It's better and easier to use a different material, instead of drastically changing, which risks breaking the realism.

There are more advanced tools to optimize the render time and quality, but I'm happy to say that I used the default settings, like almost everywhere else in V-Ray. I can't stress enough how important this was for this project and all the other projects I'm working on - I can focus on my ideas instead of dealing with the technical problems.

步驟5：VRScans材料

在VRayScannedMtl中，只有兩個輸入可用。為了解釋為什么，我會引用在線的官方文件：

“掃描的材料只是存儲關(guān)于物理材料在表面上的各個點對光進行響應(yīng)的信息;它沒有延伸穿過表面的部件的概念，例如漫反射或反射特性，或正�；虬纪官N圖。掃描的材料只是對物體上的每個點如何響應(yīng)光線的忠實表示。

我不能真正要求更多，但Chaos Group的團隊進一步采取了一系列工具來操縱所捕獲的信息而不會失去現(xiàn)實主義。

由于繪制地圖和文件地圖，我可以用同樣的方式來定制材料的顏色和顏色，就像我在普通材料中調(diào)整漫反射的顏色一樣。可以直接在VRayScannedMtl節(jié)點中選擇一個顏色，或者輸入一個紋理，但是我發(fā)現(xiàn)使用簡單的顏料顏色的織物材料效果更好。

還有標(biāo)準的3ds Max坐標(biāo)標(biāo)簽可以調(diào)整平鋪和UV映射投影。當(dāng)網(wǎng)格的比例是正確的并且匹配現(xiàn)實生活中的對象時，可以使用“調(diào)整UV貼圖到對象”功能。此功能可以為所選對象找到正確的平鋪值，并設(shè)置平鋪以匹配掃描材料的??樣本大小。

該材料提供了更多的選項來調(diào)整IOR和凸塊強度，但在加載材料時設(shè)置正確的值。使用不同的材料更好，更容易，而不是徹底改變，這可能會破壞現(xiàn)實主義。

有更多的高級工具來優(yōu)化渲染時間和質(zhì)量，但我很高興地說，我使用默認設(shè)置，就像V-Ray中的其他地方一樣。我無法強調(diào)這個項目和所有其他項目的重要性 - 我可以專注于我的想法，而不是處理技術(shù)問題。

Step 6 Title : Rendering the final stills

This was not the first time I worked with VRscans materials, and I knew that all the models in the scene needed to be as good as possible before I could render the final stills.

At this stage I was still experimenting with different ideas, camera angles and materials. I tried shaders like wood and paints, trying to make the geometry look like a modern sculpture, but the sharp reflections of these materials did not play well with some of the issues left in the mesh. On the other hand, the fabric materials on the other hand gave me even better results with fewer geometry issues.

I would like to tell you all the secrets that went into making this images, but the truth is the shaders simply work. Each one of the final images took about five minutes to set up, and 30 minutes to render.

I cycled through all my cameras every time I was testing a new material, adjusting the light position and intensity to have strong shadows and enough light to show all the details. Not everything I tried worked, but it was nothing like using standard materials. I didn't have to tweak hundreds of parameters simply because I changed my camera position and it felt like I was taking pictures with my camera. I was interacting with the software instead of struggling with it.

第6步標(biāo)題：渲染最后的效果

這不是我第一次使用VRscans材料，而且我知道場景中的所有模型需要盡可能的好，才能渲染最后的劇照。

在這個階段，我還在嘗試不同的想法，相機角度和材料。我嘗試像木材和油漆這樣的著色器，試圖使幾何看起來像一個現(xiàn)代雕塑，但這些材料的尖銳反射在網(wǎng)格中留下的一些問題并沒有很好的發(fā)揮。另一方面，織物材料在幾何問題較少的情況下給了我更好的效果。

我想告訴你制作這些圖像的所有秘密，但事實是，著色器只是工作。每個最終的圖像大約需要五分鐘的時間來建立，并且渲染30分鐘。

我每次測試新材料時都會循環(huán)穿過我的所有相機，調(diào)整光線的位置和強度，使其具有強烈的陰影和足夠的光線來顯示所有的細節(jié)。不是我嘗試過的一切工作，但它并不像使用標(biāo)準材料。我沒有必要調(diào)整數(shù)百個參數(shù)，只因為我改變了我的相機位置，感覺就像我正在用我的相機拍照。我正在與軟件進行互動。

I would like to thank Chaos Group for giving me this opportunity to share my workflow. This is my very first tutorial, so I hope you find it useful! And if you want to give VRscans a test, you can download a fully functional 30-day trial, free of charge.

我想感謝Chaos Group給我這個機會分享我的工作流程。 這是我的第一個教程，所以希望你覺得有用！ 如果您想給VRscans進行測試，您可以免費下載完整功能的30天試用版。