沙漠賽車——第2部分

在本教程中，我將通過紋理和合成我們未來的沙漠賽車從上個月的問題建模教程。 特別是，我們將研究如何使用Maxwell Render的材料編輯器從珠光漆，碳纖維和金屬制造各種材料。 我們還將通過使用Maxwell海洋工具創(chuàng)建巖石和樹木的前景，遠(yuǎn)程背景，使用麥克斯韋霧霧發(fā)射器創(chuàng)建深度的過程，最終我們將使用HDR照明將所有這些元素放在一起。

In this tutorial I will be following on from the modeling tutorial in last month's issue by texturing and compositing our futuristic desert racer. In particular we will be looking at how to create a variety of materials from pearlescent paint, carbon fiber and metallics using Maxwell Render's Material Editor. We will also go through the process of creating a foreground with rocks and trees, a distant background using the Maxwell Ocean tool, creating depth with the Maxwell Fog Emitter, and finally we will bring all of these elements together using HDR lighting.

Step 01: Base landscape

In Maxwell Render, the first step we need to take is to create a large expanse of background desert for our scene to take place. By selecting the Maxwell shelf we can access the new Maxwell Ocean tool. Simply click on this to generate an ocean plane. In order for the fog to work effectively, I resize the ocean to be very large in the scene at a 45-degree angle to our vehicle. In order to make the ocean look more like a sloping desert, we need to adjust the settings, and for the fog to dissipate naturally a low setting of 0.3 set to 'Constant' should give the effect we need.

步驟01：基礎(chǔ)景觀

在Maxwell Render中，我們需要采取的第一步是創(chuàng)建一個大的背景沙漠，為我們的場景發(fā)生。 通過選擇Maxwell架，我們可以訪問新的Maxwell Ocean工具。 只需點(diǎn)擊這個生成海洋飛機(jī)。 為了使霧有效地工作，我調(diào)整海洋的大小在場景中與我們的車輛成45度角。 為了使海洋看起來更像一個傾斜的沙漠，我們需要調(diào)整設(shè)置，為了霧自然消散0.3的低設(shè)置為“常量”應(yīng)該給我們需要的效果。

Step 02: Foreground

As the foreground is closest to the camera we need to have much better detail. So first we need to create a polygon plane and add edge loops in line with the wheel direction, then extrude downward a small amount to create a natural-looking wheel groove in the ground. In order for the sand to match up with this, we must make and export a UV map for Photoshop. In Photoshop, place a tileable sand texture (see downloadable resources) and paint out the sand pattern as if it's been driven across. We'll apply this texture later in the tutorial.

步驟02：前景

由于前景最接近相機(jī)，我們需要有更好的細(xì)節(jié)。 首先，我們需要創(chuàng)建一個多邊形平面，并添加與車輪方向一致的邊緣環(huán)，然后向下擠壓少量，以在地面中創(chuàng)建一個自然的輪槽。 為了使沙子與此匹配，我們必須在Photoshop制作和導(dǎo)出UV地圖。 在Photoshop中，放置一個tileable沙子紋理（見可下載的資源），并畫出砂圖案，如果它被驅(qū)動。 我們將在本教程的后面應(yīng)用這個紋理。

Step 03: Making rocks using photogrammetry

Now I will demonstrate the process of making simple and effective rocks using 123D Catch.123D Catch is a free online resource from Autodesk where you can upload images of any object and automatically transform it into a usable 3D object!

The first step you need to take is to bring your dog for a walk and find some lovely stones. It's best to use stones that look like miniature rocks, so pick ones with rough details and crevices. Go to 123D Catch and follow the simple instructions.

After you upload the photos and export your model from 123D Catch, import it back into Maya and delete all of the unnecessary geometry. By pressing '6', you can preview the texture. That's it - instant rocks!

步驟03：使用攝影測量法制作巖石

現(xiàn)在，我將演示使用123D Catch.123D制作簡單有效的巖石的過程。Catch是Autodesk的免費(fèi)在線資源，您可以上傳任何對象的圖像，并自動將其轉(zhuǎn)換為可用的3D對象！

你需要采取的第一步是找到一些可愛的石頭。 最好使用看起來像微型巖石的石頭，所以選擇粗糙的細(xì)節(jié)和裂縫。 轉(zhuǎn)到123D抓住并按照簡單的說明。

上傳照片并從123D Catch導(dǎo)出模型后，將其導(dǎo)入Maya并刪除所有不必要的幾何體。 按'6'，可以預(yù)覽紋理。 就是這樣 - 即時巖石！

Step 04: Image-based lighting (IBL)

In the project files for this tutorial you will be able to download this outstanding extra-large HDR image, supplied to us exclusively by doschdesign.com. Dosch Design supply artists with an array of products including beautiful high-quality HDR images, so I am very grateful to Sebastian Dosch for letting us use this image.

To access this image we need to enable Image Based Environment in the Maxwell Render settings window. I find an Offset U value of 25 and an Offset V value of 5 work nicely to get the most from this HDRi. Of course, this is a matter of personal taste.

步驟04：基于圖像的照明（IBL）

在本教程的項目文件中，您將能夠下載此出色的超大HDR圖像，由doschdesign.com獨(dú)家提供給我們。 Dosch Design為藝術(shù)家提供了一系列的產(chǎn)品，包括美麗的高品質(zhì)HDR圖像，所以我非常感謝Sebastian Dosch讓我們使用這個圖像。

要訪問此圖像，我們需要在Maxwell Render設(shè)置窗口中啟用基于圖像的環(huán)境。 我發(fā)現(xiàn)偏移U值為25和偏移V值為5可以很好地利用這個HDRi。 當(dāng)然，這是個人品味的問題。

Step 05: Lighting alternatives

In this step we will take a look at some lighting alternatives. If you do not have access to the Dosch HDR image you can find some nice free alternatives online. One such place is HDRLabs (hdrlabs.com) which offers a wide range of free quality HDR images.

Another great alternative is to use the built-in Sky Dome in Maxwell Render. The advantage of using the Maxwell Sky is that you have a huge amount of control over the lighting itself, such as time of day, atmospherics and location. This can be accessed in the Render settings under the Maxwell tab.

步驟05：照明替代品

在這一步，我們將看看一些照明替代品。 如果你沒有訪問Dosch HDR圖像，你可以找到一些很好的免費(fèi)替代品在線。 一個這樣的地方是HDRLabs（hdrlabs.com），它提供了各種各樣的免費(fèi)質(zhì)量HDR圖像。

另一個偉大的選擇是使用內(nèi)置的天空穹頂在麥克斯韋渲染。 使用麥克斯韋天空的優(yōu)點(diǎn)是，你對照明本身有很大的控制權(quán)，例如時間，大氣和位置。 可以在Maxwell選項卡下的Render設(shè)置中訪問。

Step 06: Adding foliage

In this step we will use a free sample from Xfrog to populate our scene with foliage. It's time to add some trees into our scene. For this there's no better place than Xfrog. As this is a desert environment, I've chosen the Queen Palm set which you can download for free from the Xfrog website (xfrog.com/product/TR19.html). You can choose to download the models in multiple formats, but Maxwell is not one of those formats, so I will supply the Maxwell Materials for this tree in the downloadable project files. Next, place the trees into the scene to fill any spaces in the composition and apply the materials as labeled.

步驟06：添加樹葉

在這一步中，我們將使用Xfrog的一個免費(fèi)樣本來填充我們的場景中的樹葉。 是時候給我們的場景添加一些樹。 對于這一點(diǎn)沒有比Xfrog更好的地方。 由于這是一個沙漠環(huán)境，我選擇了皇后棕櫚集，你可以從Xfrog網(wǎng)站（xfrog.com/product/TR19.html）免費(fèi)下載。 您可以選擇以多種格式下載模型，但Maxwell不是這些格式之一，因此我將在可下載的項目文件中為此樹提供Maxwell材料。 接下來，將樹放入場景中以填充合成中的任何空格，并將材質(zhì)應(yīng)用于標(biāo)記。

Step 07: Exporting for MARI

For painting our model in MARI, we first need to make and lay out the UV tiles. MARI supports multiple UV tile layouts, so I will separate the model into its material components, i.e. metal, wheels, paint surfaces, and so on. This will make it easier to select objects, paint objects of the same material, and apply an overall dust texture later.

In the Maya mesh settings, I use the smooth setting with a value of 2, with Preserve > Selection Borders checked. In the UV layout panel, under the UV Texture Editor Grid Options, set the length and width to 10, and the number of subdivisions to 2. This should enable you to preview the full set of UV tiles for MARI.

步驟07：導(dǎo)出MARI

為了在MARI中繪畫我們的模型，我們首先需要制作和布置UV瓷磚。 MARI支持多種UV瓦片布局，因此我將把模型分成其材料組分，即金屬，輪子，油漆表面等。 這將使得更容易選擇對象，繪制相同材料的對象，并且稍后應(yīng)用整體灰塵紋理。

在Maya網(wǎng)格設(shè)置中，我使用值為2的平滑設(shè)置，選中了保留>選擇邊框。 在UV布局面板中，在UV紋理編輯器網(wǎng)格選項下，將長度和寬度設(shè)置為10，將子細(xì)分?jǐn)?shù)設(shè)置為2.這將使您能夠預(yù)覽MARI的完整UV瓦片集。

Step 08: Making sand masks in MARI

To create the effect of sand in crevices, first go to Objects > Ambient Occlusion. Then in the Channel menu, create a new layer and select Geometry > Ambient Occlusion. The ambient occlusion will be created as a procedural layer, so to rasterize this, right-click and select Merge.

By selecting various parts of the geometry, we can use grayscale images to paint natural sand streaks on the AO layer. Try to imagine that what's black will be sand. When you're happy, right-click the AO layer and navigate to Export. It's good practice to rename your exported files according to where they are on the vehicle.

步驟08：在MARI制作防砂口罩

要在裂縫中創(chuàng)建沙子的效果，首先轉(zhuǎn)到對象>環(huán)境遮擋。 然后在“通道”菜單中，創(chuàng)建一個新圖層，并選擇幾何>環(huán)境遮擋。 環(huán)境遮擋將創(chuàng)建為過程層，因此要柵格化它，請右鍵單擊并選擇合并。

通過選擇幾何的各個部分，我們可以使用灰度圖像在AO層上繪制天然砂紋。 試著想象什么是黑色將是沙子。 當(dāng)您快樂時，右鍵單擊AO圖層并導(dǎo)航到導(dǎo)出。 最好根據(jù)車輛上的位置重命名導(dǎo)出的文件。

Step 09: Applying the carbon fiber texture

First we will select our geometry and open the UV tab; this way, we can paint flat. Import the file 'carbon fiber.png' (provided in the downloadable resources) into the image plane and drag it onto the work area. At the top, select Repeat so that the texture will repeat at the edges as we paint. Alternatively, by selecting Stamp, you can fill the entire screen with once click. (Note that this will affect all geometry on the screen at the same time, so make sure only the panels we want carbon fiber on are visible.)

步驟09：應(yīng)用碳纖維紋理

首先，我們將選擇我們的幾何并打開UV選項卡; 這樣，我們可以畫平。 將文件'carbon fiber.png'（在可下載資源中提供）導(dǎo)入圖像平面，并將其拖動到工作區(qū)域。 在頂部，選擇重復(fù)，以便紋理將在我們繪制時在邊緣重復(fù)。 或者，通過選擇Stamp，您可以一次性填充整個屏幕。 （請注意，這將同時影響屏幕上的所有幾何圖形，因此請確保只有我們想要碳纖維的面板才可見。）

Step 10: Interior texturing

I apply the material for the seats in the same way I applied the carbon fiber. I have supplied the seat texture for you in the project files. When applying the seat texture, ensure that the seams and fiber direction run complementary to the seat itself, as it will look much better in the final renders. We can also import images to apply as patches to the seat belts or wherever you wish. Note that it's good practice to apply each material in a separate layer within your channel layer and label it accordingly.

步驟10：內(nèi)部紋理化

我應(yīng)用碳纖維相同的方式應(yīng)用座椅的材料。 我已經(jīng)在項目文件中為您提供了座位紋理。 當(dāng)應(yīng)用座椅質(zhì)地時，確保接縫和纖維方向與座椅本身互補(bǔ)，因為它在最終渲染中看起來更好。 我們還可以導(dǎo)入圖像以作為補(bǔ)丁應(yīng)用于安全帶或任何您想要的地方。 請注意，最佳做法是將每種材料應(yīng)用到您的渠道圖層中的單獨(dú)圖層中，并相應(yīng)地標(biāo)記。

Step 11: Maxwell material overview

In the Maxwell Editor we can create multiple layers of various opacities, and within each layer we can also create BSDF layers, which can contain bump maps, diffuse textures, gloss maps, emitters and displacements. The best workflow is to create the base BSDF first by plugging your image into the Reflectance node. You can lower the Roughness of this to achieve a matte or gloss finish; whatever color or image is plugged into 'Reflectance 90' will become more dominant the lower the Roughness is brought. In the upper layers above this, we can plug in a solid sand color and this can be controlled by an opacity mask made earlier in MARI (or any grayscale image). This way we can layer sand on top of our materials below.

步驟11：Maxwell材料概述

在Maxwell編輯器中，我們可以創(chuàng)建多層不同的不透明度，在每個層內(nèi)，我們還可以創(chuàng)建BSDF層，其中可以包含凹凸貼圖，漫反射貼圖，光澤貼圖，發(fā)射器和位移。 最佳工作流程是首先通過將圖像插入“反射”節(jié)點(diǎn)來創(chuàng)建基本BSDF。 您可以降低粗糙度來獲得無光澤或光澤的表面; 無論何種顏色或圖像被插入“反射90”將變得更顯著，粗糙度越低。 在上面的上層，我們可以插入一個堅實的沙色，這可以通過在MARI早期制作的不透明蒙板（或任何灰度圖像）控制。 這樣我們可以在我們的材料上面層砂。

Step 12: Maxwell material overview

metallic paint: For making a nice metallic paint, we need to start with a deep ruby base with a Roughness of 50. Above this, make a new layer and set it to Additive (this is signified by an 'A' on the layer). On this layer, we'll make the Roughness 25, put a red color in Reflectance and orange in Reflectance 90. Reflectance 90 should always have a lighter color than Reflectance for better falloff light.

Then make another Additive layer above this for the glaze coating, check "Force Fresnel" and lower the Roughness to 0. You can add a new layer above this again, like in the carbon texture, if you want to make the sand mask.

步驟12：Maxwell材料概述

金屬漆：為了制作漂亮的金屬漆，我們需要從一個深度為50的粗糙的紅寶石底部開始。在這之上，做一個新的層，并將其設(shè)置為添加劑（這由層上的“A”表示） 。 在這個層上，我們將粗糙度25，在反射率中為紅色，在反射率90中為橙色。反射率90應(yīng)當(dāng)總是具有比反射率更淺的顏色以獲得更好的衰減光。

然后在上面做另一個添加劑層用于釉料涂層，檢查“強(qiáng)制菲涅爾”，并將粗糙度降低到0.你可以再次添加一個新的層，如在碳質(zhì)地，如果你想制作砂面膜。

Step 13: Maxwell material types

A great way to understand the materials and get started on any new material is to use the materials wizard. When you create a new material by selecting the Global Parameters tab, you can access a range of basic material types under the Type Menu. Alternatively you can access either the Browser at the top and search the thousands of ready-made user materials, or the Local Materials which are made by Maxwell. Always remember when stacking BSDF layers to make sure they collectively add up to 100 to get true results.

步驟13：Maxwell材料類型

了解材料并開始使用任何新材料的一個好方法是使用材質(zhì)向?qū)А?當(dāng)您通過選擇“全局參數(shù)”選項卡創(chuàng)建新材料時，可以在“類型菜單”下訪問一系列基本材料類型。 或者，您可以訪問頂部的瀏覽器，并搜索成千上萬的現(xiàn)成用戶材料或由Maxwell制作的本地材料。 始終記住，當(dāng)堆積BSDF層，來確保他們共同加起來100，來獲得真正的結(jié)果。

Step 14: Maxwell material basic

We can make any image into an Emitter material in the Maxwell Editor. First you must convert that image in Photoshop to a 32-bit format under the Mode tab in the menu, and then save it as an Open EXR. When you create a new Maxwell material by right-clicking on the layers palette, we can 'Create Emitter', and under Type, select 'HDR Image' and plug your image into the material. From here you can also adjust the intensity. I will supply the materials used in this project for you to analyze.

步驟14：Maxwell材料

我們可以在Maxwell Editor中將任何圖像變成發(fā)射體材料。 首先，您必須在Photoshop中將此圖像轉(zhuǎn)換為32位格式，在菜單中的模式選項卡下，然后將其另存為開放EXR。 當(dāng)您通過右鍵單擊圖層調(diào)色板創(chuàng)建新的Maxwell材料時，我們可以創(chuàng)建發(fā)射體，在類型下選擇“HDR圖像”，然后將圖像插入材質(zhì)。 從這里你也可以調(diào)整強(qiáng)度。 我將提供本項目中使用的材料供您分析。

Step 15: Adding fill and kick lights

In this step we will add a fill light and a kick light - also known as a 'kicker' light, a secondary light source that adds extra dimension to the darker side of the subject. One of the great features in Maxwell Render is the Multilight function, which allows us to adjust the lighting intensity and color, post-render.

The first thing we need to do is to add two polygon planes with the normals facing our vehicle. We will then need to apply a Maxwell emitter material to each plain. If you use the FIRE window, you can adjust the intensity and color of these before committing to a final render. These lights will give us extra control over the outcome of our scene.

步驟15：添加填充和踢燈

在這個步驟中，我們將添加一個補(bǔ)光燈和一個踢燈（也稱為“踢球”燈），一個輔助光源，在主體較暗的一側(cè)增加了額外的尺寸。 Maxwell Render的一個重要功能是Multilight功能，它允許我們調(diào)整照明強(qiáng)度和顏色，后渲染。

我們需要做的第一件事是添加兩個多邊形平面，法線面向我們的車輛。 然后，我們將需要對每個平面應(yīng)用Maxwell發(fā)射體材料。 如果使用FIRE窗口，可以在提交到最終渲染之前調(diào)整這些窗口的強(qiáng)度和顏色。 這些燈將給我們額外的控制我們的場景的結(jié)果。

Step 16: The Maxwell Multilight feature

Before you render your scene, you must enable the Multilight feature in the render settings. You can enable it to adjust either light intensity or both intensity and color. Once your render is complete you can slide the dials in the Multilight window and update the scene by hitting Refresh. If you like the image, make sure to save it before adjusting the lights again. This way you can have multiple versions with different lighting from one render. In our final scene I will just use this setting sparingly to bump up some shadows and highlight the paint sparkle so that it looks natural. After taking the final image into Photoshop to tweak the levels, add some atmospheric dust and paint extra sand details under the tires, the car is complete.

步驟16：Maxwell多光照功能

在渲染場景之前，必須在渲染設(shè)置中啟用多光照功能。 您可以啟用它來調(diào)整光強(qiáng)度或強(qiáng)度和顏色。 一旦渲染完成，您可以在“多光”窗口中滑動撥盤，然后通過點(diǎn)擊刷新來更新場景。 如果你喜歡的圖像，確保保存它，然后再次調(diào)整燈光。 這樣，您可以有多個版本，從一個渲染不同的照明。 在我們最后的場景中，我將只使用這個設(shè)置節(jié)省一些陰影和突出的油漆閃耀，使它看起來自然。 在將最終圖像投入Photoshop調(diào)整水平之后，添加一些大氣灰塵，并在輪胎下面繪制額外的沙子細(xì)節(jié)，汽車是完整的。