制作“威利”吉普車

我們是MartinOstrolucky和Rudolf Herstek。我們將一起向您展示創(chuàng)建標(biāo)志性的第二次世界大戰(zhàn)“威利”吉普車模型的步驟。在游戲行業(yè)擁有七年的經(jīng)驗(yàn)后，我們成立了Cassa Game Industry，作為支持年輕游戲開發(fā)者和藝術(shù)家的一種方式。這是我們想與您分享我們的經(jīng)驗(yàn)和為您呈現(xiàn)“威利”吉普車工作流程的原因之一。

We are Martin Ostrolucky and Rudolf Herstek. Together, we're going to show you the steps involved in creating a model of the iconic World War Two "Willys" jeep. After seven years of experience in the games industry, we founded Cassa Game Industry as a way to support young game developers and artists. It is one of the reasons why we want to share our experience with you and present you our workflow of "Willys" jeep.

該項(xiàng)目

“威利”吉普車是第二次世界大戰(zhàn)中最受歡迎的軍用車輛之一.3D模型的第一個(gè)版本創(chuàng)建于2013年，經(jīng)歷了幾個(gè)重大變化，成為您今天看到的AAA游戲資產(chǎn)。您幾乎可以追蹤我們在模型質(zhì)量變化方面的經(jīng)驗(yàn)和技能的提高�？纯聪旅娴膱D片！

The project

The "Willys" Jeep is one of the most popular military vehicles of World War 2. The first version of the 3D model was created in 2013 and has gone through several major changes to become the AAA game asset you see today. You can almost track our increase in experience and skill in the changing quality of the model. Take a look at the images below!

目標(biāo)和參考

一開始我們決定使用高質(zhì)量的PBR紋理來創(chuàng)建AAA游戲模型。我們希望它看起來現(xiàn)實(shí)，而不是程式化，我們還需要一個(gè)模型準(zhǔn)備索具和動(dòng)畫。首先，我們在網(wǎng)上搜索了許多有用的車輛參考資料。我們通過它們進(jìn)行分類，并決定車輛的設(shè)計(jì)，損壞程度，表面顏色以及可用作貼花的相關(guān)符號和文字。

Goal and references

At the beginning we made the decision to create a AAA game model using high quality PBR textures. We wanted it to look realistic, not stylized and we also needed a model ready for rigging and animation. First we searched online for many useful references of the vehicle. We sorted through them and decided upon vehicle design, damage level, surface color, and relevant symbols and texts usable as decals.

三維建模

藍(lán)圖幾乎總能找到真正的對象建模（特別是車輛）。他們是一個(gè)開始的好地方 - 并且可以讓您輕松地塑造大部分關(guān)鍵功能。像www.the-blueprints.com這樣的地方有一個(gè)巨大而有用的藍(lán)圖選擇。理想的藍(lán)圖是四面八方展示的。

3D modeling

Blueprints can almost always be found for real object modeling (vehicles especially). They are a great place to start - and will allow you to easily shape most of the key features. Places like www.the-blueprints.com have a huge and useful selection of blueprints. Ideally a blueprint shows an object from all sides.

高多模型（HP）

許多人會爭論是否最好創(chuàng)建一個(gè)低聚（LP）模型，然后將其平滑到HP模型或其他方式。這在一定程度上取決于項(xiàng)目，但通常在建立獨(dú)特資產(chǎn)模型時(shí)，從HP模型開始更容易和更好。

高多邊形模型（HP）

Many would argue whether it is better to create a low-poly (LP) model and then smoothen it into an HP model or the other way around. It depends on the project to a certain degree but usually it is easier and better to start with a HP model when you model unique assets.

我們把藍(lán)圖放在一個(gè)平面上，離視口中心較遠(yuǎn)，遠(yuǎn)離模型，以免遮擋視線。

We have placed blueprint pictures on a plane, farther from viewport center and farther from the model so that they wouldn't obstruct the view.

我們從大的主要特征開始建模對象，然后轉(zhuǎn)移到更詳細(xì)的對象上。大多數(shù)情況下，平面開始塑造一塊金屬板的最佳選擇。首先根據(jù)藍(lán)圖對其進(jìn)行整形，然后使用外殼修改器添加厚度。為了使它圓滑，我們使用Turbosmooth細(xì)分2-3次。我們總是使用更簡單的對象拓?fù)鋪肀３謱α鞒痰目刂�，而不會在太多的多邊形中丟失。我們將這種方法應(yīng)用于模型創(chuàng)建的幾乎所有方面。

例如，讓我們看看我們?nèi)绾蝿?chuàng)建輪胎設(shè)計(jì)。我們從平面開始，模擬一個(gè)輪胎部門。該圖案在輪胎表面周圍重復(fù)80次，因此足以建模一次，然后在表面上一個(gè)接一個(gè)地復(fù)制。

We modeled the object starting with big main features and then moved to more detailed ones. Most of the time a plane is the best thing to begin shaping a piece of sheet metal. First you shape it according to the blueprint, then you use shell modifier to add thickness. To make it round we use Turbosmooth subdivided 2-3 times. We always work with simpler object topology to maintain control over the process, and not get lost in too many polygons. We apply this approach to almost all aspects of the model creation.

For example let's see how we created the tire design. We started with the plane and modeled one tire sector. The pattern repeats itself 80 times around the tire surface so it is enough to model it once and then copy it one after another over the surface.

使用焊接功能，我們連接所有的小部件，然后添加兩個(gè)彎曲修改器。第一個(gè)創(chuàng)造凸面，第二個(gè)彎曲平面一個(gè)圓圈。最后我們用焊接頂點(diǎn)來完成輪胎。如果您在關(guān)閉圓圈時(shí)遇到困難，建議您在添加重置xform并將對象設(shè)置為透視，然后再移至“彎曲”修改器。

Using the weld function we connected all the little parts and then added two bend modifiers. The first one created convexity and the second one bent the plane to a circle. Finally we used weld vertices to finish the tire. If you have trouble to close a circle, we recommend adding reset xform and setting the object to pivot before you move on to bend modifier.

最后的結(jié)果是這樣的：

And the final result look like this:

用布制成的物體（如座墊或換檔蓋）最好在ZBrush中創(chuàng)建。在從ZBrush導(dǎo)出HP模型之前，我們建議使用抽取主控函數(shù)來減少模型。它可以降低數(shù)百萬的數(shù)量，而不會有明顯的視覺變化，這對于烘焙工作流程是有利的。

Objects made of cloth (eg. seat padding or the gear shift cover) are best created in ZBrush. Before you export a HP model from ZBrush, we recommend reducing the model using the decimation master function. It can lower the poly count by millions without a significant visual change which is good for the baking workflow.

低聚模型（LP）

最終的HP模型經(jīng)歷了一個(gè)反饋階段;我們做了一些最后的改變，并推進(jìn)到LP建模階段。只要模型具有良好的拓?fù)浣Y(jié)構(gòu)，您只需要移除支撐幾何體并將對象優(yōu)化為最少的必要多邊形。

例如，用于LP車型的吉普車身僅由一個(gè)大型整體車身組成，但對于HP車型來說，使用更多元素并避免在某些情況下可能導(dǎo)致問題的不受歡迎的效果更為有效。讓我們看看我們?nèi)绾卧谶@一個(gè)工作：

Low-poly model (LP)

The final HP model went through a feedback phase; we made some last changes and advanced to the LP modeling phase. As long as a model has a good looking topology, all you need to do is to remove supporting geometry and optimize the object to a minimum of necessary polygons.

For example the Jeep bodywork for LP models consists of just a big monoblock, but for a HP model it is more effective to use more elements and avoid unwelcome effects that may cause problems in some cases. Let's see how we work on this one:

模型（A）：你可以看到它的幾何形狀適合于一個(gè)立方體，但是它對底部的彎曲區(qū)域是有害的。解決方案可能是將立方體作為單獨(dú)的元素（B），但是在立方體與曲面區(qū)域之間缺乏自然的曲面連接。如果聯(lián)合區(qū)域非常重要，而且不能使用支撐幾何體，則可以創(chuàng)建第三個(gè)模型，將前兩個(gè)模型結(jié)合起來，而不是與它們中的任何一個(gè)連接（C）。

Model (A): you can see its geometry is suitable for a cube but it is harmful for the curved area at its base. A solution may be to have the cube as a separate element (B) but you would lack a natural curved joint between the cube and the curved area. If the joint area is very important and you can't use supporting geometry, you can create a third model which combines the first two and isn't connected to any of them (C).

解開模型

在進(jìn)行紋理處理之前，我們不得不拆開吉普車。您可以在下面的各種模型部件上看到紋理像素密度。棋子越小，像素密度越高。例如，為了展開模型，我們使用了比大多數(shù)其他模型零件組合所需的更多空間來放置小文本板。

Unwrapping a model

Before moving on to texturing we had to unwrap the jeep. You can see texture pixel density on various model parts below. The smaller a checker, the higher pixel density. For example to unwrap the model we used more space for small text plates than we needed for most other model parts combined.

在展開布局過程中，我們也強(qiáng)烈建議從較大的對象開始，最后做最小的。 在大物體之間的間隙中放置小物體更容易。

During the unwrap layout, we also highly recommend starting with larger objects, and doing the smallest ones last. It's easier to place small objects in gaps between big objects.

紋理烘焙

在開始進(jìn)行紋理烘焙之前，有一些必須遵守的規(guī)則。其中一些是：

1.關(guān)于物體拓?fù)浣Y(jié)構(gòu)切割UV縫

2.關(guān)于Unwrap設(shè)置平滑組

3.爆炸LP和HP對象以避免失真問題

我們分解了LP模型和HP模型（爆炸），以便它們的部分重疊，將它們導(dǎo)出到FBX并使用xNormal對其進(jìn)行烘焙。

Baking textures

Before you start with texture baking, there are some mandatory rules to stick to. Some of these are:

1.    Cut UV seams with regard to the object topology

2.    Set Smoothing groups with regard to Unwrap

3.    Explode LP and HP object to avoid artifact glitches

We decomposed the LP model and the HP model (explode) so that their parts overlap, exported them to FBX and baked them using xNormal.

即使你遵守所有的規(guī)則，神器故障是常見的出現(xiàn)。要解決這個(gè)問題，您可以創(chuàng)建多個(gè)使用應(yīng)用程序Photoshop組合的法線貼圖紋理。然后使用蒙版，選擇完美烘焙的紋理部分。由此產(chǎn)生的紋理將變成無偽影的。

我們將法線貼圖和吉普車FBX模型加載到物質(zhì)渲染器上，并烘焙剩余的其他貼圖 - 環(huán)境，曲率，世界空間，位置和厚度。我們使用導(dǎo)入的法線貼圖來代替從HP模型中烘焙。原因是它已經(jīng)有了所有的烘烤階段的文物糾正。因此，我們避免修復(fù)可能出現(xiàn)在附加地圖上的工件。

Even if you heed all the rules, artifact glitches are common to appear. To fix this, you can create multiple normal map textures that you combine using application Photoshop. Then using masks you select texture parts that are flawlessly baked. The resulting texture will then become artifact-free.

We loaded the normal map and the jeep FBX model to Substance Painter and baked remaining additional maps - Ambient, Curvature, World Space, Position and Thickness. Instead of baking from the HP model we use the imported normal map. The reason is that it already has all the artifacts from the baking phase corrected. Therefore we avoided fixing artifacts that could have had appeared on additional maps.

從法線貼圖烘烤更多貼圖時(shí)，請不要忘記取消選擇“正�！保�并選中“使用低多邊形網(wǎng)格作為高度多邊形網(wǎng)格”。

When baking additional maps from the normal map do not forget to unselect Normal and check Use Low Poly Mesh as High Poly Mesh.

紋理

參考資料幫助我們假定吉普車制造的材料，結(jié)構(gòu)是什么，表面細(xì)節(jié)如何，污垢聚集在哪里以及哪些部件最容易受到損壞。對于紋理，我們使用了Substance Painter 2.6.2。

在我們將吉普車導(dǎo)入物質(zhì)噴涂車之前，我們將它的UV貼圖分為兩個(gè)紋理集 - 吉普車身（不透明材質(zhì)）和Windows +燈光（半透明材質(zhì)）。

Texturing

References helped us to assume what materials the jeep is made of, what its structure is, what its surface details are, where does dirt gather, and which parts are most often susceptible to damage. For textures we used Substance Painter 2.6.2.

Before we imported the jeep to Substance Painter, we divided its UV map to two texture sets - Jeep Body (opaque material) and Windows + Lights (translucent material).

后來我們意識到將更多的UV貼圖應(yīng)用于吉普車會更實(shí)用一些。它大大加快了與物質(zhì)涂料工作，并改善項(xiàng)目監(jiān)督。

我們總是開始一個(gè)基本材料分配的紋理過程。您可以在架子上找到它們，或者可以使用物質(zhì)來源下載它們。首先，我們將每輛吉普車的部件（車身，車輪，座椅）分配給一個(gè)材料 - 金屬板，金屬，橡膠，塑料，皮革等等，并創(chuàng)建了18個(gè)主要組別。

Later on we realized it would be more practical to apply more UV maps to the jeep. It significantly speeds up work with the Substance Painter and improves project supervision.

We always start a texturing process with basic material assignment. You can find them in shelf or you can download them with Substance source. First we have assigned every jeep part (bodywork, wheels, seats) with only one material - sheet metal, metal, rubber, plastic, hide, and so on, and created 18 main groups.

第一個(gè)材料版本誕生了。為了保存紋理邏輯，我們選擇從宏觀到微觀結(jié)構(gòu)。換句話說，先定義一個(gè)基礎(chǔ)材料，然后再添加細(xì)節(jié)。

The first material version was born. To preserve texturing logic we chose to go from macro- to microstructure. In other words to define a base material first and then add the details after.

這就是我們?nèi)绾伟才抛�位層組。

That is how we arranged layers group for the seats.

多虧了面具發(fā)生器，它可以快速和容易地制造面具。你可以立即知道一個(gè)項(xiàng)目是如何形成的。對我們來說，這只是一個(gè)開始。

Thanks to mask generators it is quick and easy to create masks. You can immediately tell how a project shapes up. For us, that was just a beginning though.

我們想要感覺到我們的模型真的很獨(dú)特。我們已經(jīng)手動(dòng)重繪了蒙版，大部分時(shí)間都是使用畫筆和投影工具。這樣我們避免了一個(gè)通用和隨機(jī)的面具外觀。

We wanted to feel that our model was really unique. We have repainted the mask manually, most of the time using brushes and projection tool. This way we avoided a mask look that felt generic and random.

面具的質(zhì)地質(zhì)地改善了現(xiàn)實(shí)的整體感覺。使用貨架上的或在網(wǎng)上找到一些�？聪旅嫖覀兪褂玫睦�子。

A quality texture for masks improved the overall feeling of realism. Use those from shelf or find some online. See examples of those we used below.

演示和渲染

我們決定如何呈現(xiàn)吉普車是非常重要的。我們創(chuàng)建了一個(gè)充滿概念和汽車照片的參考表。這有助于我們選擇一個(gè)攝像頭的角度和照明，使吉普車脫穎而出。那么這只是嘗試不同的預(yù)覽渲染的問題。為了渲染我們使用應(yīng)用V-Ray的模型。

早期我們一直在努力達(dá)到最佳的顏色和渲染設(shè)置。我們發(fā)現(xiàn)你需要遵守這些規(guī)則：

1.在Gamma和LUT設(shè)置中，將Gamma校正設(shè)置為2.2，勾選啟用Gamma / LUT，影響顏色選擇器和材質(zhì)編輯器

2.使用Allegorithmic從應(yīng)用程序Substance Painter設(shè)計(jì)的V-Ray預(yù)設(shè)輸出紋理。使用TIF 16位格式

3.使用重寫2.2將漫反射貼圖導(dǎo)入3ds Max

4.將伽馬倍率設(shè)置為1.0（正常，光澤度，反射，IOR，高度）導(dǎo)入所有其他紋理。

5.將BRDF設(shè)置為Microfacet GTR（GGX） - 只有更新的V-Ray版本

6.檢查V-Ray材質(zhì)設(shè)置中的光面菲涅耳

7.您可以使用高度紋理作為位移貼圖，但會使渲染非常消耗內(nèi)存

8.將導(dǎo)入的紋理添加到：Diffuse =漫反射貼圖？反思=反映地圖？光澤度= RGlossiness地圖？ IOR =菲涅耳IOR圖？凹凸（值100）= VRayNormalMap =法線貼圖

Presentation and rendering

It was important to us to decide how we wanted to present the jeep. We created a reference table full of concepts and car photos. That helped us to choose a camera angle and lighting to make the jeep stand out. Then it was just a matter of trying out different preview renders. To render the model we used application V-Ray.

Early on we have struggled to reach optimum color and rendering setting. We found out that you need to follow these rules:

1.    In Gamma and LUT settings, set Gamma correction to 2.2, check enable Gamma/LUT, Affect color selector and material editor

2.    Export textures with V-Ray preset designed by Allegorithmic from application Substance Painter. Use TIF 16-bit format

3.    Import diffuse texture into 3ds Max with override 2.2

4.    Import all the other textures with gamma override set to 1.0 (normal, glossiness, reflection, IOR, height)

5.    Set BRDF to Microfacet GTR (GGX) - only newer V-Ray versions

6.    Check Glossy Fresnel in V-Ray material settings

7.    You can use Height texture as a Displacement map but it would make rendering very memory consuming

8.    Put imported textures to: Diffuse=Diffuse map ? Reflection=Reflect map ? Glossiness=RGlossiness map ? IOR=Fresnel IOR map ? Bump (value 100)=VRayNormalMap=Normal map

下圖顯示了V-Ray材質(zhì)設(shè)置。

The image below shows V-Ray material settings.

我們使用了兩個(gè)V-Ray燈光和一個(gè)帶HDRI紋理的V-Ray頂燈，以支持逼真的反射效果。其他相機(jī)和燈光設(shè)置根據(jù)我們的審美感受已經(jīng)經(jīng)歷了多次變化。

We used two V-Ray lights and one V-Ray dome light with HDRI texture to support realistic reflections. Other cameras and lights settings have been subjected to multiple changes based on our aesthetic feelings.

結(jié)論

我們想補(bǔ)充一點(diǎn)，如何創(chuàng)建一個(gè)游戲資產(chǎn)并不存在最終和最優(yōu)的方式。 如果只用一個(gè)應(yīng)用程序替換一個(gè)應(yīng)用程序，則會對工作流程產(chǎn)生重大影響，并帶來新的優(yōu)點(diǎn)和缺點(diǎn)。 畢竟，重要的是最后的結(jié)果。

Conclusion

We would like to add that there is no ultimate and superior way of how to create a game asset. If you replace just one application with another one, it makes a significant workflow impact and brings in new advantages and disadvantages. After all, what matters is the final result.