制作“CG繪畫”工具（二）

紋理

Texturing

為了制作紋理，我基本上使用了我自己的照片，并在Photoshop中畫出來(lái)。在某些情況下，我部分使用了來(lái)自互聯(lián)網(wǎng)的照片和我的紋理庫(kù)。大部分的物體都被涂上了油漆，所以在每一個(gè)物體上分別畫出紋理是不合理的，而且會(huì)非常耗時(shí)。因此，我在Photoshop中創(chuàng)建了用alpha通道繪制高分辨率圖像。然后，我可以改變它的透明度、對(duì)比度和飽和度，不管它是木材、金屬還是塑料的紋理。我需要確保它看起來(lái)不太明顯，因?yàn)樗鼤?huì)引起不同類型的紋理(圖12)。(我無(wú)法告訴你我是如何為木材或塑料制作紋理的，因?yàn)檫@是一個(gè)嚴(yán)肅的主題，花了很多時(shí)間。)

For the preparation of textures, I basically used my own photos and drew them in Photoshop. In some cases I partially used photos from the Internet and my library of textures. Most of the objects were going to be smeared with paint, and so to draw textures with paint on each object separately was not rational and would have been very time-consuming. I therefore created in Photoshop the image of spots of paint in the high-res with an alpha-channel. I could then impose this image, change its transparency, contrast and saturation on any texture, whether it was a texture for wood, metal or plastic. I needed to make sure that it was not so strongly pronounced as to cause tiling on different types of textures (Fig.12). (I cannot tell you how I created the texture for the wood or plastic because it was a serious theme and took a lot of time.)

圖12

對(duì)于大多物體(有一些銘文)，我制作了獨(dú)特的紋理。我沒(méi)有打開包裝，也沒(méi)有使用unwrap UVW，因?yàn)樵谶@個(gè)階段的工作中沒(méi)有這樣一個(gè)復(fù)雜的對(duì)象。對(duì)于texturing來(lái)說(shuō)，沒(méi)有足夠的標(biāo)準(zhǔn)形式的UVW映射;在某些情況下，我使用不同的映射和不同的結(jié)構(gòu)，在物體的側(cè)面，它比高級(jí)的不包裝更快。多虧了這一點(diǎn)，我節(jié)省了很多時(shí)間，在最后的結(jié)果中你不能說(shuō)我走了這樣的捷徑。

For many objects (where there are some inscriptions) I made unique textures. I did not unwrap and did not use Unwrap UVW, as at this stage of the work there was not such a complex object. For texturing there would not be enough standard forms of UVW mapping; in some cases I used different mapping and different structures for the sides of the objects and it was quicker to do than high-grade unwraps. Thanks to this alone, I saved a lot of time, and you cannot tell in the final result that I took such shortcuts.

為了進(jìn)一步解釋，我只是調(diào)整了紋理大小和對(duì)象的大小。在幾乎在所有相同或相似的對(duì)象上，紋理有不同的著色和不同的映射。繪制紋理時(shí)，需要考慮的是，在角落和屋檐下，物體，作為一個(gè)規(guī)則，會(huì)看起來(lái)更破舊，更暗的是灰塵和灰塵的堆積。我給這個(gè)場(chǎng)景更多的光線，還用不同的筆刷在Photoshop中涂抹了一些區(qū)域;在大多數(shù)情況下，標(biāo)準(zhǔn)的刷子就足夠了。這些細(xì)微的差別在油漆、顯示器和板材的紋理上都是可見的。在光線方面，紋理應(yīng)該多多少少都是中性的，而且在光線的照射下也不應(yīng)該有任何強(qiáng)烈的陰影，否則，在渲染過(guò)程中，不同的光線照射會(huì)產(chǎn)生一種人造的外觀。在畫的紋理上，陰影是可見的，我把它變成了鐵銹，因?yàn)殛幱暗年幱皶?huì)使觀眾迷惑，看起來(lái)更像真正的鐵銹(圖13)。

To further explain, I simply adjusted the size of textures to the size of objects. On practically all identical or similar objects the textures had different shaders and different mapping. Drawing textures, it was necessary to consider the fact that in corners and under ledges, objects, as a rule, would look shabbier and darker from the accumulation of dust and dirt. I gave more light to the scene and also blacked out some areas in Photoshop, using various brushes; in the most cases the standard brushes were enough. These nuances are visible on the textures of paints, the monitor and boards, etc. Textures should be more or less neutral in terms of lighting, and there should not be any strongly pronounced shadows on them, otherwise, during rendering, the different light exposure will give an artificial look. On the texture of the paints a shadow is visible, which I transformed to rust because the unclear shadow can confuse viewers and look more like real rust (Fig.13).

圖13

陰影

Shading

這是一個(gè)相當(dāng)困難的主題，有許多不同之處，但我將試著簡(jiǎn)要描述一下我的方法。在遮陽(yáng)階段，需要考慮不同材料的真實(shí)特性。不幸的是，當(dāng)調(diào)整材料進(jìn)入有效的物理參數(shù)時(shí)，結(jié)果并不總是令人滿意。這并不奇怪，因?yàn)楹艽蟪潭壬先�決于光的調(diào)整，光源到物體的距離，相機(jī)傾斜角度等等。所以要調(diào)整材料，我們必須使用實(shí)驗(yàn)方法。我們希望知道函數(shù)的參數(shù)是什么。我在大多數(shù)情況下使用標(biāo)準(zhǔn)材料。在我看來(lái)，沒(méi)有必要在所有情況下使用高級(jí)著色器，因?yàn)樗鼈兪恰案呒?jí)的”。只有在使用標(biāo)準(zhǔn)材料時(shí)才能達(dá)到效果。這樣的方法可以節(jié)省大量的時(shí)間，在材料的調(diào)整和渲染期間。

This is a rather difficult theme and there are many differences, but I will try to briefly describe my approach to it. At the stage of shading, it was necessary to consider real characteristics of the different materials. Unfortunately, when adjusting materials to enter the valid physical parameters, the result is not always satisfactory. There is nothing surprising about this though, as a lot depends on the adjustments of light, the distance from light sources to objects, the corner of an inclination of the camera, etc. So to adjust materials we have to use an experimental method. It is desirable to know what functions parameters have. I basically use standard materials in most cases, when they are enough. In my opinion there is no need to use advanced shaders in all cases just because they are "advanced". They should be only used to achieve an effect when using standard materials is impossible. Such an approach helps to save a lot of time, both during the adjustment of materials and during rendering.

正如前面提到的，我使用Mental Ray作為我的渲染器，在大多數(shù)情況下是標(biāo)準(zhǔn)著色器。這很方便，因?yàn)槲铱梢钥焖僬{(diào)整材料，使用掃描線進(jìn)行測(cè)試。通常情況下，當(dāng)使用心理光線渲染時(shí)，材料看起來(lái)幾乎是一樣的，甚至更好。這是測(cè)試它們的一種更方便的方法，而不是調(diào)整著色器并進(jìn)行高級(jí)渲染，這使您等待測(cè)試結(jié)果的時(shí)間很長(zhǎng)。

As already mentioned, I use Mental Ray as my renderer, and in most cases standard shaders. This was convenient because I could adjust materials rather quickly, using Scanline for test renders. As a rule, when rendering using Mental Ray, materials look approximately the same and even better. It is a more convenient way to test them than to adjust shaders and make advanced renders which make you wait a long time for the results of the tests.

當(dāng)創(chuàng)造木材的著色時(shí)，有必要考慮木材幾乎沒(méi)有高光，除了漆木。金屬有強(qiáng)烈的亮點(diǎn)，可以反射周圍的物體;如果沒(méi)有什么反應(yīng)，那么金屬就會(huì)看起來(lái)很差。我們必須創(chuàng)造環(huán)境，或者如果可能的話在反射或使用HDRI上應(yīng)用紋理。有兩種類型的塑料:啞光和光澤。使用SSS為光面塑料，最好是用砂紙，紙，橡膠。雖然有許多不同的變體，但作為一個(gè)規(guī)則，SSS是不需要的。同樣重要的是不要忘記bump，位移，鏡子等。如果我們使用它們，就有可能取得很好的效果!它們的位圖不同于漫射，但對(duì)于平均和遠(yuǎn)距的平面來(lái)說(shuō)，它足以在凹凸、鏡面等方面使用。在不同的光照條件下，材料的表現(xiàn)會(huì)不同。在最后的燈光舞臺(tái)后，我必須修正所有的陰影，其中SSS和反射被應(yīng)用。圖14是材料編輯器的一些材料的截屏。

When creating shaders of wood, it is necessary to consider that wood has practically no highlights, except for varnished wood. Metal has strong highlights that can reflect objects around it; if there is nothing to reflect then the metal will look poor. We have to create the surroundings, or if possible apply textures on the reflection or use HDRI. There are two types of plastic: matte and glossy. It is better to do matte plastic, paper, rubber, using SSS for glossy plastic. As a rule SSS is not required, although there are lots of different variants. It is also important not to forget about bump, displacement, specular, etc. If we use them right then it is possible to achieve very good results! It is desirable that the bitmap on them differs from diffuse, but for average and distant planes it is enough to use diffuse on bump, specular, etc. Materials will behave differently under different lighting conditions. After the final lighting stage I had to correct all shaders in which SSS and reflection were applied. In Fig.14 are screenshots of some materials from the material editor.

圖14

照明

Lighting

調(diào)整燈光是我最喜歡的舞臺(tái)之一。良好的照明可以改善適當(dāng)?shù)男蜗?糟糕的燈光會(huì)毀了一件作品。為了節(jié)省時(shí)間，我決定用灰色的材料來(lái)調(diào)整燈光，因?yàn)闉榱诉m應(yīng)良好的照明，需要有一些初步的渲染。

Adjusting the lighting is one of my favourite stages. Great lighting can improve an adequate image; bad lighting can ruin a masterpiece. To save the time I decided to adjust lighting using grey materials, since for the adjustment of good lighting it is necessary to have a number of preliminary renders.

有必要模仿陽(yáng)光，我決定使用日光系統(tǒng)，但我必須用3ds Max 2008代替3ds Max 8，因?yàn)?ds Max 8還不夠好。在調(diào)整陽(yáng)光的時(shí)候，有必要記住，太陽(yáng)的光有一個(gè)溫暖的陰影，但是所有的陰影都有一個(gè)寒冷的，藍(lán)色的陰影，僅僅因?yàn)殛幱皡^(qū)域反映了天空的顏色。還有必要考慮一下，太陽(yáng)的陰影會(huì)變得更暗，因?yàn)樗鼈儊?lái)自投射陰影的物體。使用絕對(duì)精確的陰影是不可能的;這與現(xiàn)實(shí)情況非常相似(圖15)。在3ds Max 2008中，日光系統(tǒng)已經(jīng)充分實(shí)現(xiàn)，照明的調(diào)整也沒(méi)有特別的問(wèn)題。

It was necessary to imitate sunlight and I decided to use the Daylight System, but I had to replace 3ds Max 8 with 3ds Max 2008, as 3ds max 8 was not enough for a good result. When adjusting sunlight, it was necessary to remember that the light of the sun has a warm shade, but all shadows have a cold, bluish shade to then, simply because shadowed areas reflect the colour of the sky. It was also necessary to consider the fact that shadows from the sun become dimmer the further they are from an object projecting a shadow. It is impossible to use absolutely precise shadows; this is a very rough similarity of what it would be like in reality (Fig.15). In 3ds Max 2008 the Daylight System is realised well enough and the adjustment of lighting has no special problems.

圖 15

紋理

Texturing

當(dāng)我們選擇了透視，并調(diào)整了光線，就可以開始用小的東西填充一個(gè)舞臺(tái)，研究周圍環(huán)境的細(xì)節(jié)。通過(guò)圖形平板電腦，我制作了一些大致的草圖，然后以它們的頂部為模板。我認(rèn)為這樣的方法是有效的，它也節(jié)省了時(shí)間。在最后階段，沒(méi)有必要思考和猜測(cè)如何填補(bǔ)空白;我可以很快地畫很多草圖，然后從中選擇一些東西。此外，還可以并行解決所有的合成和顏色問(wèn)題(圖16)。

When the foreshortening had been chosen and the light was adjusted, it was possible to start filling a stage with small things and study the details of the surroundings. By means of a graphics tablet I made some approximate sketches and then modelled on top of them. I considered such an approach effective enough - it also saved time. During the final stage it was not necessary to think and guess about how to fill empty spaces; I could rather quickly draw lots of sketches and choose something from them to build upon. Besides, it was also possible to solve all compositing and colour problems in parallel (Fig.16).

圖 16

后來(lái)，我開始做草和背景;為此，我將所有對(duì)象轉(zhuǎn)換成灰色的材料，因?yàn)檫@部分需要大量的資源。我決定用超級(jí)草插件來(lái)做草。我為草做了很多準(zhǔn)備，有不同的高度，厚度和分布在一平方米。然后我在編輯網(wǎng)格中轉(zhuǎn)換了所有這些，通過(guò)優(yōu)化修改器來(lái)優(yōu)化，并手動(dòng)擴(kuò)展它，在我看來(lái)，在持續(xù)的吹風(fēng)的影響下，山丘上的低草會(huì)生長(zhǎng)。這可能不是創(chuàng)造草的最好方法，但它讓我能夠很好地監(jiān)督很多方面(圖17)。

Afterwards, I began to do the grass and the background; for this purpose I transformed all objects into a grey material because so many resources were demanded for this part. I decided to make the grass by means of the Super Grass plug-in. I made plenty of preparations for the grass, with different heights, thicknesses and distribution over a square metre. I then converted all of this in Edit Mesh, optimised by means of the Optimize modifier and manually spread it out how, in my opinion, low grass on hills would grow under the influence of constant blowing winds. This was probably not the best way of creating grass, but it allowed me to supervise many aspects well enough (Fig.17).

圖17

草地和背景吃掉了大部分的資源，所以我必須把最后的圖像呈現(xiàn)在圖層中:顏料盒、草和背景。用了大約2天的時(shí)間把它呈現(xiàn)在高分辨率下，所有的層都用于所有的透視。我用景深渲染了它，也用了全局照明和最后整理，因?yàn)樗鼈円黄鹫故玖顺隽撕芎玫慕Y(jié)果。

The grass and background ate a lion's share of resources, so I had to render the final image in layers: the paint box, grass and background separately. It took about 2 days to render it in high resolution, with all layers for all foreshortenings. I rendered it with Depth of Field, and also with Global Illumination and Final Gather, since together they give very good results.

最后，輪到后期制作了，我用Photoshop。我沒(méi)有匆忙地做了這篇文章，因?yàn)閺膱D像中獲得了一個(gè)突破，并獲得了一個(gè)新的視角，可以看到一些缺乏的領(lǐng)域。在后期處理的最后階段之前，我看了很多高質(zhì)量的三維和二維的作品，還有幾部皮克斯的電影，以分散我對(duì)自己作品的注意力。在我看來(lái)，這種方法可以提高你在藝術(shù)上的品位，從而幫助你注意到你在工作中所忽略的工作上的差異。當(dāng)你長(zhǎng)時(shí)間的工作并且沒(méi)有休息的時(shí)候，發(fā)現(xiàn)問(wèn)題變得更加困難。

Finally, the turn of post-production came, for which I used Photoshop. I did the post work without rushing, as by having a break from the image and getting a fresh perspective on it, it was possible to see some areas that were lacking. Before the final stage of post-processing I looked at a lot of high quality three-dimensional and two-dimensional work, and also a couple of films from Pixar to distract myself from my own work. In my opinion, this method allows you to raise your taste in art taste up a level, and as a result helps you to notice differences in your work which you will have missed when working on an image for a few weeks. When you're working on something for a long time and without breaks, it becomes more difficult to notice problems.

為了完成這篇文章，這里有一些展示后期制作階段的圖像，以及最終的圖像(圖18 - 19)。謝謝你的關(guān)注。

To complete this article, here are some images showing the stages of post-production, along with the final image (Fig.18 - 19). Thanks for your attention.

圖 18

圖 19