使用Houdini和Mantra創(chuàng)建抽象圖像

了解Niels Prayer如何使用Houdini和Mantra創(chuàng)建抽象圖像...

Discover how Niels Prayer's creates abstract images with Houdini and Mantra...

Storm is an abstract piece created in Houdini and rendered in Mantra. The power in using a software like Houdini is that it's an FX-oriented package. You can really control every step of process and procedurally modify and customize during the process of creation. It's a really pleasant way to work, having the freedom to make modifications at every step without destroying anything you've built. This image is a great example of the power of this way of working. When I start a project like this one, I have an idea, but I know it will evolve thanks to the procedural approach of this software. The FX-oriented aspect allows you to easily generate really fun effects in combination with others; for example, having particles, curves, fluids and pyro effects in the same scene. It doesn't matter if you don't have any model or setup; you can go from scratch to an abstract piece in few hours, from idea to final render.

風暴是在Houdini和Mantra創(chuàng)造的一個抽象的部分。 使用像Houdini這樣的軟件的力量是它是一個面向外匯的包。 你可以真正地控制過程的每一步，并在創(chuàng)建過程中進行程序修改和自定義。 這是一個非常愉快的工作方式，有自由修改在每一步，而不破壞任何你已經(jīng)建立的。 這個圖像是這種工作方式的力量的一個很好的例子。 當我開始一個像這樣的項目，我有一個想法，但我知道它會發(fā)展，由于這個軟件的程序方法。 面向外匯的方面，您可以輕松生成真正有趣的效果與他人結合; 例如，在同一場景中具有粒子，曲線，流體和熱解效應。 沒關系，如果你沒有任何模型或設置; 你可以從頭到抽象的作品在幾個小時內(nèi)，從想法到最終渲染。

In this making-of, you will see how I've managed a particle system to create trails and metallic curves in conjunction with spheres to create an abstract flower shape. I've also played with effects such as smoke and detailed particles to frame the image and create the overall mood. Finally, we'll cover the lighting and rendering steps and how I've put the final touches in compositing to fine-tune the atmosphere. Thanks for reading and I hope you like it!

在這個制作中，你將看到我是如何管理粒子系統(tǒng)創(chuàng)建軌跡和金屬曲線結合球體創(chuàng)建一個抽象的花形狀。 我也玩過的效果，如煙霧和詳細的粒子框架的圖像和創(chuàng)造整體的心情。 最后，我們將介紹照明和渲染步驟，以及我如何在合成中最終完成微調(diào)氣氛。 感謝閱讀，我希望你喜歡它！

Step 01: Particle SOP

For this particular scene, I wanted to have a dark, cloudy mood and play with the contrast of textures and shapes. The opposition of materials, such as clouds and metallic shaders for instance, is a great way to create detailed depth in an image. Playing with lighting, specular highlights, bouncing lights, and create eye-catching details will put your image in another dimension. The viewer is really sensitive to details in an abstract piece, so you have to create catchy elements! Even if it's a poetic vision, in my opinion, you have to put a notion of reality that the viewer can identify with.

First, we start with a particle system done with a Particle SOP (Surface Operator). With some custom forces made with metaballs and turbulences (directly into the Particle SOP node), I've created this pattern to fit my composition. I wanted to create a squared ratio image, with an organic shape rising up, so I've generated my particle system more on the Y and Z axis than the X axis. With a really tiny focal length, it will be really effective when I add the depth of field in comp.

步驟01：粒子SOP

對于這個特定的場景，我想有一個黑暗，多云的心情和戲劇的紋理和形狀的對比。材料的對立，例如云和金屬著色器，是在圖像中創(chuàng)建詳細深度的一種很好的方法。使用照明，鏡面高光，彈跳燈和創(chuàng)造引人注目的細節(jié)將把你的形象在另一個維度。觀眾對一個抽象的部分中的細節(jié)真的很敏感，所以你必須創(chuàng)建引人入勝的元素！即使這是一個詩意的視覺，在我看來，你必須給觀眾可以識別的現(xiàn)實的概念。

首先，我們從粒子SOP（表面運算符）開始粒子系統(tǒng)。有了一些自定義力量的metaballs和湍流（直接進入粒子SOP節(jié)點），我創(chuàng)造了這種模式，以適應我的組成。我想創(chuàng)建一個平方比的圖像，有機形狀上升，所以我已經(jīng)生成我的粒子系統(tǒng)在Y和Z軸比X軸。有了一個非常小的焦距，它將真正有效，當我添加景深在comp。

Step 02: Converting to curves

To create these trails, I converted my particles into curves. When I generated my points, I simulated some main particles and, with a Solver SOP, I merged the previous and next frames of the simulation to create nice trails of particles. In my simulation, I added an "id" attribute on my points so I could get the point numbers and generate curves on each trails. For that, I used an Add SOP in Polygons and "id" for attribute group method. I now have nice curves trails following my particle simulation.

步驟02：轉(zhuǎn)換為曲線

要創(chuàng)建這些蹤跡，我把我的粒子轉(zhuǎn)化為曲線。當我產(chǎn)生了觀點，我模擬了一些主要的粒子，以求解SOP，我合并了前一個和下一個模擬框架，以創(chuàng)建粒子的好蹤跡。 在我的模擬中，我在我的點上添加了一個“id”屬性，所以我可以獲得點數(shù)，并在每個軌跡上生成曲線。 為此，我在多邊形中使用了Add SOP，對于屬性組方法使用了“id”。 我現(xiàn)在有很好的曲線跟蹤我的粒子模擬。

Step 03: Converting to polygons

I knew for this image I wanted some rough metallic shapes for the curves. The problem was that my trails were just some NURBS curves, so I wouldn't be able to apply the textures for roughness or reflectivity later in Mantra. I needed to convert them to polygons and create a basic UV system. So I used a Polywire SOP to convert the curves into polygons, and generated basics UVs with a UV Texture SOP. This meant I could add details to my trails' material for the shading process later.

步驟03：轉(zhuǎn)換為多邊形

我知道這個圖像是我想要一些粗糙的金屬形狀的曲線。 問題是，我的蹤跡只是一些NURBS曲線，所以我不能在 Mantra里應用紋理粗糙度或反射性。 我需要將它們轉(zhuǎn)換為多邊形并創(chuàng)建一個基本的UV系統(tǒng)。 所以我使用了一個Polywire SOP將曲線轉(zhuǎn)換為多邊形，并用UV紋理SOP生成基本UV。 這意味著我可以添加細節(jié)到我的蹤跡的材料以后的著色過程。

Step 04: Converting to polygons

At the beginnings of the trails, I wanted to have a sphere to give a floral look to this abstract shape. When I simulated the particles, I grouped the main ones with a Group SOP for this step. With a Copy SOP and a couple of random expressions (for the size, mostly) in the stamp attributes, I put some spheres randomly at the beginnings of my trails. This gave me the final flower-like appearance I wanted for these trails.

步驟04：轉(zhuǎn)換為多邊形

從小徑的開始，我想有一個球體給這個抽象的形狀花卉的外觀。 當我模擬粒子，我分組主要的與這個步驟的組SOP。 使用復制SOP和幾個隨機表達式（對于大小，大多數(shù)）在戳屬性，我把一些球體隨機在我的蹤跡的開始。 這給了我想要的這些足跡的最終花狀的外觀。

Step 05: Creating extra details

For this type of image, I like to play with contrast of shape, textures and materials. I felt my composition was a little simple at this stage, so decided to generate some particles around my main shape, using spheres added with a Copy SOP, to get better framing. Later, to contrast with the solid aspect of the trail flower, I'll put a glass shader on these spheres to add something light and fragile.

步驟05：創(chuàng)建額外的詳細信息

對于這種類型的圖像，我喜歡玩弄形狀，紋理和材料的對比度。 我覺得我的構圖在這個階段有點簡單，所以決定生成一些粒子在我的主要形狀，使用添加了復制SOP的球體，以獲得更好的框架。 后來，為了與直線花的堅實方面形成對比，我將玻璃著色器放在這些球體上以增加輕微和脆弱的東西。

Step 06: Using Pyro FX

Now the fun part! Smoke! Since the beginning, I knew I wanted a dark, cloudy atmosphere for this image. To create these cloud shapes, I used Houdini's Pyro FX, which is a really powerful tool. With a little tuning, you can make something really cool with a lot of control over your shape. I have two emitters (standard sphere) with a lot of turbulence at emission. On my Pyro FX, I have a lot of swirl with a large amplitude to get those nice rounded shapes. Of course, I put a heavy density in my smoke, to get a really opaque aspect later in lighting.

步驟06：使用Pyro FX

現(xiàn)在有趣的部分！煙霧！ 從一開始，我知道我想要一個陰暗，多云的氣氛這個形象。 為了創(chuàng)建這些云形狀，我使用Houdini的Pyro FX，這是一個非常強大的工具。 有了一點調(diào)整，你可以做一些很酷的東西，很多的控制你的形狀。 我有兩個發(fā)射器（標準球體）在發(fā)射時有很多湍流。 在我的Pyro FX，我有很大的漩渦，大振幅，得到這些好的圓形。 當然，我把一個重的密度給我的煙霧，得到一個真正不透明的外觀。

Step 07: Shading and lighting

For the lighting, I used two kind of lights. First I set my environment with an HDRI map using the environment light tool. With that, I got an initial mood for the scene, ready to go further to adjust details. I added an area light on the top left to reveal a lot specular on my trails and spheres, and to get really good shadows in my smoke clouds.

For the shading, I used Mantra surfaces for every shader. I created a metallic one for the flower trail, with a little noise in Displacement and Roughness to obtain a really interesting render. As I mentioned earlier, I used a glass shader on the levitating spheres and finally a Billowy Smoke shader for the clouds with a colored ramp in the density attribute.

步驟07：陰影和照明

對于照明，我使用了兩種燈。 首先，我使用環(huán)境光工具使用HDRI地圖設置我的環(huán)境。 這樣，我得到了場景的初始情緒，準備進一步調(diào)整細節(jié)。 我在左上方添加了一個區(qū)域燈，在我的軌跡和球體上顯示了很多鏡面，并且在我的煙云中獲得了真正的陰影。

對于陰影，我為每個著色器使用Mantra表面。 我創(chuàng)造了一個金屬的花軌跡，在位移和粗糙有一點噪音，以獲得一個非常有趣的渲染。 正如我前面提到的，我在懸浮球上使用了一個玻璃著色器，最后一個Billowy Smoke著色器用于濃度屬性中的彩色斜坡。

Step 08: Compositing and post-work

Final step, compositing! For the background, I used a custom HDRi map, really blurred to give a cloudy sky feeling in the scene. I put a glow on the really bright specular and desaturated the overall image a little bit. With the depth of field, I got a lot of nice bokeh in the front. In combination with a little flare, I use God Rays on the smoke to give a final stormy effect. Playing with the contrast and the size of the depth of field, I adjust the final mood of my scene to get this stormy abstract effect.

步驟08：合成和后期工作

最后一步，合成！ 對于背景，我使用了一個自定義的HDRi地圖，真的模糊，給一個多云的天空的感覺在現(xiàn)場。 我把輝光放在真正明亮的鏡面上，使整個圖像失去了一點點。 隨著景深，我在前面有很多很好的散景。 結合一個小火光，我使用上帝的光線在煙霧，給最后的暴風雨的效果。 使用對比度和景深的大小，我調(diào)整我的場景的最終情緒，以獲得這種暴風雨的抽象效果。