Phoenix FD Liquid Simulator不支援旋轉慣性

 

Phoenix FD Liquid Simulator有一個固定的流程，就是先設定好船的移動 (比方說從A移動到B)，然後把Liquid Simulator連結到那艘船。然後配合Motion Inertia這個選項讓液體模擬器帶有船的慣性。這樣一來你就不需要有超大的 涵蓋A到B的模擬範圍，你只需要大概在船身周圍大小的模擬器就可以了。節省了很多時間。

問題是，這個Motion Inertia並不會計算船的旋轉運動，沒辦法處理角速度，離心力或是Coriolis effects。因此這樣的操作不能用在當船轉彎的時候。

既然不能這樣做，唯一的解法是弄一個跨越A到B的，超大的simulator，但是這會讓模擬時間與檔案變得超大。

我不期待開發人員會把這個問題解決，回到我上一篇文章說的，如果一套軟體的功能是"works as advertised"如宣傳的那般好用，適用於各種實戰狀況，那軟體必然會轟動，使用者一定會愛用。Motion Inertia又是另一個例子。

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Excire Foto - Aesthetics 圖片的美學等級與參數自動化

Ocean shader and mesh 海洋製作材質筆記(二)

Phoenix FD 重置粒子的位置

產生asset跟單純算圖不同，asset會要求其pivot都是在(0, 0, 0)。畢竟希望給客戶乾淨的操作環境。

有時候在設置場景時，會經過好幾次的修改，Phoenix FD的Simulator可能就不在(0, 0, 0)的位置。如果你去修正 ，會發現Foam與Splash particles的位置仍然還在舊的pivot。

這時候要把先刪掉這兩個Particles，然後在Simulator裡面的Enable Foam，Enable Splash選項取消勾選，然後再次Enable，強制讓它更新pivot的位置。

我覺得這是無傷大雅的bug，只是需要手動更新一下。從另一個角度來看，一套軟體開發的過程，一定是把主功能，主架構寫出來，才會慢慢把這些實際操作時才會發現的小問題修掉。這倒不見得是程式設計師的錯，因為一開始很難關注到這些細枝末節。所以一般來說在大型studio在執行專案的時候不會輕易地更新軟體，畢竟你不知道新軟體，新版本是否帶了某些新的小bug。

也不是說追新軟體就一定是錯，早用早享受，但也要承擔風險。

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Phoenix FD with V-shape stern wake 船尾波的製作技巧

Conform modifier - collision proxy 快速產生碰撞體

在進行流體模擬時，使用的模型最好是封閉的(water-tight)的幾何體。但常常我們拿到的模型只是針對算圖好看，但卻很少是針對模擬所建模出來的，因此FX Artist必須花時間整理模型。

如果時間不夠的話這裡介紹一種快速方法 - Conform Modifier。

首先，先拉出一個能夠把鐵達尼號包起來的幾何體，以本例來說是Capsule

然後在Capsule上套用Conform Modifier，Method選Shrink Wrap，Direction選Closest point。這樣碰撞體就完成了，雖然不完美但是可以用在液體流體模擬上，簡單又快速。

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Maxscript: Select By Measuring 根據體積來選取物件

Phoenix FD with V-shape stern wake 船尾波的製作技巧

 

這篇要來分享一個之前有個客戶問的問題，就是遊艇後方的V-型波，或稱為stern wake。中文可以譯作船尾波。 一般船在航行時會產生兩個波，前方的叫做bow wave 船首波，後方叫船尾波。

預設的情況下，船首波很容易產生，把船的模型丟到場景裡，跑Phoenix FD Liquid sim，就自然會產生bow wave。要產生stern wake則需要多做一件事。

我們就不講背後的科學原理，直接講操作技巧。要在船後方螺旋槳的位置放一個box，然後從那個box噴出水。也就是說把那個box當成liquid source。

像這樣，因為這艘船是雙引擎，所以我放了兩個Box。選取那兩個面設置其face ID，使液體只從這兩個面噴出來。

這裡有個重點，就是那個box要稍微朝上，這樣液體射出時，會往上然後落下水面，會很自然地產生船尾波。

像這樣，就會產生你要的V-Shape stern wake。船尾波的形狀跟船速，船的大小還有船在水下的深度都有關係。

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Boat Wakes by McKellar Miscellany

D5 3.0 發表讓我對Chaos V-Ray近年來的發展更加失望

一直以來我都是推薦 V-Ray 以及 Chaos 相關的產品，但最近兩三年，Chaos 的表現卻每況愈下。看到 D5 Render 發表 3.0 版本的影片，只能嘆息一聲「恨鐵不成鋼」。

我知道 D5 Render是中國開發的軟體，因此我本身不會去使用，但就它的開發方向，我仍想談一點看法。很顯然，D5 Render 的許多功能都是針對建築視覺化所設計，強調直覺與方便，能夠非常快速地做出效果；相對之下，V-Ray 的功能層級更偏向底層，並非完全以建築為導向，因此在運用上更為靈活，能夠在非 AI 強化的情況下，透過細緻調整參數，逐步達到頂級擬真的算圖效果。

但 AI 已經改變了遊戲規則。很明顯，D5 已經開始侵蝕 V-Ray 原本稱霸的建築視覺化市場。過去的 D5 Render 還像是玩具一樣，只能產出「還算可用」的渲染圖；那麼 V-Ray 是否還能倚靠 VFX 市場站穩腳步？問題是，Chaos 有讓 Phoenix FD 這類特效相關軟體真正更加茁壯嗎？並沒有。原本可以成為 V-Ray 特色加分的功能，反而逐漸被邊緣化、被貶低。

再看近三年 Chaos 的開發方向：Chaos Envision 這套資產整合軟體（有點像獨立的 3D 軟體）、Chaos Arena 虛擬棚的即時渲染系統（坦白說，這和一般用戶幾乎沒有關係，誰家裡會有超大型螢幕來做虛擬攝影棚？），以及 Enscape 這套主打即時、快速的渲染軟體。這三個方向彼此之間幾乎沒有匯合感，Enscape 又在某種程度上與 V-Ray 形成競爭，而 Chaos Envision 與 Vantage 的定位也存在重疊。(好像漏掉了Corona)。整體來看，產品線繁多，但整合性卻相當差。問題是，客戶真的有錢到可以把你整條產品線一次買齊嗎？

Making realistic honey with Phoenix FD 蜂蜜流體特效

By Hammer Chen

In this article, I am going to share my tips & tricks for making realistic honey with Phoenix FD.

1. Modeling a honeycomb
Finding a photo-realistic model is very difficult. Even you have a budget to purchase from the online shop doesn't guaranty you get the right 3D model for the project. So I decided to model it by myself.

I found a handy tool from Scriptspot - Honeycomb, a maxscript by Anubis. This script allows you to generate a honeycomb shape with just one button.

Shading the Winter Explosion 冬季爆破特效

By Hammer Chen, Kristin Ivanova

We recently introduced the Artillery Explosion tutorial available in Phoenix FD’s documentation. Now, we want to show you a variation of this scene setup - a winter explosion with its proper shading.

This scene is essentially the same as the Artillery Explosion one, except for the smoke color and HDRI lighting. The smoke color is set to light gray in order to get a snowy look. To focus on the shading we also limit the number of bombs to just one.

Since there is a hot explosion at the core, it could make the rendering over-exposed or lose detail in the white smoke volumetric shading.

The good news is Phoenix FD provides a cohort of parameters allowing you to fine-tune the shading. Here we compare some of the useful settings that deal with this issue.

Overall Setup
The scene we use here is modified from the Artillery Explosion scene, except we add one Phoenix FD Turbulence helper and change the color of the smoke. For a step-by-step tutorial of how the Fire / Smoke sources and thinkingParticles are set up, please check out the Artillery Explosion tutorial.

Whitewater shading with Phoenix FD 白水效果

By Hammer Chen

Whitewater is formed in a rapid, when a river's gradient increases enough to generate so much turbulence that air is entrained into the water body, that is, it forms a bubbly or aerated and unstable current; the frothy water appears white. --- Wikipedia

In this article, I am going to show you how to set up whitewater shading with Phoenix FD.

To set up a scene for whitewater shading you will need:

1. A Phoenix FD Liquid Simulator - for simulation of liquid and generate "Vorticity smooth" data
2. A Phoenix FD Fire/Smoke Simulator - this is not for simulation. This Fire/Smoke Simulator doesn't have to be high resolution, because it purely functions as a container to load up "Vorticity smooth" data from Liquid Simulator, and shading / rendering them as smoke.
3. LiquidSrc

Large Scale Fire with Phoenix FD 大尺度火焰特效

 

By Hammer Chen, Kristin Ivanova

In the previous post, we saw how to create a small-scale fire. In this article we are talking about large-scale fires. A large-scale fire can be a ground fire, a wooden house on fire, or maybe fire in an explosion. Let's explore how to create realistic large-scale fire with Phoenix FD.

Fire is very tricky to make in CG. In the previous article, we have introduced the VRayDistanceTex to alleviate artifacts at the fire root. That is, by using a VRayDistance texture to modulate the fire opacity. In this article, we are going to give more tips & tricks for creating convincing fire.

First of all, let's talk about how the fire is emitted. Take a ground fire for example, we can use a simple plane (with shell modifier on top) and vertex paint to mask the fluid source. To avoid getting one big chunk of fire, paint the vertex color with smaller areas. This way we can create a more natural form of the flame.

Secondly, Phoenix FD Turbulence has a great effect on the overall motion of fire. For example, below we compare the dynamics of a flame without Phoenix FD Turbulence and with Phoenix FD Turbulence. See how the flame looks dull without Turbulence.

Making of Lava Flow with TexUVW 岩漿特效

 

By Hammer Chen, Kristin Ivanova

Phoenix FD 4's new feature TexUVW opens a great opportunity for adding details to your fluids. It allows fluids to transport UVW information along with the moving fluid. You can find an example in the "Using TexUVW for Creating Thin Smoke" tutorial, available on the Phoenix FD official page. In the tutorial, smoke opacity is masked with a noise texture, with the help of TexUVW, to enhance the details that mimic thin smoke. 

In this article, we are taking advantage of this new feature in order to create a lava flow. The folding character of the lava is generated through bump maps and displacement.

References

When creating a lava stream, we need to consider what type of lava we want to use for reference. A variety of lava types exist depending on terrain, speed, hotness, and material composition. For the purpose of this article, we will create a "pahoehoe"  (pronounced 'paw-hoey-hoey") type of lava (see the reference images above), which creates folds as it moves. However, if you intend to simulate molten lava, you can check the "Solidifying of Molten Lava" tutorial on the official documentation site.

Making of Deer Crossing River 麋鹿渡河特效

By Hammer Chen

In this article, I am going to share some tips & tricks of how I made this deer crossing river animation. Although it might look daunting at first glance, the settings for Phoenix are quite simple. The most critical thing for making this animation is the hardware.

As you can see, the total cache size for the whole animation (250 frames) is around 535 GB. So you better have a faster RAM and a hard drive with enough space for this kind of project. Once you have your hardware ready, leave it to Phoenix, Don't worry, Phoenix FD does support large-scale fluids like this one.

The image above shows my scene setup. The herd of deer is generated from a single rigged deer, duplicated by using thinkingParticles. There is no animation variation of the deer character, so the setting is simple, only offsetting animation for each deer.

VRayVolumeGrid and Nuclear Explosion 核爆整合

By Hammer Chen

In this article I am going to show you the benefit of using Phoenix FD in tandem with VRayVolumeGrid. I will use a nuclear explosion as an example.

Phoenix FD is capable of simulating complex explosions, such as air strike, small or large scale explosion. For a realistic blast, it always involves many different components. For example, the nuclear explosion you have a major mushroom cloud that flies into the sky; and the ground dust triggered by the mushroom cloud explosion. With multiple fire/smoke sources, Phoenix FD can perform realistic nuclear explosion simulation. In fact, you can find a downloadable nuclear explosion scene on the ChaosGroup official sample page.

With that said, what if you want extra degree of freedoms for tweaking and shaping the extract nuke you want. Simulating each component separately might be a way to go. I'll explain why.

A collection of reference images from the Internet

Let’s take a look at physical reality. A nuclear bomb was placed on the ground, somewhere in an unknown desert. When the bomb blast off, initiate the chain reaction, heat climbing and generate lots of smoke as a by-product the chemical reaction; that major explosion pushes the ground dust which is already there before the blast. We can say the physical properties of those two elements (the ground dust and explosive mushroom) are no doubt different things.

Bullet Time with Phoenix FD 子彈時間慢動作特效

By Hammer Chen

Have you ever wondered how to create a bullet-time effect for liquids with Phoenix FD? Especially when working with rigid body simulation? The answer is surprisingly simple: animate the Phoenix FD's "Time Scale" parameter. In this article, I am going to show you the workflow.

1. Scene Setup

We have two wine glasses in the scene  and a sphere flying from right to left, that hits and breaks the glasses. You can use any package to simulate the rigid body dynamics, for example,  PFlow mParticles or RayFire. In this case, I use thinkingParticles.

Visualize your forces with Force Preview 視覺化力場

by Hammer Chen

When dealing with complex scene, sometimes you have to adjust forces in the scene back and forth to get the desired results. You have to change parameters, run the sim, render preview and change parameters again.

For creating ocean maelstrom, adding a vortex force might be a quick answer. However, finding the right parameters could be a nightmare for you. If the orbital speed too high, or it's falloff too short. Or if there is not enough radial pull. You might not be able to get the right maelstrom.

With new Force Preview, you can see how Phoenix or standard 3ds Max forces will influence the simulation — without multiple iterations

Making of a Burning Motorcycle 燃燒的摩托車

By Hammer Chen

In this article, I am going to show you some of the critical steps of making this burning motorcycle image with Phoenix FD.

The model was kindly provided by Lien Ying-Te. Though this is a sub-D model, there are a lot of parts and faces in the geometry. The first thing I do is attach all the pieces into one single mesh, and then use ProOptimizer to reduce the polyfaces to roughly 10% of its original polycounts. You get a significant simulation performance increase when you have fewer polycounts as a fire/smoke source.

Making clouds with Phoenix FD 雲朵模擬教學

by Hammer Chen

Do you know you can create realistic cloud by simply budding off smoke from a single plane? The key is using the right mask and scattering setting.

Here we have one 3dsMax plane primitive as Fire / Smoke source. (Please note that Phoenix FD doesn't like non-closed geometry. If you having any trouble emitting fluid from a plane, add a shell modifier to the plane can fix the issue)

Phoenix FD: Pure Ocean mode 純海洋模式

This small handy feature allows you to preview ocean mesh without any simulations. The video was recorded by Svetlin Nikolov.

Surface condensation with Phoenix FD 表面張力水珠

by Hammer Chen

(Click Here to download the sample scene for max 2015)

Do you know you can create photo realistic surface condensation with Phoenix FD? The key is using a procedural texture map - Stucco as a mask for the LiquidSrc.

You could also animate the texture map (i.e., Z offset in this example), with the right timing you could get waterdrop sliding over the fruit surface.

Surface Tension is another key to simulate realistic droplet. The Droplet Breakup parameter controls the balances between the liquid forming tendrils or droplets. For more detail, you could visit Phoenix FD official help page.

Image-based colored smoke 用貼圖控制煙霧顏色

by Hammer Chen

Creating an image-based colored smoke is pretty straightforward with Phoenix FD. Here are three key steps you need to know:

1. Output RGB channel
Check RGB checkbox in the output section

Fluid color mixing with Phoenix FD 牛奶巧克力混色教學

by Hammer Chen

Phoenix FD allows you to mix the liquid with different RGB color, chocolate, and milk for example. Here are few steps you can follow:

1. Out Grid RGB Channel

2. Set two of your LiquidSrc with different RGB color. In this particular example, I set my milk LiquidSrc with black RGB color and white for chocolate.