Bullet Open Source Physics Engine Several of the top visual effects studios and game developers are now adopting the Bullet open source physics engine for collision detection and rigid body dynamics work. We talk exclusively to Bullet’s main author Erwin Coumans about the current implementation of the physics engine and its future development. Bullet has certainly been used in some recent high profile films by major visual effects studios, who, says Coumans, often customize the code with their own in-house work and combine it with pre-fracturing tools. The physics engine was adapted by Digital Domain for the studio’s Los Angeles destruction effects in 2012, and by Framestore in its in-house fBounce tool for Sherlock Holmes. Bullet was used in 2012 Bullet is open source According to Coumans, the significant adoption rate comes down to the fact that the cross-platform Bullet library is open source under the permissive ZLib license, unlike proprietary libraries such as Havok and PhysX. Thanks so much for reading our article.
The Science of Fluid Sims Fluid sims have become such a vital part of so many visual effects films, yet are not well understood by most general artists. We try and explain the science behind the fluid sims, and look at one in particular closely: Naiad, with help from our friends at Exotic Matter. Introduction One of the most significant and commonly requested areas of real world simulation is fluid simulation. From pouring shots to ocean vistas, directors and artists have come to rely on computer simulated water and similar fluids. Fluid sims are not confined to just fluids either, they can be used to achieve fire and flames - the fluid being simulated in this scenario is the air itself (a gas). Fluid simulations (fluid sims) have many applications outside visual effects. History Before the computer graphics industry got involved, fluids simulation was being actively modeled mathematically as early as the 1950's and 60's. - Watch Jerry Tessendorf talk at TED. - A Naiad scene test: 'Bunny in Trouble' Basic concepts
Science of Fluid Sims: Pt 2 – RealFlow Last September we published a piece on fluid sims. The aim was to examine the topic via one primary approach. Here is a second companion piece to that original story that examines the topic via the work of Fusion CI Studios. Mark Stasiuk and Lauren Millar are co-founders of Fusion CI Studios, a dynamic effects specialist facility that uses RealFlow extensively. Millar is a filmmaker of 20 years’ experience, having produced or directed more than 75 TV shows, and Stasiuk holds a PhD in geophysical fluid mechanics. Stasiuk started using RealFlow and answering questions on the forums with such insight that RealFlow’s authors at Next Limit began noticing. - Above: watch Fusion CI’s demo reel. Stasiuk has a doctorate from Bristol University in fluid dynamics of volcanic eruptions. “We called him Dr. In the end, Stasiuk decided that RealFlow was more interesting than the managerial role he had found himself promoted into with volcanic observatories and government work. RealFlow Polygonization
2012: Disaster Porn To bring general world-ending mayhem to his latest disaster film, 2012, director Roland Emmerich relied on a contigent of effects vendors under the supervision of Volker Engel and Marc Weigert. In this article, we focus on the work of two of those vendors: Digital Domain and Sony Pictures Imageworks. In this week’s fxpodcast, we discuss Double Negative’s work on the film. Podcast In this week’s fxpodcast we speak to Alex Wuttke, (Quantum of Solace, 10,000 BC, Batman Begins ) visual effects supervisor at Double Negative (DNeg), about the two main sequences of 2012 completed at DNeg in London. Escape from LA (by plane) One of the major disaster sequences in 2012 features struggling author Jackson Curtis (John Cusack) and his entourage flying through a destructive Los Angeles earthquake. Effects supervisor David Stephens managed the development of a new shattering pipeline and rigid body dynamics tool based on Bullet, which became known as Drop. Voronoi Diagram How to build an ark
Tutorials | A Pile Of Grains This post will try to explain how to write and install your own VEX DSO plugin for Houdini, written in C++. The included example project creates a plugin called VexImageReader. This plugin can be used to read all sorts of images, including psd and dds files. The function takes as input arguments a U and V coordinate, an input string (image name) and a wrap mode. Before we start, download the necessary files right HERE. The source code and Visual Studio 2008 project file (code)The FreeImage library source code (freeimage/Source)A compiled x64 windows DSO (build)A compiled x64 windows FreeImage library (freeimage/Dist)An otl that wraps the Vex function call in to a VOP (otl)An example HIP file (hipfile)The VEXdso include file, used by Houdini to add the VEX plugin to the houdini DSO table. As mentioned above, I included the compiled plugin. The code should be cross-platform compatible. Notes on compiling the VexImageReader DSO Loading the VEX DSO in Houdini Wrapping the function in an OTL
Level set method Video of spiral being propagated by level sets (mean curvature flow) in 2D. LHS shows zero-level solution. RHS shows the level-set scalar field. The level set method (LSM) is a numerical technique for tracking interfaces and shapes. Level set method[edit] An illustration of the level set method The figure on the right illustrates several important ideas about the level set method. determining this shape, and the flat blue region represents the xy-plane. , while the shape itself is the set of points in the plane for which is positive (interior of the shape) or zero (at the boundary). In the top row we see the shape changing its topology by splitting in two. Thus, in two dimensions, the level set method amounts to representing a closed curve (such as the shape boundary in our example) using an auxiliary function , called the level set function. is represented as the zero level set of by and the level set method manipulates implicitly, through the function . and negative values outside.[2][3] Here,
High Resolution Explosion - od[forum] - Page 1.3 'MENOZ', on 28 Feb 2011 - 5:30 PM, said: very cool example!but I don't understand the use of the vorticles. I thought that they are generated inside the smoke solver, so I don't understand why you added them. I'm missing something.just for clarity: vorticles are points used to add detail and "vorticity" to the simulation, and the "vortex confinement" parameter in the smoke solver adjust how much vortex force is transferred from those points. Although they have a similar purpose you are mixing two different elements here:The goal: introduce extra swirl:1) vorticity confinement: compensate for potentially lost swirl due to rounding/averaging of your velocity. 2) vorticles: "artificial" or artistic influence objects. -> makes much more sense to me to do it like in Julien's file.
power of gas repeat solver 'JuriBryan', on 28 Mar 2012 - 08:42 AM, said: hey I am quite new to customizing all my Dops in such a way... so I was wondering over a few things...First and for all... how do you keep the nice looking shape in your fire with the repeat solver in the network?when ever I want to use it all i get is a big ball and thats it. but you still got swirl and everything in the shape and no matter what I do i never get something that looks even close to ok.And my second question would be, how to you break geo with fluid effects?I went over your scene file a hundred times and I thought that I found out how(enabling the "collision from velocity field" function in the pyro object)but its never breaking the geo....got any tips for me... I am really lost:)thanksJuri RBD has been pushed by to use "feedback scale" parameters in pyro solver.
Small Wall Explosion I have always tried to create my effects w some variation of POPs, so I decided it was finally time to sit down and learn smoke. To do that Ive been trying to put together a personal project of a hole blowing out of a wall in the parking lot of my building. Sooo heres my progress so far. would love to hear feedback, good bad, or ugly. most current video(10/5/11): View on Vimeo. View on Vimeo. the next tests were of the wall exploding alone, this render is in 3D, but you can turn off the 3D in the bottom right of the player here this is the first test using smoke and a wind force + impulse force and in this render im trying to use multiple smoke sims w metaballs and magnet forces. also, im using the feedback from the internal smoke explosion to help drive the fracture in the wall
RBD activation (.hipnc for testing included) I've been using this solution I found..i think it was here on odforce. Where you could animated a bounding box, and activate physics bodies based on alot of attribute color management in a ForEach SOP. However I noticed that when you come up to 2-300 pieces and above the ForEach SOP doing this slows down your sim alot. So I did this dirty little solution, it also uses a ForEach SOP, but alot less attribute managment inside, it uses a VOP_SOP. so it's rather fast. It probably can "missfire" if you have groups of pieces that are not connected. and you may want to tweak the settings some if you have strange mesh. I included a .hipnc if you want to test it out, there are two geo's in /obj, 1 is the solution I used before, and the other is the VOP_SOP solution. Maybe something like this already is out there, or a better solution, just thought I'd share what was a big speed increase and worked for me, hope you like it. View on Vimeo.
Voronoi - dynamic - location based fracture (WIP) - od[forum] - Page 1.6 Mario Marengo, on May 22 2009, 02:05 PM, said: Someone's having way too much fun around here. Heh, yeah I think I went a little fanboy there when I realized how easy it was to implement explosions. Chasing down all the external references in my assets and replacing them with 100-character stamp expressions has temporarily cured me of that. anamous, on May 22 2009, 02:06 PM, said: i've been trying to stay off this thread because i can't stand the tingling feeling of being teased... but i have to say that this is some of the most impressive demonstration of what this software is all about - it's looking great, and i can't wait to see where you're gonna take it next. ingenious.cheers,Abdelkareem Thanks a lot, Abdelkareem, I appreciate it. Ratman, on May 22 2009, 02:16 PM, said: Have you done any kind of stress test of this that you can post? Well, it depends on whether you're talking about pre-fractured or dynamically fractured.