Somebody know fluid engine for iphone?I need water and gases simulation.
Simulating fluids is a tremendous challenge for modern desktop computers, so I would not expect the greatest performance when trying to get this working on a mobile device. Running full Navier-Stokes calculations on the iPhone is probably going to chug pretty badly.
However, in the past I was able to perform 2-D fluid modeling simulations on limited hardware using lattice gas automata. With lattice gas automata, you approximate a fluid as a fine hexagonal grid, where particles can travel in one of six directions and obey specific collision rules. There are some limitations to this approach (addressed by the Lattice Boltzmann Method), but it can do a very good job of simulating fluids, even including compressible ones like air. Why this works well on limited hardware is that these calculations can be done using bitwise operators and simple lookup tables, without the need for any floating point calculations. You might be able to make something like this work on the iPhone's processor. For more on this technique, you can consult Appendix A of my Ph.D. dissertation, where I explain the process and have source code for a fluid modeler I wrote.
That said, if all you want to do is mimic the appearance of water in your application, the answers to the following questions provide some good suggestions:
"How to implement water ripples?"
"How do I make a water effect view with openGLES on the iPhone?"
I have just released an iPhone fluid simulator that uses a compressible particle in cell method. I have a video here: http://www.youtube.com/watch?v=-CCeeh8EzuA
An incompressible fluid simulator requires many iterations, so I use a compressible simulator. The good thing is if you can make a compressible simulator stable enough, it usually looks incompressible enough.
My app is called GFlow on the app store if you want to see it in action.
I have release two iPhone apps. One app solves the Navier Stokes equations:
http://itunes.apple.com/us/app/fluid-dynamics/id382274493?mt=8
and the other one uses a compressible particle in cell method:
http://itunes.apple.com/us/app/liquid-dynamics/id417814216?mt=8&ls=1
A description of the methods used is founde here:
http://www.infi.nl/blog/view/id/71/Navier_Stokes_iPhone_vs_iPad
and here:
http://www.infi.nl/blog/view/id/98/Liquid_on_iPhone_and_iPad
Related
I am a mathematician and not a programmer, I have a notion on the basics of programming and am a quite advanced power-user both in linux and windows.
I know some C and some python but nothing much.
I would like to make an overlay so that when I start a game it can get info about amd and nvidia GPUs like frame time and FPS because I am quite certain the current system benchmarks use to compare two GPUs is flawed because small instances and scenes that bump up the FPS momentarily (but are totally irrelevant in terms of user experience) result in a higher average FPS number and mislead the market either unintentionally or intentionally (for example, I cant remember the name of the game probably COD there was a highly tessellated entity on the map that wasnt even visible to the player which lead AMD GPUs to seemingly under perform when roaming though that area leading to lower average FPS count)
I have an idea on how to calculate GPU performance in theory but I dont know how to harvest the data from the GPU, Could you refer me to api manuals or references to help me making such an overlay possible?
I would like to study as little as possible (by that I mean I would like to learn what I absolutely have to learn in order to get the job done I dont intent to become a coder).
I thank you in advance.
It is generally what the Vulkan Layer system is for, which allows to intercept API commands and inject your own. But it is nontrivial to code it yourself. Here are some pre-existing open-source options for you:
To get to timing info and draw your custom overlay you can use (and modify) a tool like OCAT. It supports Direct3D 11, Direct3D 12, and Vulkan apps.
To just get the timing (and other interesting info) as CSV you can use a command-line tool like PresentMon. Should work in D3D, and I have been using it with Vulkan apps too and it seems to accept them.
I am working on a crowd controlled soundsystem for a music festival. Music would be controlled by individuals and the crowd as a whole, more or less 500 people.
While searching for crowd tracking techniques, I stumbled upon this one http://www.mikelrodriguez.com/crowd-analysis/#density; Matlab code and dataset are enclosed. Are you aware of similar techniques, maybe simpler, based eg on blob detection? Do you have an idea about how well this one would perform in a real-time scenario? Is there a known way to do this with eg OpenCV?
One of my former colleagues implemented something similar (controlling a few motors according to crowd movement) using optical flow. You can analyze the frames of video from a camera, calculate optical flow between frames, and use the values to estimate the crowd movement.
OpenCV has support to perform the above tasks, and comes with good code samples. A desktop should be able to do this in real-time (you might have to tweak with image resolution).
I am not exactly sure how to interface between a C++ program and a sound system. Pure Data (PD) is an alternative, but it might not have much support for motion analysis.
I am starting an AR project for a client which involves using AR in order to show information about certain objects. In this project, for example, the user would point the camera at a car. Depending on which part of the car the user is looking at (headlights, windshield) a button would appear. When the user presses that button, an information window would appear on screen, giving the user more information about that certain car part.
The client doesn't wish to place physical markers on the car (QR code / patterns), and so the car parts would have to be detected another way.
I have developed AR apps before, but based on user location and generated markers in the sky. I feel this system wouldn't be entirely relevant for the client's request.
Would anybody be able to point me in the right direction (iOS library) for this sort of project, and whether or not it would be entirely feasible.
Thanks for the input,
Andy.
What you need is a model-based tracker/6DOF object tracker. As you want to track a car, it will certainly be featureless (or you will only get sparse features), so you should look at textureless non planar 3D (object) tracking solutions.
It's pretty much state of the art right now (lot of research, few products/SDK), but using library like OpenCV and with the appropriate literature (see below) you should be able to develop one. You can look at an open-source solution like the ViSP library which has a module for model based tracker but not an official iOS port. for commercial libraries, closest will be AR libraries supporting SLAM or "3D object tracking".
In term of techniques, you have different way to handle this problem, some pointers:
You can use a model-based tracker relying on edge detection + initial CAD model of the object: 3D Textureless Object Detection and Tracking: An Edge-based Approach or Harald Wuest, Folker Wientapper, Didier Stricker Adaptable Model-based Tracking Using Analysis-by-Synthesis Techniques
The 12th International Computer Analysis of Images and Patterns (CAIP), 27-29th August 2007, Vienna, Austria.
You can use a model-based tracker relying on edge detection + (trained) template images
You can use some SLAM techniques combined with a model based tracker.
M. Tamaazousti, V. Gay-Bellile, S. Naudet Collette, S. Bourgeois, M. Dhome Real-Time Accurate Localization in a Partially Known Environment:Application to Augmented Reality on textureless 3D Objects. TrakMark 2011, Basel, Switzerland 26-29/10/2011
if your system will only run indoor, you can look at some RGBD tracker
S. Hinterstoisser, V. Lepetit, S. Ilic, S. Holzer, G. Bradski, K. Konolige, N. Navab
Model Based Training, Detection and Pose Estimation of Texture-Less 3D Objects in Heavily Cluttered Scenes Asian Conference on Computer Vision (ACCV), Korea, Daejeon, November 2012
(access to the software)
It seems you are heading for an interesting topic. However, my concern is the accuracy of what you are trying to do. Location-based AR would be a starting point for your research work. Still the granularity would be less to your problem domain. Since you have worked on the location-based AR application, you might have noticed the accuracy that you can expect would be maximum upto 3 meters. Therefore, that level of accuracy cannot address your problem domain in an advanced way.
However, I have seen prototypes that addresses your problem domain. One good example would be the BMW Augmented Reality Manual. Check this link http://www.youtube.com/watch?v=P9KPJlA5yds
Hence, I never came across a proper Augmented Reality library for iOS or even Android which can address your problem domain in the marker-less AR context.
The information above is only for your knowledge, but not to discourage you in any way.
For a while I've been attempting to simulate flowing water with algorithms I've scavenged from "Real-Time Fluid Dynamics for Games". The trouble is I don't seem to get out water-like behavior with those algorithms.
Myself I guess I'm doing something wrong and that those algorithms aren't all suitable for water-like fluids.
What am I doing wrong with these algorithms? Are these algorithms correct at all?
I have the associated project in bitbucket repository. (requires gletools and newest pyglet to run)
Voxel-based solutions are fine for simulating liquids, and are frequently used in film.
Ron Fedkiw's website gives some academic examples - all of the ones there are based on a grid. That code underpins many of the simulations used by Pixar and ILM.
A good source is also Robert Bridson's Fluid Simulation course notes from SIGGRAPH and his website. He has a book "Fluid Simulation for Computer Graphics" that goes through developing a liquid simulator in detail.
The most specific answer I can give to your question is that Stam's real-time fluids for games is focused on smoke, ie. where there isn't a boundary between the fluid (water), and an external air region. Basically smoke and liquids use the same underlying mechanism, but for liquid you also need to track the position of the liquid surface, and apply appropriate boundary conditions on the surface.
Cem Yuksel presented a fantastic talk about his Wave Particles at SIGGRAPH 2007. They give a very realistic effect for quite a low cost. He was even able to simulate interaction with rigid bodies like boxes and boats. Another interesting aspect is that the boat motion isn't scripted, it's simulated via the propeller's interaction with the fluid.
(source: cemyuksel.com)
At the conference he said he was planning to release the source code, but I haven't seen anything yet. His website contains the full paper and the videos he showed at the conference.
Edit: Just saw your comment about wanting to simulate flowing liquids rather than rippling pools. This wouldn't be suitable for that, but I'll leave it here in case someone else finds it useful.
What type of water are you trying to simulate? Pools of water that ripple, or flowing liquids?
I don't think I've ever seen flowing water ever, except in rendered movies. Rippling water is fairly easy to do, this site usually crops up in this type of question.
Yeah, this type of voxel based solution only really work if your liquid is confined to very discrete and static boundaries.
For simulating flowing liquid, do some investigation into particles. Quite alot of progress has been made recently accelerating them on the GPU, and you can get some stunning results.
Take a look at, http://nzone.com/object/nzone_cascades_home.html as a great example of what can be achieved.
I would like to make a list of remarkable robot simulation environments including advantages and disadvantages of them. Some examples I know of are Webots and Player/Stage.
ROS will visualize your robot and any data you've recorded from it.
Packages to check out would rviz and nav_view
This made me remember the breve project.
breve is a free, open-source software package which makes it easy to build 3D simulations of multi-agent systems and artificial life.
There is also a wikipage listing Robotics simulators
Microsoft Robotics Studio/Microsoft Robotics Developer Studio 2008
Also read this article on MSDN Magazine
It all depends on what you want to do with the simulation.
I do legged robot simulation, I am coming from a perspective that is different than mobile robotics, but...
If you are interested in dynamics, then the one of the oldest but most difficult to use is sd/fast. The company that originally made it was acquired by a large cad outfit.
You might try heading to : http://www.sdfast.com/
It will cost you a bit of money, but I trust the accuracy of the simulation. There is no contact or collision model, so you have to roll you own. I have used it to simulate bipeds, swimming fish, etc.. There is also no visualization. So, it is for the hardcore programmer. However, it is well respected among us old folk.
OpenDynamics engine is used by people http://www.ode.org/ for "easier" simulation. It comes with an integrator and a primitive visualization package. There are python binding (Hurray for python!).
The build in friction model.. is ... well not very well documented. And did not make sense. Also, the simulations can suddenly "fly apart" for no apparent reason. The simulations may or may not be accurate.
Now, MapleSoft (in beautiful Waterloo Canada) has come out with maplesim. It will set you back a bit of money but here is what I like about it:
It goes beyond just robotics. You can virtually anything. I am sure you can simulate the suspension system on a car, gears, engines... I think it even interfaces with electrical circuit simulation. So, if you are building a high performance product, than MapleSim is a strong contender. Goto www.maplesoft.com and search for it.
They are pretty nice about giving you an eval copy for 30 days.
Of course, you can go home brew. You can solve the Lagrange-Euler equations of motion for most simple robots using a symbolic computation program like maple or mathematica.
EDIT: Have not be able to elegantly do certain derivatives in Maple. I have to resort to a hack.
However, be aware of speed issue.
Finally for more biologically motivated work, you might want to look at opensim (not to be confused with OpenSimulator).
EDIT: OpenSim shares a team member with SD/Fast.
There a lots of other specialized simulators. But, beware.
In sum here are the evaluation criteria for a simulator for robot oriented work:
(1) What kind of collision model do you have ? If it is a very stiff elastic collision, you may have problem in numerical stability during collisions
(2) Visualization- Can you add different terrains, etc..
(3) Handy graphical building tools so you don't have to code then see-what-you-get.
Handling complex system (say a full scale humanoid) is hard to think about in your head.
(4) What is the complexity of the underlying simulation algorithm. If it is O(N) then that is great. But it could be O(N^4) as would be the case for a straight Lagrange-Euler derivation... then your system just will not scale no matter how fast your machine.
(5) How accurate is it and do you care?
(6) Does it help you integrate sensors. For mobile robots you need to have a "robot-eyes view"
(7) If it does visualization, can it you do things like automatically follow the object as it is moving or do you have to chase it around?
Hope that helps!
It's not as impressive looking as Webots, but RobotBasic is free, easy to learn, and useful for prototyping simple robot movement algorithms. You can also program a BasicStamp from the IDE.
I've been programming against SimSpark. It's the open-source simulation engine behind the RoboCup 3D Simulated Soccer League.
It's extensible for different simulations. You can plug in your own sensors, actuators and models using C++, Ruby and/or RSG (Ruby Scene Graph) files.
ABB has a quite a solution called RobotStudio for simulating their huge industrial robots. I don't think it's free and I don't guess you'll get much fun out of it but it's quite impressive. Here's a page about it
I have been working with Carmen http://carmen.sourceforge.net/ and find it useful.
One of the disadvantages with Carmen is the documentation with all respect I think the webpage is a bit outdated and insufficient. So I like to hear from other people with experience in working with Carmen, or student reports/projects dealing with Carmen.
You can find a great list with simulation environments http://www.intorobotics.com/robotics-simulation-softwares-with-3d-modeling-and-programming-support/
MRDS is one of the best and it's free. Also LabView is good to be used in robotcs
National Instruments' LabView is a graphical programming environment for developing measurement, test, and control systems.
It could be used for 3D control simulation with SolidWorks.
MRDS is free and is one of the best simulation environment for robotics. Workspace also can be used, and please check this link if you want a complete list with robotics simulation software
Trik Studio has a nice and clear 2D model simulator and also visual and textual programming programming environments for them. They also soon will support 3D modeling tools based on Morse simulator. Also it is free and opensource and has multi-language interface.