Looking to do a proof of concept, and new to Kinect. I believe this is possible, but trying to gauge difficulty with links to tutorials etc explaining how this may work.
Looking to have the Kinect look at a walkway, and essentially detect people movement. This does not mean Skeletal movement, but essentially "foot traffic". I want to determine the noise of traffic, i.e. are there alot of people walking past, or a few. (Note this does not mean counting, just a rough indication. Can this be just pixel movement etc?)
Secondly, if a person then stops and faces the Kinect, pick them up as a user, and track rudimentary movements.
The second part I'm relatively comfortable with, the first I'm not.
Any help is appreciated is pointing me in the right direction. We are a Microsoft house, so any indication if Microsoft SDK, or OpenKinect is the best path would be great too.
How can I track fast hand movement using kinect?
I've tried both Openni and Microsoft sdk to track hand. On both of them, there are lots of jitters and inaccurate movement of joints.
Here is an example video of kinect fruit ninja: Example Video
On that video, there are no jitters and inaccuracy and also it's tracking the fast hand movements.
What am I missing? Is there any kinds of kinect hardware versions or types which I should look into.
My best guess is that Fruit Ninja applies some sort of smoothing at some point. What you're seeing in that video is almost certainly not the raw data they're getting from the Kinect. The data from the Kinect will always have some kind of jitter; real-world sensor data almost always does. You'll need to smooth it - exactly how to do that depends on the application; it could be something simple like modelling a kind of damping and/or inertia on the point that's being moved by the hand (which is what I suspect Fruit Ninja is doing), or you could look at something like a Kalman filter for a robust (but more computationally-intensive) way to reduce the noise in your sensor readings.
I'm wondering, does the Kinect detects joints correctly when it's put on the top (on the ceiling).
I don't have necessary equipment to attach it to ceiling and test, but was wondering whether it reliably detects human. I'm ok even if it confuses the joints, actually.
Has anybody tested this?
From what I've seen while using it, the skeleton detection is iffy from any angle other than directly pointing at a person's front or back. A Kinect pointed straight down with people walking under it would almost certainly not detect anyone, because the human form from above does not look anything like it does from the front. I have had the Kinect pick up random people around me in odd positions (sitting, viewed from the side, etc), but the joints were largely spastic. If you have it mounted on the ceiling and pointed downwards at a sufficient angle to still see people from the front instead of from above.. it could do a fairly good job of picking them up.
So when you say on the ceiling do you mean pointing straight down or still looking at a fairly horizontal angle?
I did a little bit of testing with the Kinect mounted in a very high position (2.5 m, 70° to the ground). As answered by Coeffect it just doesn't work. It doesn't work with Microsoft SDK nor with OpenNI. What I can add is that the skeleton recognition only works if the user is facing the camera with her/his whole body-front. Even worse, both frameworks seem to expect the head at the top of the depth-frame.
The definition of rigid body in Box2d is
A chunk of matter that is so strong
that the distance between any two bits
of matter on the chunk is completely
constant.
And this is exactly what i don't want as i would like to make 2D (maybe 3D eventually), elastic, deformable, breakable, and even sticky bodies.
What I'm hoping to get out of this community are resources that teach me the math behind how objects bend, break and interact. I don't care about the molecular or chemical properties of these objects, and often this is all I find when I try to search for how to calculate what a piece of wood, metal, rubber, goo, liquid, organic material, etc. might look like after a force is applied to it.
Also, I'm a very visual person, so diagrams and such are EXTREMELY HELPFUL for me.
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Ignore these questions, they're old, and I'm only keeping them here for contextual purposes
1.Are there any simple 2D soft-body physics engines out there like this?
preferably free or opensource?
2.If not would it be possible to make my own without spending years on it?
3.Could i use existing engines like bullet and box2d as a start and simply transform their code, or would this just lead to more problems later, considering my 1 year of programming experience and bullet being 3D?
4.Finally, if i were to transform another library, would it be the best change box2D's already 2d code, Bullet's already soft code, or mixing both's source code?
Thanks!
(1) Both Bullet and PhysX have support for deformable objects in some capacity. Bullet is open source and PhysX is free to use. They both have ports for windows, mac, linux and all the major consoles.
(2) You could hack something together if you really know what you are doing, and it might even work. However, there will probably be bugs unless you have a damn good understanding of how Box2D's sequential impulse constraint solver works and what types of measures are going to be necessary to keep your system stable. That said, there are many ways to get deformable objects working with minimal fuss within a game-like environment. The first option is to take a second (or higher) order approximation of the deformation. This lets you deal with deformations in much the same way as you deal with rigid motions, only now you have a few extra degrees of freedom. See for example the following paper:
http://www.matthiasmueller.info/publications/MeshlessDeformations_SIG05.pdf
A second method is pressure soft bodies, which basically model the body as a set of particles with some distance constraints and pressure forces. This is what both PhysX and Bullet do, and it is a pretty standard technique by now (for example, Gish used it):
http://citeseerx.ist.psu.edu%2Fviewdoc%2Fdownload%3Fdoi%3D10.1.1.4.2828%26rep%3Drep1%26type%3Dpdf
If you google around, you can find lots of tutorials on implementing it, but I can't vouch for their quality. Finally, there has been a more recent push to trying to do deformable objects the `right' way using realistic elastic models and finite element type approaches. This is still an area of active research, so it is not for the faint of heart. For example, you could look at any number of the papers in this year's SIGGRAPH proceedings:
http://kesen.realtimerendering.com/sig2011.html
(3) Probably not. Though there are certain 2D style games that can work with a 3D physics engine (for example top down type games) for special effects.
(4) Based on what I just said, you should probably know the answer by now. If you are the adventurous sort and got some time to kill and the will to learn, then I say go for it! Of course it will be hard at first, but like anything it gets easier over time. Plus, learning new stuff is lots of fun!
On the other hand, if you just want results now, then don't do it. It will take a lot of time, and you will probably fail (a lot). If you just want to make games, then stick to the existing libraries and build on whatever abstractions it provides you.
Quick and partial answer:
rigid body are easy to model due to their property (you can use physic tools, like "Torseur+ (link on french on wikipedia, english equivalent points to screw theory) to modelate forces applying at any point in your element.
in comparison, non-solid elements move from almost solid (think very hard rubber : it can move but is almost solid) to almost liquid (think very soft ruber, latex). Meaning that dynamical properties applying to that knd of objects are much complex and depend of the nature of the object
Take the example of a spring : it's easy to model independantly (f=k.x), but creating a generic tool able to model that specific case is a nightmare (especially if you think of corner cases : extension is not infinite, compression reaches a lower point, material is non linear...)
as far as I know, when dealing with "elastic" materials, people do their own modelisation for their own purpose (a generic one does not exist)
now the answers:
Probably not, not that I know at least
not easily, see previously why
Unless you got high level background in elastic materials, I fear it's gonna be painful
Hope this helped
Some specific cases such as deformable balls can be simulated pretty well using spring-joint bodies:
Here is an implementation example with cocos2d: http://2sa-studio.blogspot.com/2014/05/soft-bodies-with-cocos2d-v3.html
Depending on the complexity of the deformable objects that you need, you might be able to emulate them using box2d, constraining rigid bodies with joints or springs. I did it in the past using a box2d clone for xna (farseer) and it worked nicely. Hope this helps.
The physics of your question breaks down into two different topics:
Inelastic Collisions: The math here is easy, and you could write a pretty decent library yourself without too much work for 2D points/balls. (And with more work, you could learn the physics for extended bodies.)
Materials Bending and Breaking: This will be hard. In general, you will have to model many of the topics in Mechanical Engineering:
Continuum Mechanics
Structural Analysis
Failure Analysis
Stress Analysis
Strain Analysis
I am not being glib. Modeling the bending and breaking of materials is, in general, a very detailed and varied topic. It will take a long time. And the only way to succeed will be to understand the science well enough that you can make clever shortcuts in limiting the scope of the science you need to model in your game.
However, the other half of your problem (modeling Inelastic Collisions) is a much more achievable goal.
Good luck!
I want to get the pitch of a song at any point. I plan on storing the pitches later. How can I read say... an mp3 file or wav file to get the pitch played at a certain point?
Here is a visual example:
Say I wanted to get the pitch that is here at ^this point of the song.
Thanks if you can!
The matter is a tad more complicated than you may be anticipating.
While time-domain approaches exist (that is, approaches which work with the PCM data directly), frequency-domain pitch detection is going to be more accurate. You can read a very simplified overview here.
What you probably want is a Fourier Transform, which can be used to transform blocks of your signal from time-domain to frequency-domain (that is, a distribution of frequency content over a given span of the signal). From there, you would need to analyze the frequency spectrum within that block. The problem becomes even harder still, because there is no best way to deduce pitch from a sampled frequency spectrum in the general case. The aforementioned Wikipedia article should give you a foundation for looking into those algorithms.
Finally, it's worth noting that this is really a language-agnostic question, unless your primary interest is in reading a WAV file specifically using VB.NET.