I am making a sentry turret with servos and a paintball gun and need to implement real time motion tracing to make the gun shoot anything that moves. how can I code this(any good algorithms, books, tutorials)? I want to make it myself and not use premade solutions.
Lucas-Kanade with Kalman filtering is the bread and butter motion tracking algorithm. However, it's a bit outdated.
We (Success Labs) just published a Lucas-Kanade app for the iPhone. You can read about it here - http://www.success-ware.com/150842/Lucas-Kanade-Detection-for-the-iPhone
There's a link to the AppStore, and source code as well.
HTH,
Oded.
Related
I'm making an online billiard game. I've finished all the mechanics for single player, online account system, online inventory system etc. Everything's fine but I've gotten to the hardest part now, the multiplayer. I tried syncing the position of each ball every frame but the movement wasn't smooth at all, the balls would move back and forth and it looked "bad" in general. Does anyone have any solution for this ? How do other billiard games like the one in Miniclip do it, I'm honestly stuck here and frustrated as it took me a while to learn Photon networking then to find out it's not that good at handling the physics synchronization.
Would uNet be a better choice here ?
I appreciate any help you give me. Thank you!
This is done with PUN already: https://www.assetstore.unity3d.com/en/#!/content/15802
You can try to play with synchronization settings or implement custom OnPhotonSerializeView (see DemoSynchronization in PUN package). Make sure that physic simulation disabled on synchronized clients. See DemoBoxes for physics simulation sample.
Or, if balls can move along lines only, do not send all positions every frame. Send positions and velocities only when balls colliding and do simple velocity simulation between. This can work even with more comprehensive physics but general rule is the same: synchronize it at key points. Of course this is not as simple as automatic synchronization.
Also note that classic billiard is turnbased game and you do not have all the complexity of players interaction. In worst case you can 'record' simulation on current player client and 'playback' it on others.
I would like to implement in GameMaker exactly the same thing as in this article: http://www.redblobgames.com/articles/visibility/.
The code for it is available there in different languages, but I can't figure out how to effectively port it to GML. Every raycasting solution I tried leads to fps completely dying.
Could someone with more knowledge than me help ?
i have encountered this problem too, it mainly stems from the gamemakers execution speed.
check out the gm tech blog post on this here.
Also, this will probably work best as a shader as they run faster than object step events.
good luck!
BACKSTORY
The other day I found a motorized wheel chair that someone was throwing away. Being a maker who spends a lot of time looking at what other people have made online I decided to snatch it and try to make a robot out of it. I also bought an Arduino mega, a Kinect sensor, and a motor controller to try to control the motors and give it some form of vision.
MY VISION
Honestly I don’t intend for this robot to be much more than a fun, and challenging, project. My current goals are to have it run SLAM algorithms to figure out where it is on a map and for it to navigate to predetermined points on the map. However at this point I would be happy with just being able to do a simple teleop control with the keyboard.
MY PROBLEM
I have spent the past week researching ros and how to get it talking to my Arduino. I have installed diff_drive_controller, Turtlebot, ros_control, ros_serial, ros_arduino_bridge, and several others trying to find something that will tell the motors what to do. By now I feel like I have a good barely below the surface understanding about how ros works. Basically there are a series of nodes each publishing info for the other nodes to see and subscribing to info that they want to read. All I want right now is a node that publishes data about the velocity of the motors based on it trying to navigate or teleop or something like that. I think turtlebot is my best bet considering it is an all in one stack that does everything I want it to do. The only problem is I don’t have an iRobot create. But it seems like it should be simple enough to intercept those commands and have them drive my own robot base. However I’m not sure which topic to listen on and how to run turtle bot in a way that doesn’t try to connect to an iRobot create. I could just listen to the /cmd_vel_mux/input/teleop topic but I think that would limit me to just teleop and it might make it hard to move on to autonomy in the future.
What topic should I listen on? Am I going about this the right way? Are there any packages that would be better suited for my needs? Keep in mind that I am new to ros so tutorials would be appreciated.
I look forward to your responses
Thanks, Logan
Nice sounding project! I second the recommendation to take a look at the tutorials, but I think you spend some more time with the basic ROS tutorials before diving into the world of Arduino + ROS.
For instance, I noticed one misconception I believe you may have. It doesn't really matter which topic your nodes listens to, as its just a name that can be easily remapped through a parameter given when launching the node. The important thing is to ensure you are listening to the right type of messages - they specify the interface by which all the different nodes communicate. There's a bunch of options, and if none of them fit your use case, you can define your own.
I suspect that for low-level things, such as drivers for your motors, you will need to write your own ROS nodes. For advanced functionality, such as SLAM; there's a variety of options. You can find one that's suited to the input data you have available from your sensors.
One last recommendation is to take advantage of the features of ROS that allow you to break a big problem into manageable subtasks. Do one thing at a time - implement a motor contoroller, write a teleoperation method; taking care to specify suitable interfaces at each point. The advantage of this approach is that if you made smart choices in defining individual components with good interfaces, it is very easy to replace them with another one should you so wish.
You can find a list of tutorials how to interface Arduino and ROS here.
I'm new to this field - but I need to perform a WAV-to-MIDI conversion in java.
Is there a way to know what exactly are the steps involved in WAV-to-MIDI conversion?
I have a very rough idea as in you need to;
sample the wav file, filter it, use FFT for spectral analysis, feature extraction and then write the extracted features on to MIDI.
But I cannot find solid sources or papers as in how to do all that?
Can some one give me clues as in how and where to start?
Are there any Open Source APIs available for this WAV-to-MIDI conversion process?
Advance thanks
It's a more involved process than you might imagine.
This research problem is often referred to as music transcription: the act of converting a low-level representation of music (e.g., waveform) into a higher-level representation such as MIDI or even sheet music.
The sophistication of your solution will depend upon the complexity of your input data. Tons of research papers address music transcription only on monophonic piano or drums... because they are easy to transcribe. (Relatively.) Violin is harder. Voice is even harder. Violin plus voice plus piano is much harder. A symphony is nearly impossible. You get the picture.
The basic elements of music transcription involve any of the following overlapping areas:
(multi)pitch estimation
instrument recognition, timbral modeling
rhythm detection
note onset/offset detection
form/structure modeling
Search for papers on "music transcription" on Google Scholar or from the ISMIR proceedings: http://www.ismir.net. If you are more interested in one of the above subtopics, I can point you further. Good luck.
EDIT: That being said, there are existing solutions that we can all find on the web. Feel free to try them. But as you do, evaluate them with a critical eye and ear. What types of audio signals would cause transcription to fail?
EDIT 2: Ah, you are only doing this for piano. Okay, this is doable. Music transcription has advanced to the point where it can transcribe monophonic piano pretty well. A Rachmaninov concerto will still pose problems.
Our recommendations depend upon your end goal. You state "need to perform... in Java." So it sounds like you just want something to work regardless of how it gets you there. In that case, I agree 100% with others: use something that exists.
That's actually an interesting question; all of the MIR libraries I know are typically C/C++/Python/Matlab. But not Java. The EchoNest has a Java API, but I don't think it does note-level transcription. http://developer.echonest.com. (Edit: It does note-level transcription. The returned data includes pitch, timbre, beat, tatum, and more. But I find polyphony is still a problem.)
Oh, Marsyas is Java-based. Cool. I thought it was just C++. http://marsyas.info/ I recommend this. It's developed by George Tzanetakis, a professor in MIR. It does signal-level analysis and should be a good option.
Now, if this is for a fun learning experience, I think you can use the sound manipulation utilities in Java to experiment with the WAV signal and see what comes out.
EDIT: This page describes MIR software better than I can: The Tools We Use
For Matlab, you may be interested in the MIR Toolbox
Here is a nice page of common datasets: MIR Datasets
This is a very big undertaking for being new to the field, unless you mean you are familiar with signal analysis and feature detection in general and want to look more specifically into automatic transcription.
There is no API for WAV to MIDI conversion. Vamp is a framework for feature extraction plugins, but to do automatic transcription you would need to use all the functionality of the existing plugins, plus implement functionality that exists in none of them yet.
Browse through the descriptions of the plugins on the vamp download page, any descriptions you do not understand are topics you should start researching if you want to do this.
If you don't need to automate this task (ie, for a website where people can upload MP3's and get MIDI files back), then you should consider using a tool like Melodyne which is already quite good at going this. As Steve noted, this is a very difficult task to accomplish, and even the best algorithms and solutions present at the moment are not 100% reliable.
So if you are just doing studio work and need to do a few conversions, it will probably save you a bit of time (and lots of headache) to use a tool already designed for this task.
This is a field which is still highly under development, yet, there are some (experimental) algorithms available.
You can install sonic annotator and use a few vamp plugins.
For example:
./sonic-annotator file.wav -d vamp:qm-vamp-plugins:qm-transcription:transcription -w midi
./sonic-annotator file.wav -d vamp:silvet:silvet:notes -w midi
./sonic-annotator file.wav -d vamp:ua-vamp-plugins:mf0ua:mf0ua -w midi
Dolphin, sorry to be brusque, but you have completely underestimated the problem. What you want to achieve - a full piano sound transcription involving all parameters that were used while playing would need an enormous amount of research with people who have worked in the field for many years. Even a group of PhDs in signal processing would have to invest a lot of work to even come close to what you mean. Music transcription has needed decades of work to even work halfway reliable. I'd suggest you pick a different problem which you can manage better than this.
The studio I work at is currently developing the Tony Hawk XI website and I am responsible for the flash/AS3 development. As part of the pitch, I entered an augmented reality skateboard example to be shown which impressed the client very much.
After a few weeks of getting stronger with Papervision3D, and getting to know the Flar Toolkit, I have successfully imported md2 and dae files that load and interact with my custom marker.
Now it has come time to develop some of my own models; I will be using 3DSMAX. I want to know what the limitations are on things like poly-count, character rigging and animation, texturing, tricks for exporting and creating the proper format file and any other bits of information that may save me some serious headaches down the road.
Currently I have a Quake2 MD2 model, Ernie, pulled inside of a FlarToolkit demo here.
This is very low-poly and I was wondering how many polys could I expect to get away with being that today's machines are so much faster;
Brian Hodgeblog.hodgedev.com hodgedev.com
I've heard that 2000 polys is about the threshold for good performance. In practice though, its been hit or miss and a lot of things can have an impact. So far I've run into perfomance hits when using animated movieclip materials, animated materials with an alpha chanel and precise materieals.
Having to clip objects seems to be a double edged sword. In some cases, it will increase performance by a good deal, and in others (seems to be primarily when there are alot of polys on the edge of the viewport) it'll drop the framerate by a good 10-15 fps. So, I'd say the view you setup is something to think about as well.
For example, we have a model of an interior of a store with some shelves and products and customers walking around. In total we have just under 600 triangles (according to the StatsView, which you should check out if you haven't yet: org.papervision3d.view.stats.StatsView). On my computer, which is a new computer with a quad core it runs at a steady 30fps (which is where we want it), but on an old Dell XPS (Pentium 4) it runs between 20 and 30fps depending on what objects are being clipped, etc.
We try to reduce the poly count and texture creatively to fix as many of the performance issues as possible. Unfortunatley our minimum specs are really low, so we need to do alot to get it to run well.
Edit:
Another thing we're doing is swapping out less detailed models for higher detailed ones when zoomed in. If you aren't zooming at all, than this probably won't help.
Hope that helps a bit.