What is the best method to track/recognize an object using a Kinect and Java or C programming after having a constant track on the object in 3D space I wanted to have the coordinates.
I know the exact object I wanna tack and wanted to the most convenient way to track the object.
I've currently programming with processing using Java, I'm a newbie to this any help would be appreciated.
Stack Overflow isn't really designed for general "how do I do this" type questions. It's designed for more specific "I tried X, expected Y, but got Z instead" type questions. That being said, I'll try to help in a general sense:
Break your problem down into smaller pieces.
Step 1: Can you get Kinect data feeding into your code? Don't worry about doing anything with the data, just display it on the screen for now. Googling something like "Processing Kinect" returns a ton of results, or you could check out the Processing libraries page.
Step 2: After you get that working, then can you identify your target point? Then can you track that point? Again, google is your friend. You might also consider treating this as a separate problem and using something like OpenCV to do image processing on the Kinect feed.
Open Kinect by Daniel Shiffman is a pretty good starting point, and it contains a bunch of examples that get you closer to your goal.
That should be a reasonable starting point: break your problem down into smaller steps, then use google searches to approach those steps one at a time. If you get stuck on a specific step, come back and ask a specific question (don't forget the MCVE) and we'll go from there. Good luck.
Related
This is my first question on Stackoverflow, so at first - hi everyone :)
I'm a newbie in image processing, but I have to write an app (in Java) to detect changes between images from a camera (or rather to detect new objects on images).
A camera is taking a picture every minute, all day, so as an input I have a sequence of color images in JPG.
The important things are:
the camera isn't moving, so a background doesn't change. I'm interested only in
detecting objects (e.g. people, animals, cars, ..) between lens and a background
it should be impervious to image noise from a camera or weather (e.g. rain, snow, sun moving - shades)
the only thing I need as an output is an information that sth has changed between two images
I'm interested in as simple solution as possible, but it has to be a working solution.
It doesn't need to be infallible, but it should work correctly in most normal cases.
Of course, I don't expect someone give me a ready to use snippet of a code
(although that would be great! ;) ), but if someone, who knows the topic, gives me some guidelines (steps to do, algorithms or articles to read), I'll be really gratefull. I haven't found nothing appropriate on google and unfortunately I don't have a year to read few books and do a PhD to find a solution :)
you can parse md5 of the image and compare parts of it, and check if they are similar or not, you can refer to this
You can use Keypoint Matching which is almost the same method as 1 you can read about this.
Read about Histogram method
As a simple solution, just subtract one image from the other and look at the differences. Ignore small changes and try to build area of movement and just accept bigger areas.
First question here so sorry if anything I ask is completely stupid.
I'm working in a shape recognition project where it is supposed for me to develop an application that receives two images: an original one and a sketch made by a user. I am supposed to detect contours of the two images and find the best match in the original image corresponding to the sketch made by the user.
I am already learning some basics about the Canny edge detection and was able to get the contours of several images. After having the contours, I need to analyze all contours in the image and find the best match, disregarding translation, rotation, scaling and occlusion.
Then, I found this code that does exactly what I want:
http://www.morethantechnical.com/2012/12/27/2d-curve-matching-in-opencv-w-code/ but is in C++.
Do you know any alternative for similar code in Java or any algorithm that could be useful to me? I also discovered BoofCV but it seems that such task is not implemented.
Thank you for your patience.
EDIT:
I've been searching for other ways of doing this, and I found the Hausdorff distance:
http://cgm.cs.mcgill.ca/~godfried/teaching/cg-projects/98/normand/main.html
Is it possible to modify this algorithm to be rotation invariant? They only talk about translation and scaling.
As you mentioned you already have the source code in C++ and can't find a Java version - possibly your best bet might be to convert the C++ code into Java code. If you don't need all parts of the C++ program, you might want to covert only the parts (classes) that you need.
Conversion from C++ to Java might not be always trivial but I am guessing it might be easier if you know exactly what you want and how you want your program to behave. Below is a link to some conversion tools - although they might not be free.
http://www.researchgate.net/post/How_to_convert_the_C_C_code_to_java2
I thought of writing a piece of software which does Alpha Compositing. I didn't wanted ready made code off from internet so I tried to find research papers and other sources to understand the mathematical algorithms, and initiated to implement.
But, I got lost very quickly. So my question is,
How should I approach these papers to extract the necessary details from it in order to write algorithm based on it. Any specific set of steps which works well?
Desired answer :
Read ...
Extract ...
Understand ...
Implement ...
Note: This question is not limited to only Alpha Compositing, so more generalised approach will be helpful. I have tagged Java and C++, because thats my desired language to implement the image processing.
What I have done so far?
This is not a homework question but it is of course better to say what I know. I have read wiki of Alpha compositing, and few closely related Image compositing research papers. But, I stuck at the next step to take in order to go from understanding to implementation.
Wikipedia
Technical Memo, Image compositing
I'd recommend reading articles with complex formulas with a pencil and paper. Work through the math involved until you have a good grasp on it. Then, you'll be ready to code.
Start with identifying the steps needed to perform your algorithm on some image data. Include all of the steps from loading the image itself into memory all the way through the complex calculations that you may need to perform. Then structure that list into pseudocode. Once you have that, it should be rather easy to code up.
Write pseudocode. Ideally, the authors of the research papers would have done this, but often they don't. Write pseudocode for some simple language like Matlab or possibly Python, and hack away at writing a working implementation based on the psuedocode.
If you understand some parts of the algorithm but not others, then implement your pseudocode into real code for the parts you understand, and leaving comments for the places you don't.
The section from The Pragmatic Programmer on "Tracer Bullets" basically describes this idea. You want to quickly hack together something that takes your data into some form of an output, and then iterate on the body of the code to get it to slowly resemble the algorithm you're trying to produce.
My answer is necessarily somewhat vague. There's no magic bullet for something like this.
Have you implemented any image processing algorithms? Maybe start with something a little simpler, like desaturation/color intensification, reversal (side to side and upside down), rotating, scaling, and compositing images through a mask.
Once you have those figured out, you will be in a very good position to do an alpha composite.
I agree that academic papers seem to go out of their way to make implementation details muddy and uncertain. I find that large amounts of simplification to what is written is needed to begin to perform a practical implementation. In their haste to be general, writers excessively parameterize every aspect. To build useful, reliable software, it is necessary to start with something simple which actually works so that it can be a framework to add features. To do that, it is necessary to throw away 80–90 percent of the academic generality. Often much can be done with a raft of symbolic constants, but abandoning generality (say for four and five dimensional images) doesn't really lose anything in practice.
My suggestion is to first write the algorithm using Matlab to make sure that you understood all the steps and then try to implement using C++ or java.
To add to the good suggestions above, try to write your pseudocode in simple module (Object oriented style ) so has to have a deep understanding of each part of your code while not loosing the big picture. Writing everything in a procedural way is good a the beginning but as the code grow, it might get become hard to keep up will all you are trying to do.
This example cites one of the seminal works on the topic: Compositing Digital Images by Porter & Duff. The class java.awt.AlphaComposite implements the same rules.
First of all, sorry for the vague title. I have no other ideas of what could possibly be put there, but you'll see this for yourself as you read on.
I am a very new Java developer for android and a martian to game development, therefore my question is not so related to particulars as it is related to theory and possibilities.
I'm interested in how I can develop my game so if holding the phone horizontally and it is tilted one way or another, an object will move in that direction. I'm sure this is very common and easily done but what about if I wanted the top speed to increase the further it was turned, and the acceleration to increase the quicker it was turned?
I honestly have no idea of the complexity of this question, whether you will laugh and give me one line of code or whether it's something you just can't teach.
Either way, thanks for reading, I look forward to your responses.
Check this out http://mobilestrategist.blogspot.com/2010/01/android-accelerometer-and-orientation.html
This gives you what you need to do what you're asking for, but as the other answer suggests, you may be running before you crawl here. I have been writing Android for 2 years and have yet to take advantage of the accelerometer. Though if you're just looking to noodle around with the device's capabilities, this is as good a place to start as any, I suppose.
You could read about sensors & sensor events.
TYPE_ACCELEROMETER is perhaps what you are looking for...
I have as an input a 2D polygon with holes, and I need to find it's straight skeleton, like in the picture:
(source: cgal.org)
Maybe there is a good Java library for it?
And if not, can you point me to the good explanation of the algorithm, so I could implement it myself? (I haven't found good resources on Google)
I wrote this a little while back. Not sure if it's robust enough.
https://github.com/twak/campskeleton
(edited for 2018...)
See http://www.sable.mcgill.ca/~dbelan2/roofs/roofs.html which contains an applet.
You may be able to use the JTS Topology Suite. It is a very capable library that I've used on a number of projects - never for straight skeleton, but it may be possible.
Edit:
Ah. I see that "Straight Skeleton" is a technical term. The wikipedia article references several algorithms. Have you looked at those?
As I understand it, you have a (convex?) polygon. From it, you subtract 1 or more (potentially non-convex) polygons. You want to turn the result into a set of polygons without holes. Are there extra rules that you're trying to apply?
I have a hard time coming up with a set of rules from the example that you provided. The outer polygons are non-convex; so it doesn't seem like you're trying to find a convex set to represent the result (which is a relatively common task).
If you could use the breakdown shown below, the algorithm is pretty simple. Can you clarify?
Can I ask u what is your purpose for finding Straight skeleton? Is it personal or commercial? I would be interested in knowing how you r using it to solve real time problems? I do have a java library that does that. My algorithm is listed here http://web.stcloudstate.edu/rsarnath/skeleton/definition.htm