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  • Matlab matrix translation and rotation multiple times

    - by pinnacler
    I have a map of individual trees from a forest stored as x,y points in a matrix. I call it fixedPositions. It's cartesian and (0,0) is the origin. I would like 0/360 degrees to be the top of the screen and 90 degrees to be to the right. Given a velocity and a heading, i.e. .5 m/s and 60 degrees (2 o'clock equivalent on a watch), how do I rotate that x,y points, so that the new origin is centered at (.5cos(60),.5sin(60)) and 60 degrees is now at the top of the screen? Then if I were to give you another heading and speed, i.e. 0 degrees and 2m/s, it should calculate it from the last point, not the original fixedPositions origin. I've wasted my day trying to figure this out. I wish I took matrix algebra but I'm at a loss. I tried doing cos(30) and even those wouldn't compute correctly, which after an hour I realize were in radians.

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  • Understanding The Convolution Matrix

    - by Ryan Naddy
    I am learning about the Convolution Matrix, and I understand how they work, but I don't understand how to know before hand what the output of a Matrix will look like. For example lets say I want to add a blur to an image, I could guess 10,000+ different combinations of numbers before I get the correct one. I do know though that this formula will give me a blur effect, but I have no idea why. float[] sharpen = new float[] { 1/9f, 1/9f, 1/9f, 1/9f, 1/9f, 1/9f, 1/9f, 1/9f, 1/9f }; Can anyone either explain to me how this works or point me to some article, that explains this? I would like to know before hand what a possible output of the matrix will be without guessing. Basically I would like to know why do we put that number in the filed, and why not some other number?

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  • uneven illuminated images

    - by coul
    How to get rid of uneven illumination from images, that contain text data, usually printed but may be handwritten? It can have some spots of lights because the light reflected while making picture. I've seen the Halcon program's segment_characters function that is doing this work perfectly, but it is not open source. I wish to convert an image to the image that has a constant illumination at background and more dark colored regions of text. So that binarization will be easy and without noise. The text is assumed to be dark colored than it's background. Any ideas?

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  • CUDA small kernel 2d convolution - how to do it

    - by paulAl
    I've been experimenting with CUDA kernels for days to perform a fast 2D convolution between a 500x500 image (but I could also vary the dimensions) and a very small 2D kernel (a laplacian 2d kernel, so it's a 3x3 kernel.. too small to take a huge advantage with all the cuda threads). I created a CPU classic implementation (two for loops, as easy as you would think) and then I started creating CUDA kernels. After a few disappointing attempts to perform a faster convolution I ended up with this code: http://www.evl.uic.edu/sjames/cs525/final.html (see the Shared Memory section), it basically lets a 16x16 threads block load all the convolution data he needs in the shared memory and then performs the convolution. Nothing, the CPU is still a lot faster. I didn't try the FFT approach because the CUDA SDK states that it is efficient with large kernel sizes. Whether or not you read everything I wrote, my question is: how can I perform a fast 2D convolution between a relatively large image and a very small kernel (3x3) with CUDA?

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  • Embarrassingly parallel workflow creates too many output files

    - by Hooked
    On a Linux cluster I run many (N > 10^6) independent computations. Each computation takes only a few minutes and the output is a handful of lines. When N was small I was able to store each result in a separate file to be parsed later. With large N however, I find that I am wasting storage space (for the file creation) and simple commands like ls require extra care due to internal limits of bash: -bash: /bin/ls: Argument list too long. Each computation is required to run through a qsub scheduling algorithm so I am unable to create a master program which simply aggregates the output data to a single file. The simple solution of appending to a single fails when two programs finish at the same time and interleave their output. I have no admin access to the cluster, so installing a system-wide database is not an option. How can I collate the output data from embarrassingly parallel computation before it gets unmanageable?

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  • I/O Asynchronous Completion

    - by lockedscope
    In the following, it is said that an I/O handle must be associated with the thread pool but i could not find where in the given example an handle is associated with the thread. Which function or code helps to bind the file handle in that example? Using asynchronous I/O completion events, a thread from the thread pool processes data only when the data is received, and once the data has been processed, the thread returns to the thread pool. To make an asynchronous I/O call, an operating-system I/O handle must be associated with the thread pool and a callback method must be specified. When the I/O operation completes, a thread from the thread pool invokes the callback method. http://msdn.microsoft.com/en-us/library/aa720215(VS.71).aspx

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  • How do I measure distances in an image?

    - by Ram Bhat
    Let's say we have an image like so Let's say we've already used filters and an edge detection algorithm in this pic. Now my goal is to measure distances (NOT actual distances, distance can be in any arbitrary unit) . eg: How do I find the length of the hall? (until the window) Or the height of the bookshelves? How exactly do you place the "scale" and measure. I'm looking for ideas. However it would help if the answers were in terms of OpenCV.

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  • function taking in an input image and different kernel size

    - by drifterOcean19
    I have this filtering function that takes an input image, performs convolution using a given kernel, and returns the resulting image. However, I can't seem to work it out how to make it takes different kernel sizes.For example instead of pre-defined 3x3 kernel as below in the code, it could instead take 5x5 or 7x7. and then the user could input the type of kernel/filter they want(Depending on the intended effect). I can't seem to put my head around it. i'm quite new to matlab. function [newImg] = kernelFunc(imgB) img=imread(imgB); figure,imshow(img); img2=zeros(size(img)+2); newImg=zeros(size(img)); for rgb=1:3 for x=1:size(img,1) for y=1:size(img,2) img2(x+1,y+1,rgb)=img(x,y,rgb); end end end for rgb=1:3 for i= 1:size(img2,1)-2 for j=1:size(img2,2)-2 window=zeros(9,1); inc=1; for x=1:3 for y=1:3 window(inc)=img2(i+x-1,j+y-1,rgb); inc=inc+1; end end kernel=[1;2;1;2;4;2;1;2;1]/16; med=window.*kernel; disp(med); med=sum(med); med=floor(med); newImg(i,j,rgb)=med; end end end newImg=uint8(newImg); figure,imshow(newImg); end

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  • Expert system for writing programs?

    - by aaa
    I am brainstorming an idea of developing a high level software to manipulate matrix algebra equations, tensor manipulations to be exact, to produce optimized C++ code using several criteria such as sizes of dimensions, available memory on the system, etc. Something which is similar in spirit to tensor contraction engine, TCE, but specifically oriented towards producing optimized rather than general code. The end result desired is software which is expert in producing parallel program in my domain. Does this sort of development fall on the category of expert systems? What other projects out there work in the same area of producing code given the constraints?

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  • How to make disconnected closed curves connected by adding a shortest path using MATLAB?

    - by user198729
    bwlabel can be used to get disconnected objects in an image: [L Ne] = bwlabel(image); I want to make the objects(But my target is only the contours(closed curve) of these objects) connected by adding a shortest path where necessary. How do I approach this? UPDATE Or how to dilate the closed curves so that they get connected? How to calculate the shortest path between two disconnected closed curves?

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  • ASP.NET MVC2 - specific fields in form pass via a specific object?

    - by ile
    In database I have Contacts table: ContactID (int) FirstName (varchar) LastName (varchar) ... XmlFields (xml) // This field is xml type To create a new contact, I created two classes - one for regular fields and other to display fields from XmlFields field. In Controller, I have following: public ActionResult Create(Contact contact, FormCollection collection) ... Regular field I catch with contact object and those that need to be stored as xml in XmlFields I try to catch with collection object. Problem is that collection object catches all fields, so I wonder if it is possible to isolate xml fields when posting to a specific object so that I can easily manipulate with them. I need this in separated objects because these xml fields are going to be generated dynamically and will be different for every user. Thanks in advance, Ile

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  • Saving a remote image with cURL?

    - by thebluefox
    Morning all, Theres a few questions around this but none that really answer my question, as far as I ca understand. Basically I have a GD script that deals with resizing and caching images on our server, but I need to do the same with images stored on a remote server. So, I'm wanting to save the image locally, then resize and display it as normal. I've got this far... $file_name_array = explode('/', $filename); $file_name_array_r = array_reverse($file_name_array); $save_to = 'system/cache/remote/'.$file_name_array_r[1].'-'.$file_name_array_r[0]; $ch = curl_init($filename); $fp = fopen($save_to, "wb"); // set URL and other appropriate options $options = array(CURLOPT_FILE => $fp, CURLOPT_HEADER => 0, CURLOPT_FOLLOWLOCATION => 1, CURLOPT_TIMEOUT => 60); // 1 minute timeout (should be enough) curl_setopt_array($ch, $options); curl_exec($ch); curl_close($ch); fclose($fp); This creates the image file, but does not copy it accross? Am I missing the point? Cheers guys.

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  • Replacing all GUIDs in a file with new GUIDs from the command line

    - by Josh Petrie
    I have a file containing a large number of occurrences of the string Guid="GUID HERE" (where GUID HERE is a unique GUID at each occurrence) and I want to replace every existing GUID with a new unique GUID. This is on a Windows development machine, so I can generate unique GUIDs with uuidgen.exe (which produces a GUID on stdout every time it is run). I have sed and such available (but no awk oddly enough). I am basically trying to figure out if it is possible (and if so, how) to use the output of a command-line program as the replacement text in a sed substitution expression so that I can make this replacement with a minimum of effort on my part. I don't need to use sed -- if there's another way to do it, such as some crazy vim-fu or some other program, that would work as well -- but I'd prefer solutions that utilize a minimal set of *nix programs since I'm not really on *nix machines. To be clear, if I have a file like this: etc etc Guid="A" etc etc Guid="B" I would like it to become this: etc etc Guid="C" etc etc Guid="D" where A, B, C, D are actual GUIDs, of course. (for example, I have seen xargs used for things similar to this, but it's not available on the machines I need this to run on, either. I could install it if it's really the only way, although I'd rather not)

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  • how many processors can I get in a block on cuda GPU?

    - by Vickey
    hi all, I have two questions to ask 1) If I create only one block of threads in cuda and execute the my parallel program on it then is it possible that more than one processors would be given to single block so that my program get some benefit of multiprocessor platform ? 2) can I synchronize the threads of different blocks ? if yes please give some hints. Thanks in advance since I know I'll get replies as always I get.

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  • Why '.png' files produced by ImageMagick are so much bigger than '.jpg' & '.gif' files?

    - by Nick Gorbikoff
    Hello. I'm using ImageMagick to convert some files from one format to another. I was always under the impression that .png files were supposed to be as big/small as .jpg if not smaller, and definitely smaller than .gif. However when I run convert photo.jpg photo.png The files I'm getting out is about 6 times bigger than the original jpg. Original jpg is a regular photo about 300x500 px, 52 kb. Output is a proper png of the same dimensions, but size is about 307 kb? Does anyoone know what the hack is going on? Am I doing something wrong? P.S.: I tried both on Debian and Windows with the same results.

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  • How to read and save data from text file with variable number of columns in a Matrix in Matlab

    - by khan
    I have a text file with integer values. each row contains information about specific object. But unfortunately each row has different number of column. because of which when i try to use file_content = load('txtfile.txt'); it gives me error message that previous number of columns does not match. i also tried to use fgetl, fscanf, etc function but was unsuccessful. Can anybody give me a piece of code, or help me how to read a txt file and save in matrix in matlab. Three sample rows are given below. 1 1 1 1 1 95 17 54 111 92 17 54 111 92 17 54 111 92 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 54 109 92 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 58 109 96 15 58 109 96 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 58 109 96 15 56 109 94 15 56 109 94 15 58 109 96 15 58 109 96 15 56 109 94 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 17 58 111 96 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 56 109 94 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 1 1 1 2 96 185 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 15 56 109 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 54 107 92 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 13 56 107 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 54 109 92 15 54 109 92 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 1 1 1 3 186 245 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 56 109 94 15 58 109 96 15 58 109 96 15 58 109 96 15 58 109 96 13 58 107 96 13 56 107 94 13 56 107 94 13 58 107 96 13 58 107 96 13 58 107 96 13 58 107 96 13 58 107 96 13 56 107 94 13 58 107 96 13 58 107 96 13 58 107 96 13 58 107 96 13 58 107 96 13 58 107 96 13 58 107 96 13 58 107 96 13 58 107 96 13 58 107 96 13 58 107 96 13 60 107 98 13 58 107 96 13 58 107 96 15 58 109 96 13 58 107 96 As you can see the rows doesn't have equal number of columns. So how can i read and save it in a Matrix. Any help in this regards will be highly appreciated. Thanks

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  • .NET: How to ignore comments when reading a XML file into a XmlDocument?

    - by tunnuz
    Hello, I am trying to read a XML document with C#, I am doing it this way: XmlDocument myData = new XmlDocument(); myData.Load("datafile.xml"); anyway, I sometimes get comments when reading XmlNode.ChildNodes. Is there a way to avoid that? I know that you can avoid reading comments if you use XmlReader, but then, how to get the XmlDocument out of a XmlReader? Thank you Tommaso

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  • How to write efficient code for extracting Noun phrases?

    - by Arun Abraham
    I am trying to extract phrases using rules such as the ones mentioned below on text which has been POS tagged 1) NNP - NNP (- indicates followed by) 2) NNP - CC - NNP 3) VP - NP etc.. I have written code in this manner, Can someone tell me how i can do in a better manner. List<String> nounPhrases = new ArrayList<String>(); for (List<HasWord> sentence : documentPreprocessor) { //System.out.println(sentence.toString()); System.out.println(Sentence.listToString(sentence, false)); List<TaggedWord> tSentence = tagger.tagSentence(sentence); String lastTag = null, lastWord = null; for (TaggedWord taggedWord : tSentence) { if (lastTag != null && taggedWord.tag().equalsIgnoreCase("NNP") && lastTag.equalsIgnoreCase("NNP")) { nounPhrases.add(taggedWord.word() + " " + lastWord); //System.out.println(taggedWord.word() + " " + lastWord); } lastTag = taggedWord.tag(); lastWord = taggedWord.word(); } } In the above code, i have done only for NNP followed by NNP extraction, how can i generalise it so that i can add other rules too. I know that there are libraries available for doing this , but wanted to do this manually.

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  • What hash algorithms are paralellizable? Optimizing the hashing of large files utilizing on mult-co

    - by DanO
    I'm interested in optimizing the hashing of some large files (optimizing wall clock time). The I/O has been optimized well enough already and the I/O device (local SSD) is only tapped at about 25% of capacity, while one of the CPU cores is completely maxed-out. I have more cores available, and in the future will likely have even more cores. So far I've only been able to tap into more cores if I happen to need multiple hashes of the same file, say an MD5 AND a SHA256 at the same time. I can use the same I/O stream to feed two or more hash algorithms, and I get the faster algorithms done for free (as far as wall clock time). As I understand most hash algorithms, each new bit changes the entire result, and it is inherently challenging/impossible to do in parallel. Are any of the mainstream hash algorithms parallelizable? Are there any non-mainstream hashes that are parallelizable (and that have at least a sample implementation available)? As future CPUs will trend toward more cores and a leveling off in clock speed, is there any way to improve the performance of file hashing? (other than liquid nitrogen cooled overclocking?) or is it inherently non-parallelizable?

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