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  • obtain OpenGL camera(view) matrix from openCV findhomography

    - by user1828449
    I want to build an AR application on Android by opencv and opengl. I found GL_MODELVIEW can place camera and model in world coordinates like the following link I tried to load a simple model-view matrix by gl.glLoadMatrixf(newMat, 0); and it works so I want to draw 3d model on the top of my target image if i got the four corner points of the target image because model-view matrix is needed I want to know if I can obtain the camera view matrix by opencv's findhomography

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  • maple 13 tridiagonal matrix help

    - by user292569
    i am trying to make a 100 x 100 tridiagonal matrix with 2's going down the diagonal and -1's surrounding the 2's. i can make a tridiagonal matrix with only 1's in the three diagonals and preform matrix addition to get what i want, but i want to know if there is a way to customize the three diagonals to what ever you want. maplehelp doesn't list anything useful.

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  • How to represent double values as circles in a 2d matrix in java

    - by marco
    Hello, so I want to write a matrix explorer which enables me to reorder rows and columns of a matrix. For this porpouse I used the Jtable class. Now the problem that I have is that it is very difficult to reorder a matrix by looking at double values, so I would like to print the matrix not with the double values but with circles in which the radius of the circle represents the value. So that I can tell the difference between big values and small values quicker. Anybody has any idea how I can turn this double values into filled circles with JTable or any table class for that matter?

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  • High speed matrix manipulation in c#?

    - by Donnie
    I'm working on some image manipulation code in c# and need to do some matrix operations (specifically 2D convolution). I have the code written in matlab which uses the conv2 function ... is there a library for C# / .NET that does good high-speed matrix manipulations? I'd be fine if it requires some specific GPU and does the matrix math on-GPU if that's what it takes.

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  • Numpy Matrix keeps giving me an Error,

    - by uberjumper
    Okay this is werid, i keep getting the error, randomly. ValueError: matrix must be 2-dimensional So i tracked it down, and cornered it to basically something like this: a_list = [[(1,100) for _ in range(32)] for _ in range(32)] numpy.matrix(a_list) Whats wrong with this? If i print a_list it is clearly a 2d matrix of tuples, however numpy does not believe so.

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  • How can I save and read to XML the new C++ style matrix objects in OpenCV?

    - by neuviemeporte
    The old, C style cvMat matrices could be passed to the cvSave() function for easy writing to an XML file. The new C++ style cv::Mat and cv::Mat_ matrices are not accepted by this function. The OpenCV reference has a section on XML persistence, but the three classes (FileStorage, FileNode and FileNodeIterator) lack any description or example and I can't figure out how to use them from the interface. Thanks.

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  • C++ Matrix class hierachy

    - by bpw1621
    Should a matrix software library have a root class (e.g., MatrixBase) from which more specialized (or more constrained) matrix classes (e.g., SparseMatrix, UpperTriangluarMatrix, etc.) derive? If so, should the derived classes be derived publicly/protectively/privately? If not, should they be composed with a implementation class encapsulating common functionality and be otherwise unrelated? Something else? I was having a conversation about this with a software developer colleague (I am not per se) who mentioned that it is a common programming design mistake to derive a more restricted class from a more general one (e.g., he used the example of how it was not a good idea to derive a Circle class from an Ellipse class as similar to the matrix design issue) even when it is true that a SparseMatrix "IS A" MatrixBase. The interface presented by both the base and derived classes should be the same for basic operations; for specialized operations, a derived class would have additional functionality that might not be possible to implement for an arbitrary MatrixBase object. For example, we can compute the cholesky decomposition only for a PositiveDefiniteMatrix class object; however, multiplication by a scalar should work the same way for both the base and derived classes. Also, even if the underlying data storage implementation differs the operator()(int,int) should work as expected for any type of matrix class. I have started looking at a few open-source matrix libraries and it appears like this is kind of a mixed bag (or maybe I'm looking at a mixed bag of libraries). I am planning on helping out with a refactoring of a math library where this has been a point of contention and I'd like to have opinions (that is unless there really is an objective right answer to this question) as to what design philosophy would be best and what are the pros and cons to any reasonable approach.

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  • Implementation of a distance matrix of a binary tree that is given in the adjacency-list representation

    - by Denise Giubilei
    Given this problem I need an O(n²) implementation of this algorithm: "Let v be an arbitrary leaf in a binary tree T, and w be the only vertex connected to v. If we remove v, we are left with a smaller tree T'. The distance between v and any vertex u in T' is 1 plus the distance between w and u." This is a problem and solution of a Manber's exercise (Exercise 5.12 from U. Manber, Algorithms: A Creative Approach, Addison-Wesley (1989).). The thing is that I can't deal properly with the adjacency-list representation so that the implementation of this algorithm results in a real O(n²) complexity. Any ideas of how the implementation should be? Thanks.

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  • building a pairwise matrix in scipy/numpy in Python from dictionaries

    - by user248237
    I have a dictionary whose keys are strings and values are numpy arrays, e.g.: data = {'a': array([1,2,3]), 'b': array([4,5,6]), 'c': array([7,8,9])} I want to compute a statistic between all pairs of values in 'data' and build an n by x matrix that stores the result. Assume that I know the order of the keys, i.e. I have a list of "labels": labels = ['a', 'b', 'c'] What's the most efficient way to compute this matrix? I can compute the statistic for all pairs like this: result = [] for elt1, elt2 in itertools.product(labels, labels): result.append(compute_statistic(data[elt1], data[elt2])) But I want result to be a n by n matrix, corresponding to "labels" by "labels". How can I record the results as this matrix? thanks.

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  • i want to find determinant of 4x4 matrix in c#

    - by vj4u
    i want to find determinant of 4x4 matrix in c# please help urgent int ss = 4; int count = 0; int[,] matrix=new int[ss,ss]; ArrayList al = new ArrayList() {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16 }; for (int i = 0; i < ss; i++) { for (int j = 0; j < ss; j++) { matrix[i, j] =Convert.ToInt32( al[count]); ++count; Response.Write(matrix[i, j] + " "); } Response.Write("<br/>"); }

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  • R - indirectly calling a matrix using a string

    - by Boris Senderovich
    Example: There is a matrix of data called VE There is a vector of string where the first element is the string VE. I need to indirectly call the string and be able to access data. For example if I need the 6th column of matrix VE then I want to do: Vector[1][,6] Essentially I need R to start reading those string as if they are the matrix names that are already in this page. I need this syntax to be dynamic because I am putting it in a loop.

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  • Is the use of union in this matrix class completely safe?

    - by identitycrisisuk
    Unions aren't something I've used that often and after looking at a few other questions on them here it seems like there is almost always some kind of caveat where they might not work. Eg. structs possibly having unexpected padding or endian differences. Came across this in a math library I'm using though and I wondered if it is a totally safe usage. I assume that multidimensional arrays don't have any extra padding and since the type is the same for both definitions they are guaranteed to take up exactly the same amount of memory? template<typename T> class Matrix44T { ... union { T M[16]; T m[4][4]; } m; }; Are there any downsides to this setup? Would the order of definition make any difference to how this works?

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  • Find largest rectangle containing only zeros in an N&times;N binary matrix

    - by Rajendra
    Given an NxN binary matrix (containing only 0's or 1's), how can we go about finding largest rectangle containing all 0's? Example: I 0 0 0 0 1 0 0 0 1 0 0 1 II->0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 <--IV 0 0 1 0 0 0 IV is a 6×6 binary matrix; the return value in this case will be Cell 1: (2, 1) and Cell 2: (4, 4). The resulting sub-matrix can be square or rectangular. The return value can also be the size of the largest sub-matrix of all 0's, in this example 3 × 4.

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  • Problem with DirectX scene-graph

    - by Alex
    I'm trying to implement a basic scene graph in DirectX using C++. I am using a left child-right sibling binary tree to do this. I'm having trouble updating each node's world transformation relative to its parent (and its parent's parent etc.). I'm struggling to get it to work recursively, though I can get it to work like this: for(int i = 0; i < NUM_OBJECTS; i++) { // Initialize to identity matrix. D3DXMatrixIdentity(&mObject[i].toWorldXForm); int k = i; while( k != -1 ) { mObject[i].toWorldXForm *= mObject[k].toParentXForm; k = mObject[k].parent; } } toWorldXForm is the object's world transform and toParentXForm is the object's transform relative to the parent. I want to do this using a method within my object class (the code above is in my main class). This is what I've tried but it doesn't work (only works with nodes 1 generation away from the root) if (this->sibling != NULL) this->sibling->update(toParentXForm); D3DXMatrixIdentity(&toWorldXForm); this->toWorldXForm *= this->toParentXForm; this->toWorldXForm *= toParentXForm; toParentXForm *= this->toParentXForm; if (this->child != NULL) this->child->update(toParentXForm); Sorry if I've not been clear, please tell me if there's anything else you need to know. I've no doubt it's merely a silly mistake on my part, hopefully an outside view will be able to spot the problem.

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  • Precision loss when transforming from cartesian to isometric

    - by Justin Skiles
    My goal is to display a tile map in isometric projection. This tile map has 25 tiles across and 25 tiles down. Each tile is 32x32. See below for how I'm accomplishing this. World Space World Space to Screen Space Rotation (45 degrees) Using a 2D rotation matrix, I use the following: double rotation = Math.PI / 4; double rotatedX = ((tileWorldX * Math.Cos(rotation)) - ((tileWorldY * Math.Sin(rotation))); double rotatedY = ((tileWorldX * Math.Sin(rotation)) + (tileWorldY * Math.Cos(rotation))); World Space to Screen Space Scale (Y-axis reduced by 50%) Here I simply scale down the Y value by a factor of 0.5. Problem And it works, kind of. There are some tiny 1px-2px gaps between some of the tiles when rendering. I think there's some precision loss somewhere, or I'm not understanding how to get these tiles to fit together perfectly. I'm not truncating or converting my values to non-decimal types until I absolutely have to (when I pass to the render method, which only takes integers). I'm not sure how to guarantee pixel perfect rendering precision when I'm rotating and scaling on a level of higher precision. Any advice? Do I need to supply for information?

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  • How to do geometric projection shadows?

    - by John Murdoch
    I have decided that since my game world is mostly flat I don't need better shadows than geometric projections - at least for now. The only problem is I don't even know how to do those properly - that is to produce a 4x4 matrix which would render shadows for my objects (that is, I guess, project them on a horizontal XZ plane). I would like a light source at infinity (e.g., the sun at some point in the sky) and thus parallel projection. My current code does something that looks almost right for small flying objects, but actually is a very rude approximation, as it doesn't project the objects onto the ground, but simply moves them there (I think). Also it always wrongly assumes the sun is always on the zenith (projecting straight down). Gdx.gl20.glEnable(GL10.GL_BLEND); Gdx.gl20.glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA); //shells shellTexture.bind(); shader.begin(); for (ShellState state : shellStates.values()) { transform.set(camera.combined); transform.mul(state.transform); shader.setUniformMatrix("u_worldView", transform); shader.setUniformi("u_texture", 0); shellMesh.render(shader, GL10.GL_TRIANGLES); } shader.end(); // shadows shader.begin(); for (ShellState state : shellStates.values()) { transform.set(camera.combined); m4.set(state.transform); state.transform.getTranslation(v3); m4.translate(0, -v3.y + 0.5f, 0); // TODO HACK: + 0.5f is a hack to ensure the shadow appears above the ground; this is overall a hack as we are just moving the shell to the surface instead of projecting it on the surface! transform.mul(m4); shader.setUniformMatrix("u_worldView", transform); shader.setUniformi("u_texture", 0); // TODO: make shadow black somehow shellMesh.render(shader, GL10.GL_TRIANGLES); } shader.end(); Gdx.gl.glDisable(GL10.GL_BLEND); So my questions are: a) What is the proper way to produce a Matrix4 to pass to openGL which would render the shadows for my objects? b) I am supposed to use another fragment shader for the shadows which would paint them in semi-transparent grey, correct? c) The limitation of this simplistic approach is that whenever there is some object on the ground (it is not flat) the shadows will not be drawn, correct? d) Do I need to add something very small to the y (up) coordinate to avoid z-fighting with ground textures? Or is the fact they will be semi-transparent enough to resolve that problem?

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  • Glm Vector Transformations [duplicate]

    - by Reanimation
    This question already has an answer here: Car-like Physics - Basic Maths to Simulate Steering 2 answers I have a cube rendered on the screen which represents a car (or similar). Using Projection/Model matrices and Glm I am able to move it back and fourth along the axes and rotate it left or right. I'm having trouble with the vector mathematics to make the cube move forwards no matter which direction it's current orientation is. (ie. if I would like, if it's rotated right 30degrees, when it's move forwards, it travels along the 30degree angle on a new axes). I hope I've explained that correctly. This is what I've managed to do so far in terms of using glm to move the cube: glm::vec3 vel; //velocity vector void renderMovingCube(){ glUseProgram(movingCubeShader.handle()); GLuint matrixLoc4MovingCube = glGetUniformLocation(movingCubeShader.handle(), "ProjectionMatrix"); glUniformMatrix4fv(matrixLoc4MovingCube, 1, GL_FALSE, &ProjectionMatrix[0][0]); glm::mat4 viewMatrixMovingCube; viewMatrixMovingCube = glm::lookAt(camOrigin, camLookingAt, camNormalXYZ); vel.x = cos(rotX); vel.y=sin(rotX); vel*=moveCube; //move cube ModelViewMatrix = glm::translate(viewMatrixMovingCube,globalPos*vel); //bring ground and cube to bottom of screen ModelViewMatrix = glm::translate(ModelViewMatrix, glm::vec3(0,-48,0)); ModelViewMatrix = glm::rotate(ModelViewMatrix, rotX, glm::vec3(0,1,0)); //manually turn glUniformMatrix4fv(glGetUniformLocation(movingCubeShader.handle(), "ModelViewMatrix"), 1, GL_FALSE, &ModelViewMatrix[0][0]); //pass matrix to shader movingCube.render(); //draw glUseProgram(0); } keyboard input: void keyboard() { char BACKWARD = keys['S']; char FORWARD = keys['W']; char ROT_LEFT = keys['A']; char ROT_RIGHT = keys['D']; if (FORWARD) //W - move forwards { globalPos += vel; //globalPos.z -= moveCube; BACKWARD = false; } if (BACKWARD)//S - move backwards { globalPos.z += moveCube; FORWARD = false; } if (ROT_LEFT)//A - turn left { rotX +=0.01f; ROT_LEFT = false; } if (ROT_RIGHT)//D - turn right { rotX -=0.01f; ROT_RIGHT = false; } Where am I going wrong with my vectors? I would like change the direction of the cube (which it does) but then move forwards in that direction.

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  • Dot Matrix printing in C# ?

    - by Dale
    I'm trying to print to Dot Matrix printers (various models) out of C#, currently I'm using Win32 API (you can find alot of examples online) calls to send escape codes directly to the printer out of my C# application. This works great, but... My problem is because I'm generating the escape codes and not relying on the windows print system the printouts can't be sent to any "normal" printers or to things like PDF print drivers. (This is now causing a problem as we're trying to use the application on a 2008 Terminal Server using Easy Print [Which is XPS based]) The question is: How can I print formatted documents (invoices on pre-printed stationary) to Dot Matrix printers (Epson, Oki and Panasonic... various models) out of C# not using direct printing, escape codes etc. **Just to clarify, I'm trying things like GDI+ (System.Drawing.Printing) but the problem is that its very hard, to get things to line up like the old code did. (The old code sent the characters direct to the printer bypassing the windows driver.) Any suggestions how things could be improved so that they could use GDI+ but still line up like the old code did?

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  • Changing the color of dot depending from value on Morris js graph

    - by Michal Lipa
    Im rendering graph by morris js. Im using data from mysql database by JSON. Everything works fine, but I would like to add one more feature to the graph. (change dot color if there is something in buy action). My JSON: [{"longdate":"2014-08-20 18:20:01","price":"1620","action":"buy"},{"longdate":"2014-08-20 18:40:01","price":"1640","action":""},{"longdate":"2014-08-20 19:00:01","price":"1620","action":""}] So I would like to change dot color for values with buy action. My code for graph: $.getJSON('results.json', function(day_data) { Morris.Line({ element: 'graph', data: day_data, xkey: 'longdate', ykeys: ['price'], labels: ['Cena'], lineColors: lineColor, pointSize: 0, hoverCallback: function(index, options, content) { var date = "<b><font color='black'>Data: "+day_data[index]['longdate']+"</font></b><br>"; var param1 = "<font color='"+lineColor[0]+"'>Cena - "+day_data[index]['price']+"</font><br>"; return date+param1; }, xLabelFormat : function (x) { return changeDateFormat(x); } /*My TRIAL if(action == 'buy'){ pointSize: 4, lineColors: green, } */ }); }); So my code doesnt work, how can I make this working?

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  • Office 2011 Mac - Unable to save Word files, plus normal.dot alert errors

    - by Jeff D
    There are actually 3 errors here. When I open Word, I get: Word cannot open the existing global template. () If I create a file, type a character and try to save to the desktop (that I have no problems writing to otherwise), I get: Word cannot save or create this file. The disk may be full or write-protected. Try one or more of the following: * Free more memory * Make sure that the disk you want to save the file on is not full, write-protected, or damaged. () I am just saving to the desktop, and I can save excel files (or anything else) there. After the failure, if I save again, the default file name becomes: .doc...doc Weird. Finally, when I close word completely, I get: Do you want to replace the existing Normal.dotm.

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  • Apache Alias subfolder and starting with dot

    - by MauricioOtta
    I have a multi purpose server running ArchLinux that currently serves multiple virtual hosts from /var/www/domains/EXAMPLE.COM/html /var/www/domains/EXAMPLE2.COM/html I deploy those websites (mostly using Kohana framework) using a Jenkins job by checking out the project, removes the .git folder and ssh-copy the tar.gz to /var/www/domains/ on the server and untars it. Since I don't want to have to re-install phpMyAdmin after each deploy, I decided to use an alias. I would like the alias to be something like /.tools/phpMyAdmin/ so I could have more "tools" later if I wanted to. I have tried just changing the default httpd-phpmyadmin.conf that was installed by following the official WIKI: https://wiki.archlinux.org/index.php/Phpmyadmin Alias /.tools/phpMyAdmin/ "/usr/share/webapps/phpMyAdmin" <Directory "/usr/share/webapps/phpMyAdmin"> AllowOverride All Options FollowSymlinks Order allow,deny Allow from all php_admin_value open_basedir "/var/www/:/tmp/:/usr/share/webapps/:/etc/webapps:/usr/share/pear/" </Directory> Changing only that, doesn't seem to work with my current setup on the server, and apache forwards the request to the framework which 404s (as there's no route to handle /.tools/phpAdmin). I have Mass Virtual hosting enable and setup like this: # # Use name-based virtual hosting. # NameVirtualHost *:8000 # get the server name from the Host: header UseCanonicalName On # splittable logs LogFormat "%{Host}i %h %l %u %t \"%r\" %s %b" vcommon CustomLog logs/access_log vcommon <Directory /var/www/domains> # ExecCGI is needed here because we can't force # CGI execution in the way that ScriptAlias does Options FollowSymLinks ExecCGI AllowOverride All Order allow,deny Allow from all </Directory> RewriteEngine On # a ServerName derived from a Host: header may be any case at all RewriteMap lowercase int:tolower ## deal with normal documents first: # allow Alias /icons/ to work - repeat for other aliases RewriteCond %{REQUEST_URI} !^/icons/ # allow CGIs to work RewriteCond %{REQUEST_URI} !^/cgi-bin/ # do the magic RewriteCond %{SERVER_NAME} ^(www\.|)(.*) RewriteRule ^/(.*)$ /var/www/domains/${lowercase:%2}/html/$1 ## and now deal with CGIs - we have to force a MIME type RewriteCond %{REQUEST_URI} ^/cgi-bin/ RewriteRule ^/(.*)$ /var/www/domains/${lowercase:%{SERVER_NAME}}/cgi-bin/$1 [T=application/x-httpd-cgi] There is also nginx running on this server on port 80 as a reverse proxy for Apache: location ~ \.php$ { proxy_pass http://127.0.0.1:8000; } Everything else was setup by following the official WIKI so I don't think those would cause trouble. Do I need to have the alias for phpMyAdmin setup along the mass virtual hosting or can it be in a separate include file for that alias to work?

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