camera frame world coordinates relative to fiducial
opencv,computer-vision,camera-calibration,perspectivecamera
What do you mean under world coordinates? If you mean object coordinates then you should use the inverse transformation of solvepnp's result. Given a view matrix [R|t], we have that inv([R|t]) = [R'|-R'*t], where R' is the transpose of R. In OpenCV: cv::Mat rvec, tvec; cv::solvePnP(objectPoints, imagePoints, intrinsics, distortion, rvec,...
Orthographic projection of 3D shape libgdx
3d,libgdx,2d,perspectivecamera,orthographic
An orthographic camera (luckily) does not ignore z. Simply said, it is basically a different projection, namely it has a box frustum instead of a pyramid. Check this article for a more in depth explanation: http://www.badlogicgames.com/wordpress/?p=1550 Note that by default the camera near value = 1f and the far value...
Trying to understand the math behind the perspective matrix in WebGL
math,matrix,opengl-es,webgl,perspectivecamera
Let's see if I can explain this, or maybe after reading this you can come up with a better way to explain it. The first thing to realize is WebGL requires clipspace coordinates. They go -1 <-> +1 in x, y, and z. So, a perspective matrix is basically designed...
LibGDX - perspective camera smooth translation & direction
java,3d,libgdx,opengl-es-2.0,perspectivecamera
I would use the Univesal Tween Engine, which is a library for interpolating pretty much anything. You'd have to write a Vector3Accessor class (which would be very simple), but then you'd have all sorts of controls and options for smooth movement. It has a very rich API and is used...
A bit about 3D perspective projection & matrix transforms
matrix,3d,camera,rendering,perspectivecamera
First, A little explanation In standard 3d APIs , there are three transformations called : WorldMatrix , ViewMatrix and projection matrix. first has nothing to do with camera, it is about transforming the world(local world of an object) to put it in right rotation and translation. Now about the second...
Java findHomography transform image point to ground plane point
java,opencv,homography,perspectivecamera
I can't really interpret your code, especially your points but I don't think it matters because as you said your objective is to create a homography matrix from 2 sets of points and perspectively transform an image with the resulting homography matrix. Iterating through the homography matrix First of all...
OpenGL Frustum Pedagogy
opengl,geometry,glsl,linear-algebra,perspectivecamera
You are right in the sense that there is just some affine, linear transformation and no real perspective distortion - when you just interpret the clip space as a 4-dimensional vector space. But the clip space is not the "end of it all". The perspective effect is a nonlinear transformation...
Determine camera pose?
c++,opencv,computer-vision,camera-calibration,perspectivecamera
Okay, so solvePnP() gives you the transfer matrix from the model's frame (ie the cube) to the camera's frame (it's called view matrix). Input parameters: objectPoints – Array of object points in the object coordinate space, 3xN/Nx3 1-channel or 1xN/Nx1 3-channel, where N is the number of points. std::vector<cv::Point3f> can...
How to rotate a THREE.PerspectiveCamera around on object
javascript,math,rotation,three.js,perspectivecamera
As gaitat mentioned, trackball controls are the best place to start with many configurable parameters to make camera rotation/revolution easy. One enormous potential benefit of this method ( especially for your project ) is avoiding "gimbal lock" which is the source of much frustration when working with rotations. Here's a...
How to set a specific eye point using perspective view with matrices
c++,opengl,matrix,shader,perspectivecamera
In OpenGL there are three major matrices that you need to be aware of: The Model Matrix D: Maps vertices from an object's local coordinate system into the world's cordinate system. The View Matrix V: Maps vertices from the world's coordinate system to the camera's coordinate system. The Projection Matrix...
Projection Matrix yielding incorrect results
c++,opengl,math,perspectivecamera,glm-math
GLM takes the FOV angle in radians, while the value you pass (45.0) is in degrees. The GLM documentation for the parameter is about as unclear as it could be: Specifies the field of view angle, in degrees, in the y direction. Expressed in radians. Yes, that both says that...
Perspective projection seems wrong, closer parts of a model appear smaller and vice versa
directx,directx-11,perspectivecamera,projection-matrix,assimp
Your near and far plane distances should be positive. Use something like: mProjection = XMMatrixPerspectiveFovLH(XMConvertToRadians(45.0f), 800.0f / 600.0f, 0.1f, 10.0f); I'll make a note to consider adding assert( NearZ > 0.f); assert( NearZ < FarZ ); to those DirectXMath functions and make sure that's explicit in the docs. distance means...