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2017-07-07 09:15:51 -0600	received badge	● Teacher (source)
2013-05-28 04:16:02 -0600	commented answer	2D pixel coordinate to 3D world coordinate conversion I have updated my answer.
2013-05-28 04:04:37 -0600	received badge	● Editor (source)
2013-05-27 02:52:02 -0600	answered a question	2D pixel coordinate to 3D world coordinate conversion During the transformation from 3D to 2D you are losing the depth information. All you can do with the matrices that you have, is to transform a 2D pixel into a 3D line where every point on this line would be projected onto the same 2D pixel. You will definitely need additional information to reconstruct a 3D point. For example an additional view of the same scene at the same time (stereo vision). EDIT The homography transforms one plane in 3D space into another plane in 3D space. You cannot get absolute coordinates from this, because the homography is not unique. You can get some information from a single view, if you have some additional information about the view (if you have a calibration object in the view, or if you can use structured lighting, etc.) I recommend searching for "single view geometry" and if you want to read an excellent book on this topic, I recommend "Multiple View Geometry in Computer Vision" by Hartley & Zisserman, which also has a chapter about single view geometry.
2013-05-27 02:23:19 -0600	answered a question	How to compute distance to car ahead using camera. OpenCV can definitely be used to solve this problem, but first you need to be able to formulate an algorithm to estimate the depth from a single camera. Humans have two eyes for a reason :-) Unfortunately I cannot help you in that department, but I will refer you to this Wikipedia page. You may also look for android augmented reality sdk. Hopefully this will point you in the right direction to find solutions that are sufficient for your application. To clarify: OpenCV is an image processing (computer vision) library, that is used through the Android NDK. Android NDK stands for Android Native Development Kit, which allows you to mix machine code and Dalvik byte code.
2013-01-28 05:14:06 -0600	received badge	● Supporter (source)
2012-12-10 04:40:28 -0600	commented question	Apply notch filter on image What is your question?
2012-12-10 04:35:36 -0600	answered a question	OpenCV Crash Issue when using in xcode You need to change `for(int i=0;iheight;i=i++)` to `for(int i=0; i < img->height; i++)` and `for(int j=0;jwidth;j++)` to `for(int j=0; j < img->width; j++)`. `<img->` was incorrectly identified as a HTML tag and because the browser does not understand that tag, it ignores it. Generally, you should try to understand the source code, that you are trying to compile :-). BTW: In case of inexplicable crashes: Assume, you are accessing a resource, that has not been initialized yet. Prove the assumption to be wrong. Assume, you are accessing an array beyond its bounds. Prove the assumption to be wrong. ...