I have 4 2D points in screen-space, and I need to reverse-project them back into 3D space. I know that each of the 4 points is a corner of a 3D-rotated rigid rectangle, and I know the size of the rectangle. How can I get 3D coordinates from this? I am not using any particular API, and I do not have an existing projection matrix. I'm jus...
I saw a question on reverse projecting 4 2D points to derive the corners of a rectangle in 3D space. I have a kind of more general version of the same problem: Given either a focal length (which can be solved to produce arcseconds / pixel) or the intrinsic camera matrix (a 3x2 matrix that defines the properties of the pinhole camera mo...
What is the simplest way to un-warp a photo made using fisheye or wide-angle lens? I'm looking a pixel projection formula that has few parameters. Camera and lens parameters will not be known, so user has to change the parameters visually. Thanks ...
Related to my previous question, is there some realistic chance to extract surveillance camera positions out of google streetview pictures by means of computer vision algorithms? I'm no expert in that area. But it should be easier than face detection and the like. ...
Given a picture taken by a simple digital that contains an image of a rectangle of known dimensions. How can I - to some degree of accuracy - determine the parameters of this camera? I am mostly interested in Pan-, Tilt- and Swing angles. Optionally distance to the rectangle would be nice. I acknowledge the fact that the focal length ...
As a followup to my previous question about determining camera parameters I have formulated a new problem. I have two pictures of the same rectangle: The first is an image without any transformations and shows the rectangle as it is. The second image shows the rectangle after some 3d transformation (XYZ-rotation, scaling, XY-translati...
I'd like to create a Photosynth like experience that allows a user to navigate around a virtual environment from a collection of many pictures. For this project I'm limited to using WPF / .NET to create the application. Ideally I'd like a Photosynth component that I could drop in my application - is anything like that available? ...
hi, i have .las (lidar data) file, now i wanted to know the size of it, for example how long it's width and height in kilometers... how is it possible to retrieve these kind of info? thanks a lot!!! ...
I’m working on creating a full-screen 3-D app (based on Johnny Lee's Wii head tracking app) with some augmented reality features, and it seems that WPF is too slow to render even the simple models I’m using at a reasonable frame rate. I think the problem is that I need to change both the view and projection of the camera on just about ev...
I want to know the depth of field of a photo, preferably in cm or m. I know that we can know the camera setting by reading the EXIF tags, but is there a tag directly telling us the depth of field? Or how can we calculate it from some EXIF tags? Examples would be appreciated. Thanks! ...
Heyguys.. This isn't exactly a programming question exactly. I just want to know what your approach would be to a common problem in Digital image processing. Lets say you have an image of a a few trees in say jpg format. How would you go about finding the heights of each of these trees. The photo is the only input you have. I want to ...
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 pl...
Hi, I'm searching for a library similar to ARToolKit. It needs to support processing a single image and search that image for a marker. If it finds one I want it to return the camera angle / viewpoint based of the marker. I couldn't find anything via Google, does something like this exist? ...
Hi, I uploaded an example image for better understanding: http://www.imagebanana.com/view/kaja46ko/test.jpg In the image you can see some scanlines and a marker (the white retangle with the circle in it). I want opencv to go along a specified area (in the example outlined trough the scanlines) that should be around 5x5. If that area co...
I have a number of images where I know the focal length, pixel count, dimensions and position (from GPS). They are all in a high oblique manner, taken on the ground with commercially available cameras. What would be the best method for calculating the euclidean distances between certain pixels within an image? If it is indeed possible...
I'm counting objects in an image. I wish to perform a linear interpolation where I know the pixel sizes of my objects at near and far perspectives and the positions of these two objects in the image. The images at the bottom of the image are larger as they are near the camera which took them. The image to be analysed is the same from t...