The rotation matrix is right-handed, with x pointing in flight direction, y to the right and z down. The algorithm to compute the position of one pixel on the ground is (adapted to use an LSR system, one might do it with geographic coordinates as well): public void ImageToGround(Camera sensor, double posx, double posy, double posz,ĭouble groundheight, out double resultx, out double resultx) Example values for a typical medium format camera for aerial mapping would be 50mm focal length, 9000*6800 pixels, with 6microns pixel size, giving ~40x54mm image size. If I'm saying the "real" size of the image that really means the size of the image (or maybe, easier imaginable, the size of the negative of a classical film camera). First, we need to know the physical characteristics of the camera, that is focal length and real size of the images it takes, together with the size in pixels. I'll try to give an overview over the algorithm used to solve this kind of problem. If you need more information please let me know. (x2,y2) may not be in the centre of the captured surface and also there is some kind of offset that needs to be added to the coordinates since the captured surface is not directly below.
My first attempt was to get the size of the surface that is in view, then use that to scale my coordinates. If I could manage something that works reasonably well for even just 40 degrees from vertical, that would be great. Clearly this means that the distance between 2 pixels at the furtherest away parts of the image is greater than the distance between the closer pixels which are 'magnified' in a sense. The more horizontal the camera points, the more surface is going to be in view of the image. I understand that this could get very complicated. each of the outer lines are (1/2)a degrees from the centre one. The centre line (the one which ends at (x2,y2) bisects the 2 other lines i.e. The problem is if the camera was at an angle. This is fine from directly above a point, I can just scale my coordinates by some factor calculated using basic trigonometry. So what I'm trying to do, is map coordinates on an image taken from the sky, to a coordinate on a flat surface on the ground. I've been at it for a long time now and I would appreciate if someone could give me some direction. I have this issue which I have possibly overcomplicated in my head.
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