bogart@utah-gr.UUCP (11/18/87)
I am attempting to solve a view correlation problem. Given a set of 3D points and the 2D coords of each from a photo image, find all the parameters necessary to render (or raytrace) the points and get the same 2D coordinates. For example, I have a photo of an object which I know to be a cube. I can assign 3D coords to the corners of the box, then find the locations of each corner in the image. I would like to throw all of that data at a black box, and get back the viewpoint, view direction, aspect ratio, etc. So far, I have tried solving this using methods from Rogers "Mathematical Elements for Computer Graphics" and various Utah theses. All of the solutions seem to very unstable numerically, i.e. if the the points are ordered differently, I get a different solution. This is because these methods attempt to solve a system of equations that is rather large, and the math breaks down if there is error in the original data. I suspect that an iterative technique would be more suitable, but I have no references for one. Any help out there? I would greatly appreciate mail from anyone who has actually written code to solve the problem, but feel free to send any references, suggestions or ideas that seem appropriate. RGB (Yeah, those are my real initials...) bogart@cs.utah.edu
webber@brandx.rutgers.edu (Webber) (11/21/87)
In article <2234@utah-gr.UUCP>, bogart@utah-gr.UUCP (Rod G. Bogart) writes: > I am attempting to solve a view correlation problem. Given a set of > 3D points and the 2D coords of each from a photo image, find all the > parameters necessary to render (or raytrace) the points and get the same 2D > coordinates. > > For example, I have a photo of an object which I know to be a cube. I > can assign 3D coords to the corners of the box, then find the > locations of each corner in the image. I would like to throw all of > that data at a black box, and get back the viewpoint, view direction, > aspect ratio, etc. > ... > Any help out there? I would greatly appreciate mail from anyone who > has actually written code to solve the problem, but feel free to send any > references, suggestions or ideas that seem appropriate. ref: ``A Montage Method: the overlaying of the computer generated images onto a background photograph,'' Eiharchiro Nakamae, Koichi Harada, Takao Ishizaki, and Tomoyuki Nishita, SIGGRAPH'86 (Computer Graphics, v20 #4, August 1986), August 18-22 1986, Dallas Texas, 207-214. They have an appendix showing how to locate viewpoint (and other camera features of a photo) using least squares. The overall application was to take a photograph of a town and a computer model of a bridge or building and show people what the aesthetic impact of the proposed construction will be on the town. ----------- BOB (webber@athos.rutgers.edu ; rutgers!athos.rutgers.edu!webber)