Re: Follow point in AVI
- To: mathgroup at smc.vnet.net
- Subject: [mg123936] Re: Follow point in AVI
- From: Mark McClure <mcmcclur at unca.edu>
- Date: Mon, 2 Jan 2012 02:39:20 -0500 (EST)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <201112301206.HAA08399@smc.vnet.net>
On Fri, Dec 30, 2011 at 7:06 AM, nlko <niko at homebound.de> wrote: > I want to follow a horizontal movement of a black object on white > background in an AVI. It just so happens that I need to solve a similar question. Here's a very short clip of a flying saucer from The Day the Earth Stood Still. movie = Import["http://facstaff.unca.edu/mcmcclur/Saucer.mov";, "GraphicsList"]; ListAnimate[Image /@ movie] We can find the location of the ship using Binarize. In this case, we've got to block out the bottom since the white building has a color similar to the ship. This is accomplished using ImageMultiply with a black bottomed image. marker = Image[Join[Table[1, {100}, {480}], Table[0, {260}, {480}], 1]]; binaryMovie = Table[Binarize[ImageMultiply[frame, marker], 0.9], {frame, movie}]; Let's check how it worked. ListAnimate[binaryMovie] If you need something like a center of mass, I guess you do to the following. locations = Table[ Mean[N[Position[ImageData[frame], 1]]], {frame, binaryMovie}]; locations = {#[[2]], 360 - #[[1]]} & /@ locations; Here's a look. ListAnimate[Image /@ Table[Graphics[Point[loc], PlotRange -> {{0, 480}, {0, 360}}], {loc, locations}]] Mark McClure