I got images of a rectangular robot moving in a large room, the images are taken by a standing person, and so perspective changes the distances between robot and its environment. I need the right distances. So, I want to cure the effect of perspective (in other words now vertical parallel lines are meeting in some far point, I want vertical parallel lines to be always parallel).

I think if I had a tool to resize a usual rectangular image to any arbitrary 4 sided shape, I could do it...
Example: image edge lengths are, say, starting by the left one, in the clockwise direction, 480,640,480 and 640. Now I want to warp/resize it so that, each edge should get the arbitrary lengths I want, for example, 480, 640, 560, 720. And all the inside pixels should move appropriately. Does inkscape has such tool?

or any other recommendations?

thx....

I know that it is very easy to do in raster image editors, as they typically allow you to distort images in almost any way. Fireworks could also distort the perspective look for both raster and vector (as I recall).

Unfortunately, Inkscape doesn't seem to allow you to stretch a single edge. Your best bet with Inkscape would be to manually move the points. You could also open up the SVG file and, using some sort of formula, adjust each point based on the coords of the vanishing point. If the image is as complex as I suspect it is, manual is really your only option anyway.