A method for composing an output video signal (S o), which comprises an output frame sequence (S o [n]) with a pre-established number of pixels for each output frame associated with an output resolution (R o) from a plurality of input video signals (S i1, S i2, S i3... S im) comprising respective input frame sequences (S i1 [n], S i2 [n], S i3 [n]... S im [n]) with a number of pixels for each input frame associated with an input resolution (R i1, R i2, R i3... R im), which comprises: a configuration step in which a spatial surface on a three-dimensional virtual space is determined, formed by a set of points with three-dimensional coordinates (X,Y,Z) associated with each pixel (p) of each frame of each input frame sequence (S i1 [n], S i2 [n], S i3 [n]... S im [n]); establishing in the three-dimensional virtual space a visualization point (X 0,Y 0,Z 0) and a visualization window, which determine a visualization frustum in the three-dimensional virtual space, and forming output frames (S o [n]) from the projections of the input frames (S' i1 [n], S' i2 [n], S' i3 [n]... S' im [n]) of the input sequences projected in said visualization window; wherein the method also comprises: calculating a threshold pixel density (d(S' o [n])) associated to the pixels in the visualization window, from the output resolution (R o) and the associated spatial dimensions of said visualization window; determining combinations of input frames, the projections (S' i1 [n], S' i2 [n], S' i3 [n], S' i4 [n]) of which are at least partially overlapping in the visualization window and, for each combination of frames, selecting the frame of each combination of input frames, which projected on the visualization window has a pixel density d(S' i1 [n]), d(S' i2 [n]), d(S' i3 [n]), d(S' i4 [n]) in the entire overlapping part greater than or equal to the threshold pixel density (d(S' o [n])) or, in the absence thereof, selecting the input frame which projected on the visualization window has the pixel density closest to the threshold pixel density for forming the output frame (S o [n]) part which is overlapping. a configuration step in which a spatial surface on a three-dimensional virtual space is determined, formed by a set of points with three-dimensional coordinates (X,Y,Z) associated with each pixel (p) of each frame of each input frame sequence (S i1 [n], S i2 [n], S i3 [n]... S im [n]); establishing in the three-dimensional virtual space a visualization point (X 0,Y 0,Z 0) and a visualization window, which determine a visualization frustum in the three-dimensional virtual space, and forming output frames (S o [n]) from the projections of the input frames (S' i1 [n], S' i2 [n], S' i3 [n]... S' im [n]) of the input sequences projected in said visualization window; wherein the method also comprises: calculating a threshold pixel density (d(S' o [n])) associated to the pixels in the visualization window, from the output resolution (R o) and the associated spatial dimensions of said visualization window; determining combinations of input frames, the projections (S' i1 [n], S' i2 [n], S' i3 [n], S' i4 [n]) of which are at least partially overlapping in the visualization window and, for each combination of frames, selecting the frame of each combination of input frames, which projected on the visualization window has a pixel density d(S' i1 [n]), d(S' i2 [n]), d(S' i3 [n]), d(S' i4 [n]) in the entire overlapping part greater than or equal to the threshold pixel density (d(S' o [n])) or, in the absence thereof, selecting the input frame which projected on the visualization window has the pixel density closest to the threshold pixel density for forming the output frame (S o [n]) part which is overlapping. calculating a threshold pixel density (d(S' o [n])) associated to the pixels in the visualization window, from the output resolution (R o) and the associated spatial dimensions of said visualization window; determining combinations of input frames, the projections (S' i1 [n], S' i2 [n], S' i3 [n], S' i4 [n]) of which are at least partially overlapping in the visualization window and, for each combination of frames, selecting the frame of each combination of input frames, which projected on the visualization window has a pixel density d(S' i1 [n]), d(S' i2 [n]), d(S' i3 [n]), d(S' i4 [n]) in the entire overlapping part greater than or equal to the threshold pixel density (d(S' o [n])) or, in the absence thereof, selecting the input frame which projected on the visualization window has the pixel density closest to the threshold pixel density for forming the output frame (S o [n]) part which is overlapping.