newmap = []

    m = elevation_map
    for i in range(0, len(elevation_map)-1, 2):
        newmap.append([])
        for j in range(0, len(elevation_map[i]), 2):
            if len(elevation_map) % 2 == 0:
                s = m[i][j]
                s += m[i][j+1]
                s += +m[i+1][j]
                s += m[i+1][j+1]
                newmap[-1].append(int(s/4))
            else:

                s = elevation_map[i][j]
                s += elevation_map[i+1][j]
                newmap[-1].append(int(s/2))

                if in_matrix(elevation_map,[i,j+1]):