Size of tile pyramid

pyramid_size.py

from math import log, ceil, sqrt

# Gennemsnitlig stoerrelse af en tile. 25kB passer nogenlunde med ortofoto
size_per_tile = 25 * 1024 # 25kB



# --------GSTs standard skema ---------------
# Koordinater paa tilet omraade (xmin, ymin, xmax, ymax)
#bbox = [120000, 5900000, 1000000, 6500000]
# Pyramidens oploesninger
#[1638.4, 819.2, 409.6, 204.8, 102.4, 51.2, 25.6, 12.8, 6.4, 3.2, 1.6, 0.8, 0.4, 0.2, 0.1]
#top_res    = 1638.4
#bottom_res = 0.05
#res_factor =  sqrt(2)

# -------Box indsnaevret til at daekke Jylland og Sjaelland
# Koordinater paa tilet omraade (xmin, ymin, xmax, ymax)
bbox = [430000, 6040000, 750000, 6400000]
# # Pyramidens oploesninger
top_res    = 1638.4
bottom_res = 0.1
res_factor = 2 #sqrt(2)

# ==============================================================================

def resolutions(maxres, minres, factor):
  res = maxres
  z = 0
  # Allow small numeric error
  while res > (minres - minres * 0.001 * factor):
    yield res
    z = z + 1
    res = maxres / (factor ** z)

unit_list = zip(['bytes', 'kB', 'MB', 'GB', 'TB', 'PB'], [0, 0, 1, 2, 2, 2])
def sizeof_fmt( size_bytes ):
    """Human friendly file size"""
    if size_bytes > 1:
        exponent = min(int(log(size_bytes, 1024)), len(unit_list) - 1)
        quotient = float(size_bytes) / 1024**exponent
        unit, num_decimals = unit_list[exponent]
        format_string = '{:.%sf} {}' % (num_decimals)
        return format_string.format(quotient, unit)
    if size_bytes == 0:
        return '0 bytes'
    if size_bytes == 1:
        return '1 byte'
        
def wmts_scaledenom( resolution ):
  return resolution / 0.00028

res = list( resolutions(top_res, bottom_res, res_factor) )
bboxsize = (bbox[2] - bbox[0], bbox[3] - bbox[1])
print "BBoxsize: ", bboxsize, "m, Area: ", bboxsize[0] * bboxsize[1] / (1000 * 1000), "km2"
print "Average tile size: ", sizeof_fmt( size_per_tile )
print "Resolutions: ", res, "m/pixel"

tiles = 0

for z, r in enumerate(res):
  size_m = r * 256

  tilesw = int(ceil( bboxsize[0] / size_m ))
  tilesh = int(ceil( bboxsize[1] / size_m ))
  lyrtiles = tilesw * tilesh
  tiles = tiles + lyrtiles

  print "  Zoom: ", z, ", Resolution: ", r, "m, Tile size: ", size_m, "m, WMTS ScaleDenominator", wmts_scaledenom( r )
  print "     Dimensions: ",tilesw, "x", tilesh, " tiles"
  print "     Tiles: ", lyrtiles
  print "     Size: ", sizeof_fmt(lyrtiles * size_per_tile)
  print "     Accum size: ", sizeof_fmt(tiles * size_per_tile)
print "Tiles: ", tiles
print "Size: ", sizeof_fmt(tiles * size_per_tile)