Just another WordPress.com site

The Exponential Nature of Tiled Maps



The Tiled method of providing basemap images to an application has mountains of benefits to the user.  These benefits are not cheap or easy, however, for those involved in creating and providing those tiled images.  To cover a geographic area at increasing zoom levels (or increased resolution), nested sets of tiles must be created; each additional zoom-level consisting of 4 times the number of tiles from the previous zoom level.

For example, Virtual Earth requires four 256 x 256 tiles to represent the world at zoom-level 1.  At zoom-level 2, sixteen tiles are required to cover the same geographic extent.  Since there are more images, the level of detail increases (i.e., it looks like you are zooming in and things are getting bigger).  Here is a chart that illustrates how quadrupling the number of required tile images per zoom-level quickly requires an exponentially large set of tiles.  This is just for the first four zoom-levels…

Tiles Per Zoom-Level

Here is a series of images to illustrate resolution changes per zoom level and the number of tiles required at each to cover the same geographic extent (the yellow box in the corner is a preview area for the geographic area covered by one tile at the next zoom-level).  This first 256 x 256 tile image shows the region around New Orleans/Lake Pontchartrain.  At the next zoom-level, that same geographic area is split into four individual 256 x 256 tile images to provide greater detail.  Again, each additional zoom-level has quadruple the number of tiles as the previous zoom-level.

 Tile 1; the region around New Orleans/Lake Pontchartrain.

 4 tiles (to cover the same geographic extent as the image above).

 16 tiles.

 64 tiles.

 256 tiles.

 1,024 tiles.

 4,096 tiles.

 16,384 tiles.

 65,536 tiles.

 262,144 tiles.

 1,048,576 tiles.

 4,194,304 tiles.

 16,777,216 tiles (to cover the same geographic extent as that top image).


How Many Tiles??

That pool up there is at Virtual Earth’s zoom-level 20.  That’s pretty amazing.  If VE had individual tiles for the whole world at this resolution (which they don’t), they would need 366,503,875,924 tiles per map style!  Here’s how it breaks down per zoom-level…


John Nelson / IDV Solutions / john.nelson@idvsolutions.com



2 responses

  1. Unknown

    Thank you .
    31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

    August 31, 2008 at 8:28 am

  2. Unknown

    adapter laptop

    toshiba 15V 6A 90w 6.3mm*3.0mm adapter PA2501U PA2521U PA3201U-1ACA
    toshiba 15V 8A 120w 6.3mm*3.0mm adapter PA3201U-1ACA SEB100P2-15
    toshiba 15V 8A 120w special 4 hole adapter PA3237U-1ACA PA3237U
    toshiba 19V 3.42A 65w 5.5mm*2.5mm adapter PA3467U-1ACA PA3396U-1ACA
    toshiba 19V 3.16A 60w 5.5mm*2.5mm adapter PA3097U-1ACA
    toshiba 19V 4.74A 90w 5.5mm*2.5mm adapter PA-1750-04

    toshiba 19V 4.74A 90w 6.3mm*3.0mm adapter PA3201U-1ACA SEB100P2-15.0
    toshiba 19V 6.3A 120w 6.3mm*3.0mm adapter PA3290U-1ACA
    toshiba 19V 6.3A 120w 5.5mm*2.5mm adapter PA3290U-2ACA PA-1121-08
    universal 12-20V 90W universal adapter laptop
    universal 12-20V 120W universal adapter laptop
    universal 12-20V 70W universal adapter laptop

    October 13, 2008 at 4:58 am

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s