Updated 12/08/09: We changed the level numbers to account for the fact that we will not have the need for the coarsest scales (see M1-M5 below where M stands for'Minus'). Also, the cach MXD has been updated
In the first round of caching, we generated 691,000 .jpg tile files which took up 55 GB of disk space. This did not include any caching at the finest scale levels (14 & 13) as these are programmed to be cached on demand.
Our strategy attempts to follow the tile-caching scales utilized by Google and Microsoft online maps. In addition we have created breakpoints between these tile scales for use with dynamic maps. Think of the breakpoints as the list of potential scale dependencies that can be used for the upper and lower scale criteria.
AGRC Level
Google Tile Scale
Break Point
14
1128.50
1500
13
2256.99
3000
12
4513.99
6250
11
9027.98
12500
10
18055.96
25000
09
36111.91
50000
08
72223.82
100000
07
144447.64
200000
06
288895.29
400000
05
577790.58
800000
04
1155581.15
1600000
03
2311162.31
3500000
02
4622324.61
7000000
01
9244649.23
14000000
00
18489298.45
25000000
M1
36978596.91
50000000
M2
73957193.82
100000000
M3
147914387.60
200000000
M4
295828775.30
400000000
M5
591657550.50
Users' Comments
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1.
Wed, 11-26-2008 at 05:44 PM
Level 00 - 04,18 and 19 are cache on demand scale levels. Which means they aren't cached until someone requests them. This strategy is used to cut down on server disk space and cache creation time. What it translates to is we aren't going to cache the center of the great salt lake below 1 : 4513 unless someone wants to look at it.