General Recommendations for Caching

Before starting to calculate a cache have a look through the following hints and tips regarding several caching options.

Tiling Scheme

Depending on the WebOffice 10.9 R3 project and its use cases it is important to decide which tiling scheme the WebOffice 10.9 R3 project and its caches should use. In general, there are two options for tiling schemes:

Use a custom tiling scheme that is specified exactly for the needs of your WebOffice 10.9 R3 project. You could either create a new one or simply use an existing tiling scheme (e.g. from a previously created map cache).

Use the ArcGIS Online/Bing Maps/Google Maps tiling scheme whenever you are planning to make use of any external services like, e.g ArcGIS Online, OpenStreetMap, etc. One advantage of the ArcGIS Online/Bing Maps/Google Maps tiling scheme is that it is widely known in the web mapping world, so your tiles will match those of other organizations that have used this tiling scheme.

 

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In case you are planning to use the ArcGIS Online/Bing Maps/Google Maps tiling scheme, be sure to use the coordinate system WGS 1984 Web Mercator (Auxiliary Sphere).

Tile Format

Setting the correct tile format is important to reduce the size on disk of the tiles to a minimum but also determines the quality of the images and their ability to make the tile background transparent. Before calculating the cache, review your data since the type (vector, raster or mixed) becomes important when choosing the tile format. See the table below to have a firm overview about the various tile formats:

 

Tile Format

Description

Best for

PNG

For each tile, this format picks the PNG bit depth that will minimize tile storage space without sacrificing visual quality. Try this first if you are not sure which PNG format to use.

Vector maps few colors, maps with large areas of one color, overlay networks

PNG8

Use this format for overlay services such as roads and boundaries with a transparent background with less than 256 colors. This tile format needs very small size on disk, but you will get better results with PNG32 in terms of antialiasing.

Overlay services with less than 256 colors that need transparent background

PNG24

Similar to PNG8 but supports more colors, for best quality use PNG32

Overlay services with more than 256 colors that need transparent background

PNG32

Use PNG32 for overlay services that need a transparent background and antialiasing enabled on lines or text. The created tiles are larger on disk than PNG8 and PNG24

Overlay services with many colors, antialiasing and transparencies

JPEG

Use JPEG for any basemaps that have large color variation and do not need transparencies. JPEG is a lossy image format, regulate the amount of loss through the compression (e.g. raise to 85%). Creates very small tile sizes on disk

Aerial images or any other raster imagery without transparency

MIXED

When a mixed cache is created, PNG 32 tiles are created anywhere that transparency is detected (in other words, anywhere that the data frame background is visible). The rest of the tiles are built using JPEG. This keeps the average file size down while providing you with a clean overlay on top of other caches.

Maps that use vector and raster data where transparency is also needed

Tiling formats

 

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Image formats are responsible for the size of a map cache tile. Consider that a PNG32 will take much longer to be displayed as a PNG8 cache tile.

 

If you are not sure which tiling format to choose and you want to know the size on disk, use the option Calculate Cache Size to get an estimated cache size.

 

Service Editor - caching

Service Editor - caching

Storage Format

There are two different storage formats to choose from:

Compact: In compact format, each file in the cache contains a bundle of tiles.

Exploded: In exploded format, each tile is stored as a file on disk.

In general compact caches are easier to handle, since they take less space on disk and are much faster to create and to copy. This is especially important when using a staging system where copying data from one system to another is necessary. Only if the points prior to this are not crucial, then use exploded cache for best performance.

 

Service Editor - advanced cache settings

Service Editor - advanced cache settings

 

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Be sure not to change the predefined Origin (x, y) in map units. A far from map content positioned cache origin is needed and does not mean a generation of many empty tiles outside the defined cache extent.