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GIS Servers and services
GIS Servers and services
Understanding map caches in ArcGIS |
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Release 9.2
Last modified March 10, 2008 |
Print all topics in : "GIS Servers and services" |
ArcGIS software uses map caches in three primary ways, and you may have encountered a reference to more than one of these. This can be confusing to understand. Which map cache is which? Which is the right one for you to use?
This topic helps to explain each of the three map caches and will point you to topics for further reading and information.
The ArcMap map cache
This map cache is used to improve performance for multiple users who access and work with ArcMap documents and data across a local area network (LAN) in their organization. The goal of the ArcMap cache is to improve performance by enabling your local machine to temporarily store features and edits in memory on your computer. The ArcMap map cache works well when you are focused on work tasks performed within a particular map area. As you redraw the map - say as you are making edits or updates - the display can be done straight from the cache instead of making another round trip across the LAN to retrieve the data each time the map re-draws.
At earlier releases of ArcGIS, this ArcMap map cache was referred to as the "edit cache" because it was used primarily to improve display and redraw performance during editing. This functionality has been generalized in recent releases to support more than editing and to cover all map redraw and navigation.
Learn more about the ArcMap map cache
The ArcGIS Server map cache
A server map cache is a collection of pre-rendered map tiles that can be used for display of a map service. This allows a map service to quickly display maps because the map image does not have to be rendered on the fly; the cost of rendering the image is paid only once when the cache is created.
The server map cache can support multi-scale maps. It does this by creating an image pyramid for your map at a series of map scales. You choose the map scales at which your map cache will be computed - say at map scales of 1:250,000, 1:100,000, 1:60,000, 1:30,000, 1:10,000, and 1:5,000. If you have used online maps at web sites such as GoogleTM Maps, Yahoo! ® Maps, or MapQuest ®, you can see fast performance for accessing maps that draw at various levels of resolution as you pan and zoom. This is the same affect that is provided by the ArcGIS Server map cache.
The server map cache greatly improves performance because the map does not need to be computed each time the user requests a map from the server. Instead, the images are retrieved from the map cache for the requested map extent and resolution. This means that ArcGIS map services can scale to very large numbers of users and maps served per hour.
Learn more about creating a server map cache
Learn more about geoprocessing tools to create and manage server caches
The ArcGIS Mobile map cache
A mobile map cache is a specialized map that is hosted on and used on a mobile device such as a smart phone or a pocket PC. These maps are optimized for the small storage capacity, low resolution, and fast interactive performance required on these devices. You load the mobile map cache on the device to take to the field.
For more information about using mobile map caches with ArcGIS Server, see help file named "Developing mobile applications using the Mobile ADF". This document is part of the ArcGIS Server developer help for Windows.