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The most important challenge for web-mapping applications is the reducing of the size of downloaded data. The aim is the setting up each packet of data as small as possible. The ALOV Map gives you all means to design your project in proper way. You have to strive to define your project in order that the size of initial packet of data will be in range 50-150KB and the next packets - 10-50KB.
To reduce initial packet you may switch off the initial visibility of unimportant and high-resolution layers.
<![CDATA[
<layer name="Main roads" visible="yes">...</layer>
<layer name="Other roads" visible="no">...</layer>
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Zoom Layering allows you to set the minimum and maximum distances at which a layer is visible. This is particularly useful if you have an high-resolution layers. It is not effective to download and to see all these data at once. Set the zoom layer to display the generalized maps first and detail maps only when the map zoom level is within a particular range.
<![CDATA[
<layer name="Countries" zmin="2500">...</layer>
<layer name="States" zmax="2500" zmin="1000">...</layer>
<layer name="Counties" zmax="1000">...</layer>
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The zoom range values must be set in project's zoom units.
There are two types of units in project: map units and zoom units. Map units are the units in which the coordinates of the spatial data contained in your map are stored. It is important to determine what map units your spatial data is stored in. IMPORTANT: All data added in your project MUST BE the same coordinate system and map units.
Map Units setting is independent of its Zoom Units setting. Zoom units are the units used to display the current map extent or set up zoom ranges for layers.
To set a project's map and zoom units define the appropriate attributes for project element.
<![CDATA[
<project zoomunits="km" mapunits="meters">
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The possible values are "degrees";"meters";"km";"inches";"feet";"miles";
"degree" is applicable for map units only. This is default value for map units. "meters" is default for zoom units.
You may set zoom ranges for whole project as well.
<![CDATA[
<project zoomunits="km" zmin="10">
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It is strictly recommended to define full project's extent (domain). Otherwise all initially visible layers are downloaded completely and its summary extent is considered as full project's domain. You see that it removes all benefits of incremental downloading of data. Define the startup domain as well. This is the additional way to reduce the initial download size.
<![CDATA[
<project name="USA" zoomunits="km" zmin="70">
<domain name="Full Map" full="yes"
xmin="-178.2176" ymin="0.20647"
xmax="-66.96927" ymax="90"/>
<domain name="East Coast" startup="yes"
xmin="-86.01414" ymin="32.64062"
xmax="-66.48508" ymax="48.42526"/>
<domain name="California"
xmin="-126.8" ymin="31.56"
xmax="-112.15" ymax="42.8" />
....
</project>
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The domain's bounds must be defined in Map units.
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