ESRI shapefiles

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Revision as of 15:32, 27 October 2005

ESRI shapfiles or shapefiles are a common format for storing GIS related information. Basic shapefile support is included with World Wind.

Adding shapefiles to World Wind

Adding shapfiles to World Wind is currently a simple manual process. A user interface will be added in a future version of World Wind.

In your main World Wind folder (eg C:\Program Files\NASA\World Wind 1.3\) there is a folder named ShapeFiles. You must create an xml file for your shapefile in that folder. Your shapefile files go in a folder beneath that.

Complete documention is still being written, however it's a simple process and you can use these sample shapefiles to get an idea of how it works.

Until the documentation is written, here are a few notes on the contents of the XML file:

An XML file appears as its own top level in the Layers menu.
An XML file lists one or more layers, each of which may be turned on or off. If you have only one layer, it should be pre-selected (ShowAtStartup="true").
An XML file may specify that only one layer should be shown at a time (ShowOnlyOneLayer="true")
An XML file may default to being turned on when WW starts (ShowAtStartup="true")
It can describe multiple layers derived from one or more shapefiles. Each view requires its own ShapeFileDescriptor section containing one or more of the following elements:

 * Name - the name visible to the user in the Layers menu underneath the LayerSet's name.
 * ShapeFilePath - the path, starting at the WW directory, to the shapefile.
 * DataKey - the key of the data in the shapefile's dbf file.
 * NoDataValue - the value to use when an element (point, line, polygon) has no data for that key.
 * ShowLabels - true or false if the data should be shown as a label.
 * PolygonFill - true or false if polygons should be filled.
 * OutlinePolygons - true or false if Polygons should be outlined.
 * PolygonColor - contains three elements: Red, Blue, and Green, integer values between 0 and 255.
 * LineColor - contains three elements: Red, Blue, and Green, integer values between 0 and 255.
 * LabelColor - contains three elements: Red, Blue, and Green, integer values between 0 and 255.
 * LineWidth - contains a floating point number describing the width of the line in pixels.
 * ScaleColorsToData - polygons are filled with a color proportional to the data.
 * ScalarMin and ScalarMax determine which values will be assigned to the lightest and darkest colors.

Not all shapefile types are supported. These are: Points, Arcs (aka PolyLine), and Polygons. Multipoints are not. Also, (currently) if a shapefile contains Arcs with zero or one points, WW will not render any arcs out of that file.