The source code for the Map Builder demonstration, which contains
all of the code described in this section, can be found at <installdir> /jviews-maps810/samples/mapbuilder/index.html
All raster (image) data sources have a common API. To create your
data source, you need to create an IlvRasterAbstractReader for the type of data
to be read, and then use this reader to build a tiled image data
source.
Raster reader classes
The raster reader classes for the
different image formats are as follows.
GEOTIFF IlvRasterGeoTiffReader DTED IlvRasterDTEDReader GTOPO30 IlvGTopo30Reader Non-geo-referenced images(*) IlvRasterBasicImageReader Images from OpenGIS compliant Web Map Servers IlvWMSReader
(*) Non georeferenced images must be geo-referenced, see Georeferencing a nongeoreferenced image.
Creating a raster reader
To create a raster reader and add all
image files to be read you can, for example, use the following
code:
Creating a tiled data source
To create a data source for the reader:
IlvRasterDTEDReader reader = new IlvRasterDTEDReader();
for(int i=0;i<fileName.length;i++) {
reader.addMap(fileName[i]);
}
IlvMapDataSource DTEDDataSource =
IlvRasterDataSourceFactory.buildTiledImageDataSource(manager,reader,true,true,null);
DTEDDataSource.setName("name in data source panel");
The IlvTiledRasterDataSource returned by the IlvRasterDataSourceFactory executes image
reading in a background thread.
Georeferencing a nongeoreferenced image
To georeference a nongeoreferenced image,
you can set the longitude and latitude image bounds:
reader.setImageBounds(0,-Math.PI,Math.PI/2,Math.PI,-Math.PI/2);
Alternatively, you can compute a more
complex mathematical transformation and set it on the reader:
reader.setInternalTransformation(trans);
Note
The non georeferenced image reader does
not support multiple calls to addMap.
Images from OpenGIS-compliant Web Map Servers
This section gives information about the OpenGIS® Web Map Server (WMS standard). This International Standard
specifies the behavior of a service that produces spatially
referenced maps dynamically from geographic information. It
specifies operations to retrieve a description of the maps
offered by a server and to query a server about features
displayed on a map. The standard is not applicable to the
retrieval of actual feature data or coverage data values, but is
applicable to pictorial renderings of maps in a graphical format.
These capabilities are provided by a Web Feature and Web Coverage
Service.
In a basic WMS, only a limited number of
predefined styles can be applied to features. The mechanism that
enables users to define their own styles is defined in the OGC
Styled Layer Descriptor Implementation Specification. An
SLD-enabled WMS retrieves feature data from a Web Feature Service
and applies explicit styling information provided by the user in
order to render a map.
The ISO/TC 211 also defines a standard for Web Map Servers, see ISO
19128.
Importing a WMS image
JViews Maps supports
the import of images from a WMS server.
To create a WMS data source, use the
following code:
URL url = new URL("http://geo.compusult.net/scripts/mapman.dll?
Name=weather&REQUEST=GetCapabilities");
IlvWMSReader reader = new IlvWMSReader(url);
IlvWMSDataSource source = new IlvWMSDataSource(reader);
source.setManager(manager);