OpenJump_OSMM_GML_Mod
This repo contains a mod to enable loading Ordnance Survey MasterMap (OSMM) topographic layer GML file via OpenJump API.
OpenJump provides a mechnism to load gml via user-specified xml templates (http://ojwiki.soldin.de/index.php?title=Working_with_GML).
In a OpenJump GML template, a user can specify collection element, feature element, geometry element and define columns for various feature attributes. It seems, however, there are a few restrictions:
- Columns defined as feature element attributes are not loaded;
- Data without geometry elements can't be loaded
In case of OSMM, the attribute "fid" is defined as an attribute of feature element so it wouldn't be loaded by the original OpenJump GML reader. Also, the SRID in OSMM is "osgb:BNG" where OpenJump GML assumes a number for SRID.
To address the above issues, three OpenJump classes are modified:
-
com.vividsolutions.jump.io.GMLReader
-
com.vividsolutions.jump.io.ColumnDescription
-
com.vividsolutions.jump.io.GMLInputTemplate
There are six feature categories in OSMM topographic layer:
- TopographicArea
- TopographicLine
- TopographicPoint
- CartographicPoint
- CartographicText
- BoundaryLine
You will need a template for each category. Six sample template files for OSMM topographic layer features are provided in templates folder. All attributes are included in these templates. If you don't need all attributes for a feature category, you may simple edit the templates and remove the entries for unwanted attributes.
It should be noted that for feature attributes that allow multiple values (e.g. theme), the returned value by OpenJUMP API has type Object, which may either be a simple data value (e.g. double, String), or a list of values. Your programme needs to take this into consideration.
One issue is the textRendering attribute for CartographicText features is a complex attribute which contains four child attributes. OpenJump GML loader can't handle complex attributes so the child attributes have to be loaded individually. Below is an example of textRendering attribute value:
<osgb:textRendering>
<osgb:anchorPosition>2</osgb:anchorPosition>
<osgb:font>1</osgb:font>
<osgb:height>3.000</osgb:height>
<osgb:orientation>0</osgb:orientation>
</osgb:textRendering>
OSMM ITN contains non-geometric road to road_memeber mapping. I have a different handler for loading this mapping. Hopefully I will upload it to this repo soon.
To use this mod in your JAVA programme, please use one of the two jar files in JAR folder in place of the original OpenJump jar file. Normally a feature category in an OSMM topographic layer GML file may be read into an OpenJump FeatureCollection in the following manner:
DriverProperties dp = new DriverProperties();
dp.setProperty("TemplateFile", "your_template.xml");
dp.setProperty("DefaultValue", "your_GML.gml");
FeatureCollection fc = null;
GMLReader gmlReader = new GMLReader();
gmlReader.acceptSRID(true);
gmlReader.processMultiItems(true);
try {
fc = gmlReader.read(dp);
} catch (Exception e) {
e.printStackTrace();
}
You may also replace the original jar file in your OpenJump 1.9.1 lib folder with this one and use OpenJump GUI and input xml templates to load OSMM GML files.