private URI createNorthArrowSubReport(final File printDirectory,
final Dimension size,
final List<URI> graphics,
final double dpi) throws IOException, JRException {
final MapSubReport subReport = new MapSubReport(graphics, size, dpi);
final File compiledReport = File.createTempFile("north-arrow-report-",
JasperReportBuilder.JASPER_REPORT_COMPILED_FILE_EXT, printDirectory);
subReport.compile(compiledReport);
return compiledReport.toURI();
}