private void assignVertexIds() {
   pointLocator = new PointLocator();
   for (Acre acre : sector.getInnerAcres()) {
     Point[] midpoints = AcreSeamSeq.buildMidpoints(acre);
     acre.seamStartVertexIds = buildSeamStarts(acre.packId, midpoints);
     acre.zoneStartVertexIds = buildZoneStarts(acre.packId, acre.points.length);
     acre.topographyDef = buildTopographyDef(acre.center, acre.points);
   }
   for (Acre acre : sector.getSharedAcres()) {
     Point[] midpoints = AcreSeamSeq.buildMidpoints(acre);
     acre.seamStartVertexIds = buildSeamStarts(acre.packId, midpoints);
     acre.zoneStartVertexIds = buildZoneStarts(acre.packId, acre.points.length);
     acre.topographyDef = buildTopographyDef(acre.center, acre.points);
   }
 }