Vicmap Property - Property Polygon associated Display View Polygon Table

Part of VMPROP, PROPERTY_VIEW_DVP is an Aspatial table. It is created by comparing the polygons in the PROPERTY_VIEW table with the polygons in the DISPLAY_VIEW_POLYGON table. It holds a record for each PFI in the PROPERTY_VIEW table, and the DISPLAY column has a value indicating whether the polygon is Inside, Outside, or Both (partly inside and partly outside) a DISPLAY_VIEW_POLYGON polygon.This table provides a way of limiting the display of property_view polygons so maps can be drawn efficiently. Polygons with a DISPLAY value of I (inside) can be drawn at larger scales (eg 1:5000), while those with O (outside) can be drawn at smaller scales (eg. 1:50,000). This means rural areas can be displayed at a suitable scale, without the burden of displaying polygons in a town. A DISPLAY value of B (both) is used for some polygons, which can be drawn at both scales. These can be rivers, or multi-part polygons with parts inside and outside the DVP. To use this flag for drawing a join is needed - property_view.pfi = property_view_dvp.property_view_pfi

PROPERTY_VIEW_DVP 作为 VMPROP 的组成部分，属于非空间表（Aspatial table）。该表通过比对 PROPERTY_VIEW 表与 DISPLAY_VIEW_POLYGON 表中的多边形要素生成，为 PROPERTY_VIEW 表中的每一项 PFI 生成一条独立记录。其 DISPLAY 字段用于标识对应多边形处于 DISPLAY_VIEW_POLYGON 多边形的内部（Inside）、外部（Outside）还是双向（Both，即部分位于内部、部分位于外部）。该表可用于限制 property_view 多边形的显示范围，以实现地图的高效绘制：DISPLAY 字段取值为 I（内部）的多边形可在更大比例尺下绘制（例如1:5000），取值为 O（外部）的多边形则可在较小比例尺下绘制（例如1:50000）。此举可使乡村区域以适配比例尺展示，无需承担城镇区域多边形显示的额外负担。部分多边形的 DISPLAY 字段取值为 B（双向），这类多边形可在两种比例尺下绘制，通常为河流，或是存在部分位于DVP内部、部分位于外部的多部分多边形。若要在绘制流程中使用该标识，需建立关联连接：property_view.pfi = property_view_dvp.property_view_pfi。