2.7.2. Rules for using internal polygons
Both simple and composite polygonal items can have internal polygons. These are polygons that are entirely located within the borders of another "mother" polygon and are considered to be part of that bigger polygon, rather than separate items.
They are only used if the mother item contains parts that represent a different geological or other phenomenon, both parts belong to the same category (and there is no specific type of item from that category that the lesser part could belong to).
- For example, you should use an internal polygon if you need to draw a courtyard (courtyards are part of the Building item category; there is no separate Courtyard item type on Yandex Map Editor). You would also use an internal polygon if you need to draw a clearing in the woods (clearings belong to the Woodlands category, but there is no Clearing item type on YME).
If you need to draw an item within the mother polygon that belongs to another category (i.e. not the category of the external polygon), then you should not use an internal polygon.
- For example, a reservoir in the woods should not be drawn as a separate Reservoir polygonal item. Otherwise you will have to draw the reservoir twice: as an internal polygon of a woodlands item and as a Reservoir hydrographic item. When this happens, the borders of the two polygons that represent the same item inevitably don't match, so it doesn't display correctly on the map.
The exception to this rule is for Island and Archipelago items. If islands (archipelagos) are located within hydrographic items of the
Ocean, sea, bay, or strait category,
they are drawn as internal polygons.
If the island or archipelago is located within a Lake, water basin, pond, swamp, glacier, outdoor pool, or lake, however,
then it is not drawn as internal polygon.
Examples of situations when you shouldn't use internal polygons:
- 188.8.131.52. Example 1. When to use internal polygons
- 184.108.40.206. Example 2. When not to use internal polygons
- 220.127.116.11. Example 3. When to use a combination of internal polygons and regular polygons
18.104.22.168. Example 1. When to use internal polygons
Internal polygons should be used when drawing:
Courtyards in buildings (there is no Courtyard item on Yandex Map Editor):
Clearings or paths in the woods (there are no Clearing or Path items on YME):
Islands located within the borders of hydrographic items that belong to the ocean, sea, bay, or strait categories (this is despite the fact that there is an Island type within the Terrain category).
If an archipelago is located within the borders of two different hydrography items, then you must create internal polygons for it within both of those items.
22.214.171.124. Example 2. When not to use internal polygons
Internal polygons should not be used when drawing the following:
Outlines of reservoirs located within woodlands items (there is a Reservoir item under the Hydrography category on YME):
Outlines of woodlands located within island items (there is an Islands item under the Terrain category and a Woodlands item under the Vegetation category on YME):
Islands located within the borders of hydrographic items that belong to the lake, reservoir, water basin, pond, swamp, glacier, outdoor pool, and lake group categories (on Yandex Map Editor there is an Island item within the Terrain category):
Terrain items located on islands. For example, a volcano on an island can be drawn as a separate terrain item, but it should not be drawn as an internal polygon within an island item.
126.96.36.199. Example 3. When to use a combination of internal polygons and regular polygons
If you need to draw an item like a reservoir within a woodlands area (i.e. you have a situation where you can't use an internal polygon), but it is located within a clearing (i.e. you should use an internal polygon), then draw the item using a combination of an internal polygon and a regular polygon.
Clearings in woods are drawn as internal polygons within woodlands (the green dotted line in the drawing), but reservoirs within clearings are drawn as separate polygons (highlighted in the drawing):