title: $:/plugins/tiddlywiki/geospatial/docs

! Macros

!! `show-geojson` macro

The `show-geojson` operator displays a GeoJSON object in a human-readable form.

|!Parameter |!Description |
|geojson |Text of GeoJSON object to display |

```
<$macrocall $name="show-geojson" geojson={{$:/geospatialdemo/features/us-states}}/>
```

! Filter Operators

!! `geopoint` operator

The `geopoint` operator converts separate latitude, longitude and (optionally) altitude numbers into a [[GeoJSON Point Feature]] that can be used with other geospatial primitives.

The coordinates are specified as two or three operands:

```
[geopoint<latitude>,<longitude>,<attitude>]
```

Any operands that cannot be interpreted as a valid number will be interpreted as the value zero.

For example:

```
<$text text={{{ [geopoint[51.751944],[-1.257778]] }}}/>
```

Returns:

```
{"type":"Feature","properties":{},"geometry":{"type":"Point","coordinates":[51.751944,-1.257778,0]}}
```

!! `geodistance` operator



!! `geounion` operator

The `geounion` operator calculates the union between two or more [[GeoJSON Polygon Features|GeoJSON Polygon Feature]].

Each input list item is interpreted as a [[GeoJSON Polygon Feature Collection]] containing polygons. Any item that 

```
[geounion[]]
```
etc for geointersect and geodifference

!! `geolookup` operator

!! `olc-decode` operator

The `olc-decode` operator converts an [[OpenLocationCode|https://github.com/google/open-location-code]] shortcut into the [[GeoJSON Point Feature]] at its centre or the [[GeoJSON Polygon Feature]] representing the bounds of the area identified by the input code.

```
[olc-decode:bounds[9C3WQP2R+QV]]
[olc-decode:point[9C3WQP2R+QVH]]
```

!! `olc-encode` operator

The `old-encode` operator converts separate latitude, longitude and (optionally) altitude numbers into an [[OpenLocationCode|https://github.com/google/open-location-code]] shortcut code with a specified length.

```
[olc-encode[51.751944],[-1.257778]]
[olc-encode[51.751944],[-1.257778],[11]]
```