Add an how-to guide for the map view

docs/content/howto/visualization/geospatial-data.md

@@ -0,0 +1,51 @@
+---
+title: Visualize geospatial data
+order: 300
+---
+
+Rerun 0.20 introduced a new, experimental [map view](../../reference/types/views/map_view.md).
+This guide provides a short overview on how to use it to visualise geospatial data.
+
+## Coordinate system
+
+The map view uses the [ESPG:3857](https://epsg.io/3857) [spherical mercator projection](https://en.wikipedia.org/wiki/Web_Mercator_projection) commonly used by web services such as [OpenStreetMap](https://www.openstreetmap.org/).
+This enables the use of commonly available web tiles for the background map.
+
+To be compatible with this view, geospatial data must be expressed using [ESPG:4326](https://epsg.io/4326) (aka WGS84) latitudes and longitudes.
+This corresponds to what is commonly referred to as "GPS coordinates."
+Rerun provides a set of archetypes prefixed with `Geo` designed to encapsulate such data.
+
+For example, [`GeoPoints`](../../reference/types/archetypes/geo_points.md) represent a single geospatial location (or a batch thereof). The location of the Eiffel Tower can be logged as follows:
+
+```python
+rr.log("eiffel_tower", rr.GeoPoints(lat_lon=[48.858222, 2.2945]))
+```
+
+Both the latitude and longitude must be provided in degrees, with positive values corresponding to the North, resp. East directions.
+
+Note that Rerun always expects latitudes first and longitudes second.
+As there is [no accepted ordering standard](https://stackoverflow.com/questions/7309121/preferred-order-of-writing-latitude-longitude-tuples-in-gis-services), our APIs strive to make this ordering choice as explicit as possible.
+In this case, the `lat_lon` argument is keyword-only and must thus be explicitly named as a reminder of this order.
+
+
+## Types of geometries
+
+Rerun currently supports two types of geometries:
+
+- [`GeoPoints`](../../reference/types/archetypes/geo_points.md): batch of individual points, with optional [radius](../../reference/types/components/radius.md) and [color](../../reference/types/components/color.md)
+- [`GeoLineStrings`](../../reference/types/archetypes/geo_line_strings.md): batch of line strings, with optional [radius](../../reference/types/components/radius.md) and [color](../../reference/types/components/color.md)
+
+*Note*: polygons are planned but are not supported yet (see [this issue](https://github.com/rerun-io/rerun/issues/8066)).
+
+As in other views, radii may be expressed either as UI points (negative values) or scene units (positive values).
+For the latter case, the map view uses meters are scene units.
+
+Apart from the use of latitude and longitude, `GeoPoints` and `GeoLineStrings` are otherwise similar to the [`Points2D`](../../reference/types/archetypes/points2d.md) and [`LineStrip2D`](../../reference/types/archetypes/line_strips2d.md) archetypes used in the [2D view](../../reference/types/views/spatial2d_view.md).
+
+
+## Using Mapbox background maps <!-- NOLINT -->
+
+The map view supports several types of background maps, including a few from [Mapbox](https://www.mapbox.com).
+A Mapbox access token is required to use them.
+It must be provided either using the `RERUN_MAPBOX_ACCESS_TOKEN` environment variable or configured in the settings screen ("Settings…" item in the Rerun menu).
+An access token may be freely obtained by creating a Mapbox account.