Temporal cursor

Move the pointer along a Time series graph and an amber marker follows the vehicle on the map, at the position it had at that instant. Move it along the track or the map's time bar and the graphs' crosshair follows instead. This is the shared cursor Grafana already passes between graphs, with the map taking part in it.

Nothing is queried while hovering. The track is already in the browser: each move is a binary search through its samples and a redraw of one marker, so it stays fluid with a hundred thousand points.

Setting it up

1. In the dashboard settings, set Graph tooltip to Shared crosshair or Shared tooltip. Without that, graphs do not publish their cursor at all.
2. In the map panel, turn on Temporal cursor → Show position on graph hover.
3. For the other direction too, turn on Map hover drives graphs.

Both are off by default. With the first one off, the panel, including its time bar, behaves exactly as before.

Option	Default	What it does
Show position on graph hover	off	Draws the marker for a graph's cursor, and the cursor's line on the time bar.
Map hover drives graphs	off	Hovering a Point sample or the time bar moves the graphs' cursor.
Layer	all compatible, visible	Restricts the marker to one saved layer.
Maximum sample age (seconds)	60	Hides the marker when the last sample before the cursor is older than this.

Which layers

Layer	Marker
Point	Yes, with a mapped time, latitude and longitude.
Trip, table	Yes. The trip ID separates vehicles.
Trip, timestamped GeoJSON	Yes: a LineString with [longitude, latitude, altitude, timestamp].
Heatmap, Hexagon, Grid, Cluster	No: they draw aggregates, not a position.
Raster, WMS, Esri, Zarr	No: they have their own timelines.

A Point dataset without a trip ID is treated as one track. Map a trip ID to follow several vehicles: each gets its own marker.

To follow one layer only, Save current map configuration first, so its id exists, and then choose it under Temporal cursor → Layer. Hidden layers, and layers hidden on one side of a split map, get no marker on that side. The map's filters apply to the marker too: a sample filtered out has none.

What the marker shows

The last sample at or before the cursor. It is never extended past a track's first or last timestamp, and it disappears where the gap to the previous sample is larger than Maximum sample age — raise it for GPS that reports every few minutes. There is no interpolation between samples yet.

From the map to the graphs

With Map hover drives graphs on, hovering a sample of a Point layer publishes that sample's time, so every graph's crosshair and every other map's marker moves to it. Trip layers do not publish yet: kepler identifies a hovered trip as the whole path, not the vertex under the pointer.

The time bar

The map's time bar takes part in both directions, in its minified and enlarged forms. A graph's cursor is drawn on it as an amber line. With Map hover drives graphs on, hovering the bar publishes the time under the pointer. Dragging a handle publishes nothing: the pointer is moving the brush, not asking about a time.

The minified bar sits between two dates, so in a narrow panel it has little room to hover. The enlarged one spans the widget and draws the data under it, which makes it the easier one to hover.

What it does not do

• It does not change the dashboard range, write variables, move the trip animation or re-run a query. It works alongside every time range sync mode and peer time sync.
• Grafana's Stat, Gauge and Bar gauge panels do not listen to the shared cursor: they always reduce the whole range. A Time series with Tooltip → All shows every series at the cursor instead.

Example: GPS truck track

The GPS truck track dashboard, provisioned on the development benches, puts all of it together on one 30-minute trip:

• a real road from Hamburg to Reading, Pennsylvania (© OpenStreetMap contributors, ODbL, routed by OSRM), with synthetic speed and elevation;
• a 3D view of the track coloured by speed, and an enlarged time bar plotting the mean speed per minute;
• the map and the stats following the dashboard range;
• the map's time brush shaded on both graphs, with time window variables.

It is built by testdata/make-gps-truck.py, which writes a TestData copy for the :3000 bench and an Infinity copy for :3002.