Lines

The Lines layer draws a connection from an origin to a destination for every row of your data. Use it for flights, shipments, journeys, migration, network links and any other movement between two places.

What you need

Each row is one line. Add these fields to the visual:

The four coordinate field wells take one numeric field each. Power BI summarizes them for each ID, so choose a summarization that returns the coordinate itself, such as Average.

Optional fields:

• Tooltips - the values shown when you point at a line.
• Circle Size - only if you want a circle at the ends of each line (see Circles at the ends).

These fields must be empty on a line's row, otherwise the row belongs to another layer and no line is drawn: Feature Reference, Image / WKT / GeoJSON, Heatmap Weight and Cell (H3/S2/A5/Geohash) Weight. See Combine several layers in one map.

Add a lines layer

1. Add the five fields above to the visual.
2. If the panel What kind of map are you making? is showing, select the Lines & flows tile. Otherwise, in the Format pane expand Data Layers and, in the Data Layers group, turn on Lines.
3. In the Lines - Formatting group, choose a Line Shape.
4. Set Color and Width, or the weight and width range for a flow shape.

New in 1.0.1.2 You can also add the layer in the Layer Manager: in the Format pane, expand Layer Manager, switch on Open Layer Manager and add a Lines & flows data layer. Selecting the tile in What kind of map are you making? turns the layer on and opens its editor in the Layer Manager. Conditional formatting stays in the Format pane. See Add a layer.

Line shapes

Format pane > Data Layers > Lines - Formatting > Line Shape decides how each line is drawn and which of the other settings apply. The list is always in this order:

Line Shape is one choice for the whole layer.

Straight / Rhumb

A straight line on the flat map between the origin and the destination: a line of constant compass direction, called a rhumb line. A line that crosses the 180 degree meridian is split into two parts.

Every row is its own line, so rows that share the same two points draw on top of each other. Straight lines support everything in the Lines card: per-row color and width, a gradient, dashes and dash animation, blur, line symbols, and images or circles at the ends.

Shortest

The great-circle path between the two points, as a flight would take. On a flat map the line curves toward the poles. On the globe it is the direct path. The line is drawn in one piece, including across the 180 degree meridian.

Shortest supports the same options as Straight / Rhumb. A row whose origin and destination are the same point draws nothing.

3D Arcs

Each row is an arc that follows the great-circle path and rises off the ground, highest in the middle. Longer arcs rise higher. From straight above, an arc looks like a Shortest line, so tilt the map to see the height. See View, zoom and projection for tilt.

Settings that apply only to 3D Arcs:

• Amplitude - how high the arcs rise. 10 is the default, 1 is almost flat, 50 is five times the default height. Accepts conditional formatting.
• Glow - a soft halo around each arc.
• Fade From Origin - each arc starts faint at the origin and reaches full strength at the destination, so the direction is clear.
• Taper From Origin - each arc starts narrow and widens to its destination.
• Comet Speed - a bright head with a fading tail travels along each arc from origin to destination. 0 turns the comets off. At speed 1 a trip takes 12.5 seconds, at speed 10 it takes 1.25 seconds.

With Color Type set to Gradient, every arc runs from Gradient Color 1 at the origin to Gradient Color 2 at the destination. 3D Arcs do not have dashes, blur or line symbols. Images and circles at the ends are still drawn. On the globe, the parts of an arc behind the Earth are hidden.

Flow arcs

One flat, curved arrow for each row. Nothing is merged, so every origin and destination pair is visible on its own. Arcs bow to the right of the direction of travel, so a flow from A to B and a flow from B to A separate into two arrows.

• Weight for Flow sets each arc's width, between Min Width and Max Width across all rows of the layer.
• Arc Curvature (%) is the height of the bow as a percentage of the distance between the two points.
• With Color Type set to Solid, each row takes its own Color. With Gradient, each arc is one flat color picked by its weight between Gradient Color 1 (a weight of 1 or less) and Gradient Color 2 (100 or more).
• Trim at Origin (px) and Trim at Destination (px) stop each arc short of its ends, by the same number of screen pixels at every zoom level. Use them to keep arrows clear of circles or icons at the ends.
• Arrowheads and Arrowhead Size control the head. The size applies to the widest arc and thinner arcs scale down.
• Taper From Origin starts each arc narrow and widens it toward the head.
• Outline Color and Outline Width draw a contrasting outline around the arc and its arrowhead.
• Label Position places the data label: None, Arc Midpoint or Destination.

Flow Tree

One tree for each origin, drawn as ribbons. Destinations are grouped by direction. Every branch is a smooth curve whose width follows its flow, and where a branch splits, the smaller ribbons leave side by side and fill the width of the parent.

• Weight for Flow sets each row's flow. A branch carries the sum of the rows beneath it.
• The heaviest trunk on the map is Max Width and nothing is narrower than Min Width.
• Grouping decides how eagerly flows are joined: Bundled joins the most flows into shared trunks. Balanced keeps the trunks but lets branches leave earlier, so fewer double back. Fewest Crossings only joins flows next to each other in direction, which is the tidiest but bundles the least.
• A tree has one color. Every ribbon takes the Color of the first row of its origin, so use a conditional formatting rule that gives every row of an origin the same color.
• Trim at Origin (px), Trim at Destination (px), Taper From Origin, Arrowheads, Arrowhead Size, Outline Color and Outline Width work as they do for Flow arcs. The outline runs around the outside of each tree.
• Label Position is None, Midpoint or Destination. Midpoint places each destination's label halfway along its own final branch.
• Rows only share a tree when their origin coordinates are exactly the same.

Pointing at a destination's ribbon shows that row's tooltip. Pointing at a shared branch shows the same tooltip fields summarized over every row beneath it. Clicking a destination's ribbon selects its row, and clicking a shared branch selects every row beneath it.

Routes

Lines that share a street are drawn side by side, each in its own color, as on a bus or metro map. Routes has its own page: Routes.

Dashes and animation

For Straight / Rhumb and Shortest lines with Color Type set to Solid:

• Dash Array is a list of numbers separated by spaces or commas, read as dash, gap, dash, gap, in multiples of the line width. For example 2 4 draws a dash two widths long followed by a gap four widths long. It needs at least two numbers. Use conditional formatting to give different lines different patterns.
• Dash Animation Speed makes the dashes travel along the line. 0 is still. A negative value reverses the direction. The speed applies to the whole layer.

Dashes cannot be combined with a gradient. When Color Type is Gradient, the dash settings are replaced by a note.

Line symbols

For Straight / Rhumb and Shortest lines you can draw text or a character along each line, for example an arrow that shows direction. Set Include Line Symbol (Straight / Shortest only) to Yes, then choose the Line Symbol Text, color and size.

• Line Symbol Repeat - Yes repeats the symbol at intervals along the line. The spacing depends on the zoom: at country scale a line may carry one symbol or none, and more appear as you zoom in. No draws it once at the center.
• Line Symbol Orientation - With Line Direction makes the text follow the line from origin to destination, so a plain arrow character such as > points at the destination. Keep Upright flips text where needed so it is never upside down.
• Symbol Halo Color, Symbol Halo Width and Symbol Halo Blur add an outline around the symbol.

Images at the ends

Image at start and Image at end place an image at the origin or destination of each line, for example a plane or a ship. They are drawn for Straight / Rhumb, Shortest and 3D Arcs.

Each takes a data URI (data:image/...) or SVG text, and accepts conditional formatting, so the image can come from your data. A link to an image is not drawn, because Icon Map Lite downloads nothing. See Images and icons for how to put images in your data.

Each image has its own Image Height, Image Width, Image Rotation and Transparency. The rotation is fixed. It does not follow the direction of the line.

Circles at the ends

Include circle(s) at: draws a circle at the Start, the End or Both ends of each line. The circles are drawn by the Circles layer, so:

• Turn on the Circles layer. Until you do, the pane shows "Circle layer must be enabled for circle(s) to be displayed."
• Add a field to Circle Size.

The circles take the Circles layer's formatting, tooltips and zoom range. This works with every line shape.

Selection, tooltips and labels

• Selection - click a Straight / Rhumb, Shortest or 3D Arcs line to select its row and filter the other visuals on the report page. Hold Ctrl or Shift to add to the selection. On a Flow Tree, a destination's ribbon selects its row and a shared branch selects every row beneath it. On Routes, a click selects the whole route. Set Selectable to No to turn this off. See Select and filter with the map.
• Tooltips - pointing at a Straight / Rhumb, Shortest, 3D Arcs, Flow Tree or Routes line shows the fields in Tooltips. Set Include Tooltip to No to turn them off. See Tooltips.
• Labels - Straight / Rhumb, Shortest and 3D Arcs lines carry their data label at the midpoint. Flow arcs and Flow Tree use Label Position. See Data labels.
• Auto zoom - rows with Include in Auto Zoom set to Yes are included when the map zooms to fit your data.

Settings

All settings are in Format pane > Data Layers. The fx column shows which settings accept conditional formatting.

Lines - Configuration

The image settings are not shown for Flow Tree and Routes.

Lines - Formatting: shape, color and width

Lines - Formatting: flow arcs and flow trees

Lines - Formatting: 3D arcs

Lines - Formatting: dashes and symbols

These are shown for Straight / Rhumb and Shortest.

The Routes settings (Route Name, Merge Distance (m), Route Outline Color, Route Outline Width, Route Badges) are described on the Routes page.

Coordinate systems

By default the coordinates are longitude and latitude in decimal degrees (EPSG 4326). If your data uses a projected coordinate system, such as British National Grid, enter its EPSG number in EPSG, for example 27700. Enter the number only. Put the X value in Longitude (X) and Destination Longitude, and the Y value in Latitude (Y) and Destination Latitude.

EPSG applies to every line shape.

Circles at the ends of lines use the Circles layer's own EPSG setting.

Tips and limits

• A map has one Lines layer. Every line row is drawn by it.
• A row needs all four coordinates. A row with a blank coordinate is skipped.
• Minimum Zoom and Maximum Zoom apply to Straight / Rhumb, Shortest, Flow Tree and Routes lines.
• Destination Latitude and Destination Longitude are easy to swap. If no lines appear, check that the latitudes are between -90 and 90.
• Thin lines are easier to click than they look: each Straight / Rhumb and Shortest line has a slightly wider, invisible area that takes clicks and tooltips.
• The visual receives 30,000 rows by default. See Data rows and limits.
• To show lines and other layers together, for example stores as circles and deliveries as lines, see Combine several layers in one map.

Related

• Routes
• Circles
• Combine several layers in one map
• Conditional formatting
• Data labels
• Legend