Lines
Draw lines on the map between two sets of longitude and latitude coordinates.
Data Setup
In order to display lines the following fields should be configured:
- ID - a unique ID representing a line
- Longitude - The longitude of the coordinate at the line start
- Latitude - The latitude of the coordinate at the line start
- Destination Longitude - The longitude of the coordinate at the line destination
- Destination Latitude - The latitude of the coordinate at the line destination
It is then necessary to enable the Lines toggle in the "Data Layers" section of the formatting options of the map.
Sample data
| ID | Longitude | Latitude | Destination Longitude | Destination Latitude | Circle Size | Cluster Group | H3 Weight | Heatmap Weight | Image / WKT / GeoJSON | Feature Reference | Feature Weight |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Line1 | -2.576 | 51.481 | 0.153 | 52.187 | null | null | null | null | null | null | null |
| Line2 | -2.576 | 51.481 | -0.180 | 52.331 | null | null | null | null | null | null | null |
When configured, it is possible to draw a circle at the start and/or end of a line. In which case the circle size should also be specified:
| ID | Longitude | Latitude | Destination Longitude | Destination Latitude | Circle Size | Cluster Group | H3 Weight | Heatmap Weight | Image / WKT / GeoJSON | Feature Reference | Feature Weight |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Line1 | -2.576 | 51.481 | 0.153 | 52.187 | 10 | null | null | null | null | null | null |
| Line2 | -2.576 | 51.481 | -0.180 | 52.331 | 20 | null | null | null | null | null | null |
Configuration
There are a number of configuration options available for lines:
Include in Auto Zoom
Whether the start and end of the line should be included in the auto zoom of the map. Can be set to yes or no using conditional formatting to apply to specific lines.
Include Tooltip
Whether to include a tooltip. Can be set to yes or no using conditional formatting to apply to specific lines.
Selectable
Whether the line can be clicked on for interaction with other visuals. Can be set to yes or no using conditional formatting to apply to specific lines.
Include circle(s) at
Enables circles to be drawn at the start, end or both ends of a line. Or neither. When enabled, the circle size should be specified using the "Circle Size" data field. The Circles data layer type also needs to be enabled.
An example file is available showing this approach.
Image at start of the line
It is possible to display an image the start of the line, without having to add it as an image with a separate row in your Power BI dataset.
Image URL at start
Specify an image to display at the line start. This can be hardcoded so that all lines display the same image, or use a DAX expression or field value for different images at each line start. URLs should start https or data. The same rules should be followed as other map images.
Image Width and Height
These settings allow you to set the size of the image and represent the width and height in pixels. This can be hardcoded, or set using conditional formatting from a DAX measure or field value.
Rotation
This should represent a number between 0 and 359 and represents the number of degrees to rotate the image. This can be hardcoded, or set using conditional formatting from a DAX measure or field value.
Transparency
Represents the percentage transparency of the image and should be a numeric value between 0 and 100. This can be hardcoded, or set using conditional formatting from a DAX measure or field value.
Image at end of the line
It is possible to display an image the end of the line, without having to add it as an image with a separate row in your Power BI dataset.
Image URL at end
Specify an image to display at the line end. This can be hardcoded so that all lines display the same image, or use a DAX expression or field value for different images at each line destination. URLs should start https or data. The same rules should be followed as other map images.
Image Width and Height
These settings allow you to set the size of the image and represent the width and height in pixels. This can be hardcoded, or set using conditional formatting from a DAX measure or field value.
Rotation
This should represent a number between 0 and 359 and represents the number of degrees to rotate the image. This can be hardcoded, or set using conditional formatting from a DAX measure or field value.
Transparency
Represents the percentage transparency of the image and should be a numeric value between 0 and 100. This can be hardcoded, or set using conditional formatting from a DAX measure or field value.
Z Index
Determines the order in which layers are displayed. The higher the number, the nearer the foreground.
EPSG (Coordinate Reference System)
Allows you to specify a specific reference system for your coordinates. The default used is EPSG:4326 / WGS84 and expects longitude and latitude coordinates. You can use other coordinate systems by specifying the relevant EPSG number. For example, to use British National Grid coordinates, enter 27700. Other EPSG codes can be found here.
Maximum and Minimum Zoom
The zoom levels between which the layer should be displayed.
Formatting
All line formatting options can be set to apply to all lines, or use conditional formatting to apply values to specific lines.
Color
Color to draw the line
Color Type
Determines whether the color should be a single color or a gradient.
When gradient colors are enabled, it is not possible to set the colors of the lines using conditional formatting.
Only available when WebGL rendering is enabled.
Transparency
A number between 0 and 100.
Width
The line width in pixels. This can be a decimal number to achieve thinner lines.
Line Shape
Lines can be one of the following options:
- Straight - draws a line that appears straight on the map directly between the two points.
- Curved - draws a line that appears curved between the two points. Only available in standard rendering mode.
- Shortest - draws a line that follows the curvature of the earth.
- Flow - groups lines by their origin and draws curved paths between source and destination points. Line thickness and color are based on the flow weight, making it easy to visualize the relative volume of movement between locations. Only available when WebGL rendering is enabled.
- Smoothed Flow - similar to Flow, but applies edge smoothing to produce visually cleaner branching where multiple flows share a common origin. This creates a more polished, tree-like appearance. Only available when WebGL rendering is enabled.
- Flow arcs - draws each row as its own independent curved arc between origin and destination: the classic origin-destination flow map. Arcs bow to the right of their direction of travel, so flows in opposite directions between the same two points automatically curve to opposite sides and never overlap. Line thickness scales with the flow weight, arcs stop a fixed number of screen pixels short of their end points at every zoom level, and each arc can carry an outlined arrowhead and a value label. Only available when WebGL rendering is enabled.
When Flow, Smoothed Flow or Flow arcs is selected, the following additional formatting options become available:
Weight for Flow
A numeric value that determines the weight/volume of each flow line. This affects the line thickness and color interpolation. Can be set using conditional formatting.
Gradient Color 1 and Gradient Color 2
Flow and Smoothed Flow lines are always rendered using a two-color gradient based on weight. Lighter-weight flows use Gradient Color 1 and heavier flows transition towards Gradient Color 2. Flow arcs can use either a single solid Color or the weight gradient, chosen with the Color Type option.
Min Width and Max Width
Control the range of line widths. Lighter flows are drawn at the minimum width and heavier flows at the maximum width.
Data Label At Destination
When enabled, displays a data label at the destination point of each flow line. Requires Data Labels to be configured. Flow and Smoothed Flow only - Flow arcs use the Label Position option below instead.
When Flow arcs is selected, these additional options are also available:
Arc Curvature (%)
How strongly each arc bows, as a percentage of the distance between its origin and destination. 0 draws straight lines; the default of 18 gives the classic gently-curved flow-map look.
Trim at Origin (px) and Trim at Destination (px)
Stops each arc the given number of screen pixels short of its end points, so flows never pile up on the locations they connect. Trim at Destination is measured to the tip of the arrowhead (when arrowheads are on), so the value is simply the gap you want between the arrow and the destination marker - for example a Trim at Destination of 12 with 8 pixel circles leaves a 4 pixel gap. The gaps are screen-space: they stay the same size as you zoom in and out, matching pixel-sized markers drawn at the locations.
Arrowheads and Arrowhead Size
Draws a triangular arrowhead at the destination end of each arc, continuing the line into the end gap and pointing at the destination. Arrowheads scale with each arc's width - the heaviest flow gets the largest arrowhead. Arrowhead Size sets the size on the widest arc.
Outline Color and Outline Width
Draws a contrasting outline around both the arcs and their arrowheads - the classic flow-map casing that makes the flows pop against the basemap. Set the width to 0 to turn the outline off.
Label Position
Where each flow's data label is placed: None, Arc Midpoint (a value label riding the middle of the arc - configure the text with the Data Labels' Label Text conditional formatting, for example a percentage measure), or Destination.
Outline Blur
How much the line should be blurred.
Only available when WebGL rendering is enabled.
Invisible Line Width
Creates an invisible line as well as the visible line when the width is greater than the visible width. A larger invisible width can help when clicking or hovering over narrow lines.
Only available when WebGL rendering is enabled.
Dash Array
The dash array determines the pattern used for the line. It consists of a series of space separated numbers. Each value represents the length along the line that should be painted (the dash) and then not painted (the gap). Eg:
4 4
Please note this capability is not available when WebGL rendering is enabled.
Dash Animation Speed
If a dash array is used to draw a line pattern, it can be animated to show the direction of travel. The speed can be a negative or positive number, such as 10.
Please note this capability is not available when WebGL rendering is enabled.
Line Symbols
It is possible to add a symbol along the path of a line. This feature is not available for "Curved" lines, but is available for "Straight" and "Shortest".
Include Line Symbol
Determines whether symbols are displayed. Can be set using conditional formatting values "yes" or "no" to determine the setting for each individual line.
Line Symbol Text
The text/symbol that is drawn along the line. Use Unicode Characters to draw symbols such as planes, arrows etc. Symbols should face towards the right to show in the direction of the line. Use spaces to determine the gaps between. This setting can be determined using conditional formatting to show different text or a different symbol for each line.
Line Symbol Color
Set the color of the symbol or text.
Line Symbol Size
Set the size of the symbol/text in pixels
Line Symbol Orientation
This determines how the symbols are drawn:
- Normal - oriented along the direction of the line
- Flipped - rotated by 180 degrees
- Perpendicular - rotated by 90 degrees
Line Symbol Offset
Ensure your symbols are aligned to the center of the line, or offset below or above. This value can be a negative number to draw text above the line.
Please note this capability is not available when WebGL rendering is enabled.
Line Symbol Repeat
Determines whether one symbol is shown, or multiple. Can be set using conditional formatting using the values "yes" or "no".
Symbol Halo Color
The outline color for symbol text
Only available when WebGL rendering is enabled.
Symbol Halo Width
The width of the halo
Only available when WebGL rendering is enabled.
Symbol Halo Blur
How much the halo should be blurred.
Only available when WebGL rendering is enabled.