Using callout lines with labels

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Callouts of type line can be set on labels or on the symbol. A callout can only be set either on the label or on the symbol, but not on both.

labels-callout

Setting callouts on labels can be helpful to connect the label with its corresponding symbol. In this way, the user can clearly identify for each label to which feature it belongs.

For setting callouts on the symbols check the Point styles for cities sample.

In this sample we want to show the highest mountain peaks of Switzerland, Europe. The peaks are symbolized with black circles and labels are connected to the symbols with callout lines. The labels have a transparent halo for better readability and a custom font:

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const symbol = {
  type: "label-3d", // autocasts as new LabelSymbol3D()
  symbolLayers: [
    {
      type: "text", // autocasts as new TextSymbol3DLayer()
      material: {
        color: "black"
      },
      halo: {
        color: [255, 255, 255, 0.7],
        size: 2
      },
      font: {
        family: "Crimson Pro",
        weight: "bold"
      },
      size: 10
    }
  ],
  verticalOffset: {
    screenLength: 150,
    maxWorldLength: 2000,
    minWorldLength: 30
  },
  callout: {
    type: "line", // autocasts as new LineCallout3D()
    size: 0.5,
    color: [0, 0, 0],
    border: {
      color: [255, 255, 255]
    }
  }
};

This sample also uses screenSizePerspective to give a better perception of depth. See the Labeling guide page for more information and known limitations.