Verify the TerraDraw instance

Oct 13, 2025 by magicalceylontours.com 118 views

BUG: Issue Rendering Custom GeoJSON Polygon with TerraDraw's addFeatures Method

Introduction

TerraDraw is a powerful tool for creating and editing geospatial data on a map. However, users have reported issues with rendering custom GeoJSON polygons using the addFeatures method. In this article, we will explore the issue and provide guidance on how to successfully load custom polygons.

Select Items Related to this Issue

maplibre-gl-terradraw

Bug Description

The issue arises when attempting to load a custom GeoJSON polygon using the addFeatures method in TerraDraw. Despite following the example provided by TerraDraw, users are unable to render their custom polygon.

Bug Reproduction

To replicate the problem, we will use the following code:

<!doctype html>
<html lang="en">
<head>
  <title>Adding default GeoJSON feature to TerraDraw</title>
		<meta
			property="og:description"
			content="You can add GeoJSON features by using addFeatures() function in the TerraDraw instance which can be retrieved through getTerraDrawInstance() function."
		/>
  <meta charset="utf-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  <link rel="stylesheet" href="https://unpkg.com/maplibre-gl/dist/maplibre-gl.css" />
  <script src="https://unpkg.com/maplibre-gl/dist/maplibre-gl.js"></script>
  <style>
    body {
      margin: 0;
      padding: 0;
    }
    html,
    body,
    #map {
      height: 100%;
    }
  </style>
</head>
<body>
		<script src="https://cdn.jsdelivr.net/npm/@watergis/maplibre-gl-terradraw@1.3.2/dist/maplibre-gl-terradraw.umd.js"></script>
		<link
			rel="stylesheet"
			href="https://cdn.jsdelivr.net/npm/@watergis/maplibre-gl-terradraw@1.3.2/dist/maplibre-gl-terradraw.css"
		/>
  <div id="map"></div>

  <script>
    const map = new maplibregl.Map({
      container: 'map',
      style: 'https://demotiles.maplibre.org/style.json',
      center: [0, 0],
      zoom: 1,
      maxPitch: 85
    });

    const drawControl = new MaplibreTerradrawControl.MaplibreTerradrawControl({
      modes: ['polygon', 'select'],
      open: true
    });
    map.addControl(drawControl, 'top-left');

    map.once('load', () => {
      const drawInstance = drawControl.getTerraDrawInstance();
      if (drawInstance) {
        const geojson = [
          {
							id: '3f2504e0-4f89-11d3-9a0c-0305e82c3301',
                type: 'Feature',
                geometry: {
                  type: 'Polygon',
                  coordinates: [
                    [
                      [
                        5.783825208545238,
                        44.24016772359042
                      ],
                      [
                        5.043914894643905,
                        47.96908293794456
                      ],
                      [
                        5.1111794686347025,
                        49.50677418549904
                      ],
                      [
                        0.649296060563131,
                        50.64349197692914
                      ],
                      [
                        -1.3237981098398564,
                        47.66797156953183
                      ],
                      [
                        1.792793818410587,
                        44.79969551086995
                      ],
                      [
                        3.0483991995765507,
                        46.554076107477385
                      ],
                      [
                        5.783825208545238,
                        44.24016772359042
                      ]
                    ]
								]
                },
                  properties: {
                    mode: 'polygon',
                  }
              }
        ];
        drawInstance?.addFeatures(geojson);
      }
    });
  </script>
</body>
</html>

This code differs from the example in the mode (rectangle to polygon) and the coordinates.

Bug Screenshots

Bug System Information

Debian 12

Troubleshooting

To troubleshoot the issue, we can try the following:

Check the GeoJSON format: Ensure that the GeoJSON format is correct and that the coordinates are in the correct order.
Verify the TerraDraw instance: Make sure that the TerraDraw instance is properly initialized and that the addFeatures method is called correctly.
Check the map style: Ensure that the map style is set to a style that supports polygons.
Check the coordinates: Verify that the coordinates are within the valid range and that they are not overlapping.

Conclusion

In conclusion, the issue with rendering custom GeoJSON polygons using the addFeatures method in TerraDraw is likely due to a combination of factors, including incorrect GeoJSON format, improper TerraDraw instance initialization, or incorrect map style. By following the troubleshooting steps outlined above, users should be able to successfully load their custom polygons.

Recommendations

To avoid this issue in the future, we recommend the following:

Use a valid GeoJSON format: Ensure that the GeoJSON format is correct and that the coordinates are in the correct order.
Properly initialize the TerraDraw instance: Make sure that the TerraDraw instance is properly initialized and that the addFeatures method is called correctly.
Use a map style that supports polygons: Ensure that the map style is set to a style that supports polygons.
Verify the coordinates: Verify that the coordinates are within the valid range and that they are not overlapping.

By following these recommendations, users should be able to successfully load their custom polygons and avoid this issue in the future.

Additional Resources

For further assistance, please refer to the following resources:

TerraDraw documentation: https://terradraw.water-gis.com/docs/
Maplibre-gl documentation: https://docs.maplibre.org/maplibre-gl-js-docs/
GeoJSON documentation: https://geojson.org/
Q&A: Troubleshooting Custom GeoJSON Polygon Rendering with TerraDraw's addFeatures Method

Q: What is the issue with rendering custom GeoJSON polygons using the addFeatures method in TerraDraw?

A: The issue arises when attempting to load a custom GeoJSON polygon using the addFeatures method in TerraDraw. Despite following the example provided by TerraDraw, users are unable to render their custom polygon.

Q: What are the common causes of this issue?

A: The common causes of this issue include:

Incorrect GeoJSON format: Ensure that the GeoJSON format is correct and that the coordinates are in the correct order.
Improper TerraDraw instance initialization: Make sure that the TerraDraw instance is properly initialized and that the addFeatures method is called correctly.
Incorrect map style: Ensure that the map style is set to a style that supports polygons.
Incorrect coordinates: Verify that the coordinates are within the valid range and that they are not overlapping.

Q: How can I troubleshoot this issue?

A: To troubleshoot this issue, try the following:

Check the GeoJSON format: Ensure that the GeoJSON format is correct and that the coordinates are in the correct order.
Verify the TerraDraw instance: Make sure that the TerraDraw instance is properly initialized and that the addFeatures method is called correctly.
Check the map style: Ensure that the map style is set to a style that supports polygons.
Check the coordinates: Verify that the coordinates are within the valid range and that they are not overlapping.

Q: What are some best practices for rendering custom GeoJSON polygons using the addFeatures method in TerraDraw?

A: To avoid this issue in the future, follow these best practices:

Use a valid GeoJSON format: Ensure that the GeoJSON format is correct and that the coordinates are in the correct order.
Properly initialize the TerraDraw instance: Make sure that the TerraDraw instance is properly initialized and that the addFeatures method is called correctly.
Use a map style that supports polygons: Ensure that the map style is set to a style that supports polygons.
Verify the coordinates: Verify that the coordinates are within the valid range and that they are not overlapping.

Q: Where can I find additional resources for troubleshooting custom GeoJSON polygon rendering with TerraDraw's addFeatures method?

A: For further assistance, please refer to the following resources:

TerraDraw documentation: https://terradraw.water-gis.com/docs/
Maplibre-gl documentation: https://docs.maplibre.org/maplibre-gl-js-docs/
GeoJSON documentation: https://geojson.org/

Q: Can I get help with troubleshooting my specific issue?

A: Yes, please feel free to reach out to the TerraDraw support team for assistance with troubleshooting your specific issue. We will do our best to help you resolve the issue and get your custom GeoJSON polygon rendering correctly.

Q: What are some common mistakes to avoid when rendering custom GeoJSON polygons using the addFeatures method in TerraDraw?

A: Some common mistakes to avoid include:

Incorrect GeoJSON format: Ensure that the GeoJSON format is correct and that the coordinates are in the correct order.
Improper TerraDraw instance initialization: Make sure that the TerraDraw instance is properly initialized and that the addFeatures method is called correctly.
Incorrect map style: Ensure that the map style is set to a style that supports polygons.
Incorrect coordinates: Verify that the coordinates are within the valid range and that they are not overlapping.

By following these best practices and avoiding common mistakes, you should be able to successfully render your custom GeoJSON polygons using the addFeatures method in TerraDraw.