Rules for creating geometries

To successfully place tasking or catalog orders, your geometries must follow certain rules:

• Check that your geometries conform to the limitations specified for a particular tasking or catalog collection:

  • In Input, check whether the collection accepts AOIs or POIs.
  • In AOI size, check the upper and lower bounds of AOI sizes.
  • In Width and length, check the permissible ranges for the width and length of your AOI.

• Check that your geometries don’t contain more than 999 vertices.

• If you’re uploading your geometry as a file, make sure that it uses a supported file format.

• Check that your geometry uses a geographic coordinate system. The coordinates must be in degrees rather than units of measurement such as meters or feet.

• Verify that your geometry contains valid features.

To place an order, geometries must meet certain validity conditions.

Features that contain duplicate vertices aren’t valid. These are features with one or more vertices that occur multiple times. Check for duplicate vertices and remove the duplicates, if needed.

Note that this rule does not apply to the first and last vertices. They must be identical.

    {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [10.0026, 53.58],
            [10.0026, 53.52], // Duplicate vertices
            [10.0026, 53.52], // Duplicate vertices
            [10.1534, 53.58],
            [10.0026, 53.58]
          ]
        ]
      }
    }
  ]
}

  

    {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [10.0026, 53.58],
            [10.0026, 53.52],
            [10.1534, 53.52],
            [10.1534, 53.58],
            [10.0026, 53.58]
          ]
        ]
      }
    }
  ]
}

  

Polygons with more than 999 vertices aren’t valid. Check the number of vertices and reduce it, if needed.

Polygons with three or fewer vertex positions aren’t valid. Valid polygons have three or more unique vertices. Check the number of vertices and add them, if needed.

    {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [10.0026, 53.58], // 1. Opening vertex
            [10.0026, 53.52], // 2. Unique vertex
            [10.0026, 53.58]  // 3. Closing vertex
          ]
        ]
      }
    }
  ]
}

  

    {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [10.0026, 53.58], // 1. Opening vertex
            [10.0026, 53.52], // 2. Unique vertex
            [10.1534, 53.58], // 3. Unique vertex
            [10.0026, 53.58]  // 4. Closing vertex
          ]
        ]
      }
    }
  ]
}

  

Polygons that contain holes aren’t valid. Check for holes and fix them in one of the following ways:

• Remove the holes.
• Separate any multipart polygons and make multiple orders.

Line geometries aren’t valid. The feature type must be polygon or point. Convert the geometry to an allowed type.

Polygons without identical endpoints — first and last vertices — don’t form a closed geometry and aren’t valid.

    {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [10.0026, 53.58], // Opening endpoint
            [10.0026, 53.52],
            [10.1534, 53.52],
            [10.1534, 53.58]  // Mismatched closing endpoint
          ]
        ]
      }
    }
  ]
}

  

    {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [10.0026, 53.58], // Opening endpoint
            [10.0026, 53.52],
            [10.1534, 53.52],
            [10.1534, 53.58],
            [10.0026, 53.58]  // Matching closing endpoint
          ]
        ]
      }
    }
  ]
}

  

For catalog orders, multipart polygons aren’t valid. The console will only return images intersecting your geometry’s bounding box, or the total geographic coverage of the multipart polygon provided. Separate your geometry and create individual orders for each polygon in your AOI, if needed.

A polygon that intersects a catalog full scene in more than one place isn’t valid. Fix it in one of the following ways:

• Split the polygon. The console will accept the multipart polygon and return catalog full scenes intersecting your geometry’s bounding box, or the total geographic coverage of the multipart polygon provided.
• Separate the multipart polygon and make multiple orders.
• Extend the polygon to close any gaps causing multiple intersections with the full scene.

Polygons with self-intersections aren’t valid. These are polygons whose edges cross each other. Check for self-intersections and remove them, if needed.

Sliver polygons aren’t valid. These are polygons with a very small area but with a very large perimeter. Your AOI geometry must meet a tasking or catalog collection’s minimum width criteria to be considered valid. Fix it in one of the following ways:

• Check for slivers and modify them.
• Expand the polygon.

You can resolve common geometry issues using QGIS, a free open-source GIS software. To do that, download and install QGIS. After the installation, open QGIS and then drag and drop your geometry files to edit them. For more information on how to use QGIS, see the QGIS documentation.

1. In the top navigation menu, click Project →  Properties.
2. Inside the General panel, go to Measurements → Units for area measurement and select Square Kilometers. Click OK.
3. To display the Identify Results panel, in the top navigation menu, click View →  Identify Features.
4. Select the polygons you want to measure.
5. Inside the Identify Results panel on the right, click the polygon name and expand (Derived) to check the following:
   • In the Area (Ellipsoidal) field, check the size.
   • In the Vertices field, check the number of vertices.

Check for duplicate vertices, sliver polygons, self-intersections, and holes using the following steps:

1. To enable the geometry checking tool, in the top navigation menu, click Plugins → Manage and Install Plugins. Search for Geometry Checker and select the checkbox. Click Close.
2. In the top navigation menu, click Vector →  Check Geometries.
3. In Input vector layers, select your geometry file.
4. Check for not valid features as follows:
   • To check for self-intersections, in Geometry validity, select Self intersections.
   • To check for duplicate vertices, in Geometry validity, select Duplicate nodes.
   • To check for holes, in Geometry properties, select Polygons and multipart polygons may not contain any holes.
   • To check for sliver polygons, in Geometry conditions, select No sliver polygons.
5. To modify your original geometry file, in Output vector layers, select Modify input layer.
6. Click Run to see the results of the geometry check.

If your geometry isn’t an allowed feature type, change its type.

1. To display the Processing Toolbox, go to the top navigation menu and click Processing →  Toolbox.
2. In the Processing Toolbox search bar on the right, search for Convert geometry type and select it.
3. In Input layer, select your geometry file.
4. In New geometry type, select Polygons. Click Run and then Close.
5. Inside the Layers panel on the left, right-click on the new geometry file and click Export → Save Feature As.
6. In Format, select an accepted file type. Go to File name and click the … button.
7. Specify the file name and directory you want to save your geometry file to. Click OK.

If your geometry file has an unresolved geometry issue, you can generate a rectangular polygon based on your geometry’s bounding box, or geographic coverage. Note this will increase the AOI size.

1. To display the Processing Toolbox, go to the top navigation menu and click Processing →  Toolbox.
2. In the Processing Toolbox search bar on the right, search for Extract layer extent and select it.
3. In Input layer, select your geometry file. Click Run and then Close.
4. Inside the Layers panel on the left, right-click on the new geometry file and click Export → Save Feature As.
5. In Format, select an accepted file type. Go to File name and click the … button.
6. Specify the file name and directory you want to save your geometry file to. Click OK.

If your geometry file has a polygon that exceeds the AOI size limitations, has a hole, has self-intersections, is a sliver polygon, or intersects an image footprint in more than one place, you can split the polygon using the following steps.

1. To enable editing, in the top navigation menu, click Layer →  Toggle Editing.
2. In the top navigation menu, click  Select Features and then select the polygon you want to split.
3. In the top navigation menu, click Edit → Edit Geometry →  Split Features. Draw a line through the polygon, and right-click. This will split your polygon.
4. To modify your original geometry file, in the top navigation menu, click Layer →  Toggle Editing and Save.

If your geometry file is a multipart polygon, you can generate an individual file for each polygon using the following steps.

1. In the top navigation menu, click Vector → Data Management Tools → Split Vector Layer.
2. In Input layer, select your geometry file.
3. In Advanced Parameters → Output filetype, select an accepted file type.
4. In Output directory, specify the directory you want to save your geometry files to. Click Run.

If your geometry file has a polygon with more than 999 vertices, you can reduce the number of vertices using the following steps:

1. To enable editing, in the top navigation menu, click Layer →  Toggle Editing.
2. In the top navigation menu, click Edit → Edit Geometry →  Simplify Feature and then select the polygon you want to simplify.
3. In Method, select Simplify by Distance and change values for Tolerance until the number of vertices goes below 999. Click OK.
4. To modify your original geometry file, in the top navigation menu, click Layer →  Toggle Editing and Save.

If your geometry file has a polygon with a hole, you can remove the hole using QGIS. Note this will increase the AOI size.

1. To display the Processing Toolbox, go to the top navigation menu and click Processing →  Toolbox.
2. In the Processing Toolbox search bar on the right, search for Delete holes and select it.
3. In Input layer, select your geometry file. Click Run and then Close.
4. Inside the Layers panel on the left, right-click on the new geometry file and click Export → Save Feature As.
5. In Format, select an accepted file type. Go to File name and click the … button.
6. Specify the file name and directory you want to save your geometry file to. Click OK.

If your geometry file has duplicate vertices or self-intersections, you can use the following steps:

1. To display the Processing Toolbox, go to the top navigation menu and click Processing →  Toolbox.
2. In the Processing Toolbox search bar on the right, search for Remove duplicate vertices and select it.
3. In Input layer, select your geometry file. Click Run and then Close.
4. Inside the Layers panel on the left, right-click on the new geometry file and click Export → Save Feature As.
5. In Format, select an accepted file type. Go to File name and click the … button.
6. Specify the file name and directory you want to save your geometry file to. Click OK.