Rules for creating geometries

Check that your geometry is accepted by the platform.


Geometry checklist

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.

Not valid features

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

Duplicate vertices

Catalog and tasking

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.

Not valid

This polygon contains duplicates and isn’t valid.

An example of a polygon with duplicate vertices

JSON

    {
  "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]
          ]
        ]
      }
    }
  ]
}
  

Valid

This polygon contains unique vertices and is valid.

An example of a polygon with unique vertices

JSON

    {
  "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]
          ]
        ]
      }
    }
  ]
}
  

Excessive vertices

Catalog and tasking

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

Not valid

This polygon contains more than 999 vertices and isn’t valid.

An example of a polygon with more than 999 vertices

Valid

This polygon contains fewer than 999 vertices and is valid.

An example of a polygon with fewer than 999 vertices

Few vertices

Catalog and tasking

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.

Not valid

This polygon contains less than three positions or four vertices and isn’t valid.

An example of a polygon with less than three positions

JSON

    {
  "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
          ]
        ]
      }
    }
  ]
}
  

Valid

This closed polygon contains three positions and four vertices and is valid.

An example of a polygon with three unique positions

JSON

    {
  "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
          ]
        ]
      }
    }
  ]
}
  

Holes

Catalog and tasking

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.

Not valid

This polygon contains a hole and isn’t valid.

An example of a polygon with a hole

Valid

The polygon was split into two valid polygons.

An example of split polygons

Lines

Catalog and tasking

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

Not valid

This enclosed line isn’t a valid geometry type.

An example of a not valid line

Valid

The line was converted into a valid polygon.

An example of a valid polygon

Mismatched endpoints

Catalog and tasking

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

Not valid

This polygon has different first and last coordinates and isn’t valid.

An example of a polygon with different endpoints

JSON

    {
  "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
          ]
        ]
      }
    }
  ]
}
  

Valid

The polygon was edited so the first and last coordinates are the same.

An example of a polygon with identical endpoints

JSON

    {
  "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
          ]
        ]
      }
    }
  ]
}
  

Multipart polygons

Catalog

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.

Not valid

This multipart polygon isn’t valid.

An example of a not valid multipart polygon

Valid

The geographic bounds are valid.

An example of the valid geographic bounds

Full scene intersections

Catalog

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.

Not valid

This polygon intersects the catalog full scene in two places.

An example of multiple intersections with a full scene

Valid

The polygon was edited to avoid multiple intersections.

An example of a single intersection with a full scene

Self-intersections

Catalog and tasking

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

Not valid

This polygon contains a self-intersection and isn’t valid.

An example of a polygon with multiple self-intersections

Valid

This polygon contains no self-intersections and is valid.

An example of a polygon without any self-intersections

Sliver polygons

Catalog and tasking

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.

Not valid

This polygon has a very small width and large perimeter and isn’t valid.

An example of a sliver polygon

Valid

This polygon has a balanced width to perimeter ratio and is valid.

An example of a valid polygon

Correcting geometries in QGIS

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.

Check AOI size and number of vertices

  1. In the top navigation menu, click ProjectQGIS properties inline-icon Properties.
  2. Inside the General panel, go to MeasurementsUnits for area measurement and select Square Kilometers. Click OK.
  3. To display the Identify Results panel, in the top navigation menu, click ViewQGIS identify features inline-icon 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 not valid features

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 PluginsManage and Install Plugins. Search for Geometry Checker and select the checkbox. Click Close.
  2. In the top navigation menu, click VectorQGIS check geometries inline-icon 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.

Convert geometry

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 ProcessingQGIS toolbox inline-icon 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 ExportSave 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.

Extract geometry coverage

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 ProcessingQGIS toolbox inline-icon 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 ExportSave 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.

Split a polygon

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 LayerQGIS toggle editing inline-icon Toggle Editing.
  2. In the top navigation menu, click QGIS select features inline-icon Select Features and then select the polygon you want to split.
  3. In the top navigation menu, click EditEdit GeometryQGIS split features inline-icon 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 LayerQGIS toggle editing inline-icon Toggle Editing and Save.

Separate multipart polygons

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 VectorData Management ToolsSplit Vector Layer.
  2. In Input layer, select your geometry file.
  3. In Advanced ParametersOutput filetype, select an accepted file type.
  4. In Output directory, specify the directory you want to save your geometry files to. Click Run.

Reduce the number of vertices

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 LayerQGIS toggle editing inline-icon Toggle Editing.
  2. In the top navigation menu, click EditEdit GeometryQGIS simplify feature inline-icon 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 LayerQGIS toggle editing inline-icon Toggle Editing and Save.

Remove holes

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 ProcessingQGIS toolbox inline-icon 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 ExportSave 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.

Remove duplicate vertices

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 ProcessingQGIS toolbox inline-icon 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 ExportSave 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.