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.

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 doesn’t 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],
            [10.0026, 53.52],
            [10.1534, 53.58],
            [10.0026, 53.58]
          ]
        ]
      }
    }
  ]
}

  

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

• Remove the holes.
• Split the polygon and create 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],
            [10.0026, 53.52],
            [10.1534, 53.52],
            [10.1534, 53.58],
            [10.0026, 53.58]
          ]
        ]
      }
    }
  ]
}

  

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

• Expand the polygon to close any gaps causing multiple intersections with the full scene.
• Split the polygon and create multiple orders.

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.

For catalog orders, the console will draw a bounding box around a multipart polygon. Split your geometry and create individual orders for each polygon in your AOI, if needed.

If you’ve split a large polygon to meet AOI size limitations for a DEM collection and create several orders, the boundary edge pixels might not be fully captured, leading to data gaps. To prevent this, split polygons with an overlapping buffer.

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 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 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 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 large 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 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.
5. To save each of the split polygons, use the following steps:
   1. In the top navigation menu, click  Select Features and select the polygon you want to save.
   2. Inside the Layers panel on the left, right-click the geometry file and click Export → Save Selected Feature As.
   3. In Format, select an accepted file type. Go to File name and click the … button.
   4. Specify the file name and directory you want to save your geometry file to. Click OK.

If your geometry file has a large polygon that exceeds the AOI size limitations, and you want to ensure complete data coverage when ordering a DEM, split the polygon with an overlapping buffer 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 select the polygon you want to split.
3. In the top navigation menu, click Edit → Edit Geometry →  Split Features.
4. Draw a line through the polygon, and right-click to finish. Repeat this process to draw a second line adjacent to the first. This creates an overlapping buffer between the two parts.
5. Click  Select Features and select the buffer zone and one part of the split polygon.
6. Click Vector → Geoprocessing Tools →  Dissolve. In Input layer, select your geometry file and check the Selected features only checkbox.
7. Go to Dissolved and click the … button. Click Save to File. Specify the file name and directory you want to save your geometry file to. Click Save. Click Run.
8. Repeat steps 5–7 for the buffer zone and the remaining part of the split polygon.

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 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 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.