Choose Area of Interest
The Area of Interest (AOI) defines the geographical region for which you wish to receive data. ClearSKY offers two distinct ordering types to accommodate different needs: Polygon and Tile Ordering.
In polygon ordering, the AOI must be defined as a GeometryCollection containing one or multiple POLYGONs and/or MULTIPOLYGONs. These geometries are used directly in the ordering process, provided they meet the geometry limitations described below. If you are interested in different image frequencies for different geometries, we recommend placing multiple orders to fully control the image dates ordered for the different AOIs.
Polygon ordering now gives substantially more freedom for smaller fields and irregular boundaries. In most cases, you can submit the geometry you actually want ordered rather than expanding it to a bounding box first.
Using Single- or MultiPolygons
Single Polygons
When you provide a GeometryCollection with single POLYGONs, each Polygon is evaluated separately. This applies to both the minimum billable area and the geometry checks. This can be beneficial for covering diverse and distributed areas such as separate crop fields.
For each Polygon:
- the submitted geometry is used directly;
- the minimum billable area is 0.5 km²;
- the geometry area must be at least 5% of its own bounding box area;
- each side of the bounding box must be longer than 150 meters.
MultiPolygons
When you provide a MULTIPOLYGON within the GeometryCollection, the extent is evaluated based on the combined area of all Polygons within that MultiPolygon. This approach is advantageous when you have multiple small areas in close proximity, as it can help meet the minimum billable area more efficiently than submitting each area as a separate Polygon.
For each MultiPolygon:
- the minimum billable area is applied to the combined MultiPolygon area;
- the 5% rule is evaluated against the bounding box of the full MultiPolygon;
- each side of that bounding box must be longer than 150 meters.
This means a MultiPolygon can be useful for grouping nearby small areas, but it is not a way to bypass sparse or widely scattered geometries. If the combined shape covers too little of its bounding box, it will not be accepted as submitted.
Example Scenarios
The most useful examples for polygon ordering are now the cases that clarify what is accepted as submitted and what should be adjusted before placing an order.
In the maps below, blue shows the submitted geometry and red shows the bounding box used for validation where relevant. The dimensions and areas are approximate and are included only to illustrate the rule. Validation is performed after conversion from EPSG:4326 to the relevant local UTM EPSG.
Example 1: Small Polygon That Is Still Accepted
A single Polygon smaller than 0.5 km² is still accepted, provided it meets the 5% bounding box rule and the 150 meter minimum side length rule. In this case, the order is billed at the minimum billable area of 0.5 km².
This is useful to show because smaller fields no longer need unnecessary expansion simply to reach the minimum billable threshold.
Submitted Geometry:
GEOMETRYCOLLECTION (
POLYGON ((
9.840000 56.770000,
9.846542 56.770000,
9.846542 56.773592,
9.840000 56.773592,
9.840000 56.770000
))
)
Blue shows the submitted geometry.
Result: Accepted. The Polygon is approximately 400 m x 400 m with an area of approximately 0.16 km². It satisfies the geometry checks and is billed at the minimum billable area of 0.5 km².
Example 2: Polygon Rejected Due to Minimum Side Length
A Polygon is not accepted if one side of its bounding box is shorter than 150 meters. This commonly happens for very narrow strips or long, thin geometries.
A useful example here is a field that is long enough in one direction, but too narrow in the other. Even if the total area looks reasonable at first glance, the geometry does not pass validation because the bounding box is too narrow.
Submitted Geometry:
GEOMETRYCOLLECTION (
POLYGON ((
9.852000 56.770000,
9.853962 56.770000,
9.853962 56.777184,
9.852000 56.777184,
9.852000 56.770000
))
)
Blue shows the submitted geometry.
Result: Rejected. The Polygon is approximately 120 m x 800 m. One side of its bounding box is shorter than the required minimum of 150 meters.
Example 3: Polygon Rejected Due to the 5% Rule
A complex Polygon is not accepted if its area is less than 5% of the area of its own bounding box. This prevents extremely sparse or highly elongated shapes from being submitted at very low coverage relative to their extent.
A useful example here is an irregular Polygon with a large bounding box but only a very small filled area inside that box.
Submitted Geometry:
GEOMETRYCOLLECTION (
POLYGON ((
9.840000 56.780000,
9.856354 56.788980,
9.856354 56.788262,
9.840000 56.780000
))
)
Bounding Box Used for Validation:
GEOMETRYCOLLECTION (
POLYGON ((
9.840000 56.780000,
9.856354 56.780000,
9.856354 56.788980,
9.840000 56.788980,
9.840000 56.780000
))
)
Blue shows the submitted geometry and red shows the bounding box used for validation.
Result: Rejected. The Polygon covers only approximately 4% of its own bounding box area, which is below the required minimum of 5%.
Example 4: MultiPolygon Accepted Because the Combined Geometry Is Useful
A MULTIPOLYGON is useful when you have several small areas in close proximity. If the combined MultiPolygon area reaches the minimum billable area more efficiently, and the full MultiPolygon still satisfies the 5% rule and 150 meter minimum side length rule, it can be a practical way to order nearby areas together.
This is useful to show because the minimum billable area is evaluated per Polygon or per MultiPolygon, not per individual ring or piece.
Submitted Geometry:
GEOMETRYCOLLECTION (
MULTIPOLYGON (
((9.855000 56.782000, 9.858271 56.782000, 9.858271 56.783796, 9.855000 56.783796, 9.855000 56.782000)),
((9.859579 56.782000, 9.862850 56.782000, 9.862850 56.783796, 9.859579 56.783796, 9.859579 56.782000)),
((9.857290 56.783078, 9.860560 56.783078, 9.860560 56.784874, 9.857290 56.784874, 9.857290 56.783078))
)
)
Bounding Box Used for Validation:
GEOMETRYCOLLECTION (
POLYGON ((
9.855000 56.782000,
9.862850 56.782000,
9.862850 56.784874,
9.855000 56.784874,
9.855000 56.782000
))
)
Blue shows the submitted MultiPolygon and red shows the bounding box used for validation.
Result: Accepted. The combined MultiPolygon area is approximately 0.12 km² and covers approximately 78% of its bounding box area. This is a practical way to group multiple nearby small areas into one order geometry.
Example 5: MultiPolygon Rejected Due to the 5% Rule
A MULTIPOLYGON is not accepted as submitted if the individual polygons are too far apart or too sparse relative to the bounding box of the full MultiPolygon. In that case, the combined shape may fail the 5% rule, even if each smaller piece would have been acceptable on its own.
A useful example here is several small polygons spread across a wide area. The total geometry may look reasonable at first glance, but the bounding box becomes too large relative to the combined filled area.
Submitted Geometry:
GEOMETRYCOLLECTION (
MULTIPOLYGON (
((9.840000 56.795000, 9.843271 56.795000, 9.843271 56.796796, 9.840000 56.796796, 9.840000 56.795000)),
((9.861260 56.795000, 9.864531 56.795000, 9.864531 56.796796, 9.861260 56.796796, 9.861260 56.795000)),
((9.850630 56.801286, 9.853901 56.801286, 9.853901 56.803082, 9.850630 56.803082, 9.850630 56.801286))
)
)
Bounding Box Used for Validation:
GEOMETRYCOLLECTION (
POLYGON ((
9.840000 56.795000,
9.864531 56.795000,
9.864531 56.803082,
9.840000 56.803082,
9.840000 56.795000
))
)
Blue shows the submitted MultiPolygon and red shows the bounding box used for validation.
Result: Rejected. The combined MultiPolygon covers only approximately 4.5% of its bounding box area, which is below the required minimum of 5%.
For many practical cases, MULTIPOLYGONs are now especially useful for grouping nearby smaller areas without the overhead that previously came from bounding-box-only ordering.
Geometry Limitations for Polygon Ordering
All geometries are accepted without modification to shape, provided the following conditions are met:
- The minimum billable area is 0.5 km². Smaller areas are accepted but billed as 0.5 km².
- For complex geometries, the geometry area must be at least 5% of the area of its bounding box.
- Each side of the bounding box must be longer than 150 meters.
For POLYGONs, these checks are applied per Polygon. For MULTIPOLYGONs, these checks are applied to the full MultiPolygon.
All geometries must adhere to EPSG:4326 and will be converted to local UTM EPSG (EPSG:326XX or EPSG:327XX) for processing.