Introduction
In this guide, you will learn about the requirements for defining an area of interest (AOI) to search for geospatial datasets or task sensors with the UP42 platform. This is a crucial step, because using a correct AOI will ensure the successful ordering and smooth delivery of your datasets.
An AOI is a polygon that represents areas such as the boundary of a property, a water body or a forest. A polygon is a feature made of three or more vertices, where the last vertex is equal to the first.
Depending on the preferred UP42 option (the console, the Python SDK and the API), you can also use MultiPolygons. A MultiPolygon is a collection of minimum two polygons.
The table below summarizes the AOI requirements, which slightly differ for the 3 UP42 options.
| AOI rules | Console | Python SDK | API |
|---|---|---|---|
| File format | GeoJSON KML WKT | GeoJSON KML WKT Shapefile | GeoJSON |
| GeoJSON object | GeoJSON Feature | GeoJSON Feature GeoJSON FeatureCollection | GeoJSON Feature GeoJSON FeatureCollection |
| Z dimension | Not accepted | Not accepted | Not accepted |
| Geometry type | Polygon | Polygon MultiPolygon | Polygon |
| Coordinate system | WGS84 (EPSG 4326) | WGS84 (EPSG 4326) | WGS84 (EPSG 4326) |
| Coordinate system units | Decimal degrees | Decimal degrees | Decimal degrees |
The tables below summarize the general rules for creating valid Polygons and MultiPolygons.
| Polygon rules |
|---|
| The AOI should not be a shadock polygon (a). A shadock polygon is generated when the AOI intersects the image footprint (full scene) in more than one segment, thus creating more polygons. Shadock polygons can be fixed in two ways. The first solution is modifying the size of the AOI, so that the polygon intersects the image footprint in one segment. The second solution is splitting the AOI into more polygons, so that the user avoids increasing the size of the original shadock polygon and each polygon intersects the image footprint in one segment. |
| The first and last coordinate pairs are identical. |
| The polygon should not be a sliver polygon (b), i.e. with a very small area but with a very large perimeter. We recommend a minimum width of 100 meters. |
| The polygon should not contain any holes (c). |
| The polygon should not contain any self-intersections (d). |
| The polygon should not have an extremely complicated shape and too many vertices (e). We recommend a polygon with a maximum of 1000 vertices. If needed, a simplification algorithm should be applied (e.g. Douglas-Peucker). |
| Multipolygon rules |
|---|
| The multipolygon should not have duplicate features (f). |
| The multipolygon should not have a feature within a feature (g). |
| The polygons within a multipolygon should not overlap (h). |
