The process for ordering AI Layer Raster Export (Offline Delivery) is:
- Review the currently available AI Layers in the AI Layer Glossary.
- Discuss your needs with your Account Manager. Your Account manager may recommend a different delivery mode.
- Submit an order, where you must provide:
- AOI: An Area of Interest (AOI), ideally as a geospatial polygon (e.g. GeoJSON, KML or shapefile), or the name of a well-defined government boundary.
- AI Layer Selection: A list of the layers you wish to purchase (including any composite layers - we can combine multiple layers into a single layer; combining Asphalt and Concrete into a single impervious surfaces layer is a common request).
- Date Selection: Any information about the date(s) you would like processed in your AOI (most recent, or a particular year, season, or date). You can ask us to process an AI Layer on any of our imagery that has been published through MapBrowser or our imagery APIs.
- Map Projection: A map projection - by default, we produce EPSG:3857 tiles, however, we can convert these to a local projection of your choosing.
- Resolution: The raster AI Layers are produced natively at zoom level 21 in EPSG:3857. That means the highest meaningful resolution to request is approximately 7.5cm / pixel. Many customers prefer 30-50cm per pixel to reduce file sizes and make the processing easier to manage.
- Review the Order Summary: Attached to your quote will be a detailed order summary reflecting the above information, and what will be delivered. Please review it carefully to ensure it is correct.
- An email will be sent with instructions on how to download it once it is ready.
- AI Raster offline is delivered as a link to a set of GeoTIFF files which are jpeg compressed and split into tiles (depending on the size of the AOI and resolution). The link also contains a PDF describing the data, and a shapefile of the tile boundaries if the AOI has been split into multiple tiles.
- Each pixel is represented by a 0-255 (uint8) value. 255 corresponds to an estimated 100% probability that the definition is present on that pixel (i.e. definitely present); 0 corresponds to 0% probability (i.e. definitely not present).
- Most users will want to perform a threshold to create a binary layer; 127 (50% probability) is a good place to start, but it depends on the use case.
- Where the AOI overlaps multiple imagery surveys, you will receive multiple sets of GeoTIFF files that overlap (we do not blend the surveys). There is a NODATA layer in the output to allow you to blend them as you see fit. This depends on the use case, and how much time has elapsed between the survey dates.
- We can blend multiple different AI Layers into a single one for you (such as asphalt and concrete blended into an impervious surface layer), by statistically combining the probabilities on each layer.
- You can choose a resolution up to 7.5cm/pixel, and a map projection.
This GeoTIFF is an example of a single tile from within a delivery. This comes zipped with the other tiles from your AOI, and associated explanatory files: