Umbra's standard 5km x 5km Spotlight product ensures consistent high-quality imaging across the entire imaged area. However, for customers prioritizing larger ground coverage, Umbra offers Extended Area Processing with capabilities up to 5km x 10km via the Canopy API. This comes with a trade-off, as the product quality diminishes outside the standard area, with factors like increased file size, variable range resolution, decreased terrain-to-noise ratio, beam roll-off, and ambiguity artifacts. These artifacts include visible antenna patterns, decreased brightness towards the edges, and the appearance of fuzzy objects.

To create a Task with an Extended Scene Size, set Task.spotlightConstraints.sceneSize to a value other than 5x5_km. See Create Feasibility and Create Task.

Trade-Offs

File Size

Extended area data products are up to 10x larger than the standard 5km x 5km product.

Variable Range Resolution

Outside the standard 5km x 5km area, the range resolution may degrade and become coarser.

Decreased Terrain-to-Noise Ratio

Outside the standard 5km x 5km area, the noise floor raises resulting in a decrease in terrain-to-noise ratio (TNR). At the extreme, parts of the image may be completely black.

Beam Roll-Off

For very large processing, a visible antenna pattern could be present within the image. The tell-tale sign of this artifact is vignetting, a reduction of an image's brightness away from the center of the image.

Ambiguity Artifacts

In an extended area product, large, squarish fuzzy objects might appear at the edges of the scene.

Examples

Standard Product

A notional standard 10km x 10km product is shown. The white dashed line indicates the footprint of a 5km x 5km Spotlight image. The image below exhibits none of the artifacts outlined above:

Extended Area Product

A notional extended area product is shown below. Artifacts outlined above are present:

1. Ambiguities can be seen on the scene edges
2. Beam Roll-Off is present as the brightness decreases away from the scene center.
3. The terrain-to-noise ratio decreases as a result of the beam roll-off.