You can fine-tune your archive search on SkyFi to get better image results. Here's how filters like cloud cover, viewing angle, and overlap ratio work when using the POST /archives endpoint.
๐พ๐ก๐ค๐ช๐ ๐พ๐ค๐ซ๐๐ง๐๐๐ ๐๐๐ก๐ฉ๐๐ง: Use the "maxCloudCoveragePercent" parameter. For example, if you set "maxCloudCoveragePercent": 10, the API will only return images where the reported cloud cover is 10% or less. This is especially useful for optical imagery where clouds can obscure the ground. If you want any images regardless of clouds, you can set this to 100 (or simply omit it, as 100% is effectively the default maximum).
๐๐๐-๐๐๐๐๐ง ๐ผ๐ฃ๐๐ก๐ ๐๐๐ก๐ฉ๐๐ง: Use the "maxOffNadirAngle" parameter. This limits the camera angle of the satellite relative to directly overhead (nadir). A smaller angle (close to 0ยฐ) means the satellite was almost directly above the target, which generally yields less distortion and better image quality. If you set, say, "maxOffNadirAngle": 20, you will get images taken from fairly overhead views (within 20 degrees of vertical). Higher angles (oblique shots) can cover your area but with more perspective distortion and possibly lower resolution on the ground.
๐๐๐ฃ๐๐ข๐ช๐ข ๐๐ซ๐๐ง๐ก๐๐ฅ: Another related filter is "minOverlapRatio". This ensures that the image at least covers a certain fraction of your AOI. For example, "minOverlapRatio": 0.5 would only return images where at least 50% of your AOI is within the image footprint. This helps avoid cases where an image marginally intersects your area.
๐๐ค๐ง๐ฉ๐๐ฃ๐ (๐๐ข๐ฅ๐ก๐๐๐๐ฉ) : The API does not explicitly let you sort results by these criteria in the request, but you can retrieve all matches (up to the page size) and then client-side choose images with the best cloud/angle if multiple are available. Often, archive search results will include these fields so you can pick the best image for your needs.
By using these filters, you can fine-tune your search to get only high-quality imagery (clear and near-nadir). Keep in mind that stricter filters may result in fewer or even zero results if the criteria are hard to meet in the given time range and area. It may be useful to start with looser criteria (e.g., 50% clouds, 30ยฐ off-nadir) and then narrow down if too many results are returned.
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