The process fuses the higher-resolution panchromatic band with lower-resolution multispectral bands of a STAC item from an optical collection, using the Brovey method. The result is a GeoTIFF file with an upsampled spatial resolution.
Most often, optical collections produce the following bands:
- A panchromatic band with a high spatial resolution but a low spectral resolution
- Several multispectral bands with a low spatial resolution but a high spectral resolution
The fusion that pansharpening provides allows you to benefit from the complementary qualities of panchromatic and multispectral bands. The result is a pansharpened reflectance product.
Before pansharpening
After pansharpening
See more on the marketplace.
The STAC item should be CNAM-compatible. CNAM-compatible data meets both criteria:
- The data was added to storage starting in 2023.
- The data comes from a supported collection.
The STAC item should come from an optical collection. The following categories of collections are compatible:
- Tasking:
- Optical satellite imagery
- Optical aerial imagery
- Catalog:
- Optical satellite imagery
- Optical aerial imagery
The STAC item should have panchromatic and multispectral bands. To check, whether the chosen collection provides the necessary bands, see Spectral bands.
Required parameters
Input imagery
You need to specify the STAC items you want to apply the process to.
Output title
You need to specify the title of the output objects. This title will be assigned to the resulting STAC item and STAC collection.
Optional parameters
Grey weights
You can specify the weights for multispectral bands or use automatically optimized weights by not defining them. Depending on the input STAC item, the algorithm either uses sensor-optimized weights or, if this data is not available, generates new optimal weights.
The weighted Brovey method, applied for this algorithm, uses the following values:
- The pseudo panchromatic intensity. It is derived from a weighted average of the multispectral bands. Each multispectral band may contribute differently to this average, and the weights reflect their importance in approximating the panchromatic data.
- The real panchromatic intensity. It is the actual panchromatic intensity data that serves as a reference value.
The output value of a multispectral band is computed as follows:
A sample input payload for the process
JSON
{
"inputs": {
"title": "Pansharpened SPOT imagery over Germany",
"item": "https://api.up42.com/v2/assets/stac/collections/21c0b14e-3434-4675-98d1-f225507ded99/items/23e4567-e89b-12d3-a456-426614174000",
"greyWeights": [
{
"band": "blue",
"weight": 0.2
},
{
"band": "green",
"weight": 0.34
},
{
"band": "red",
"weight": 0.23
}
]
}
}
| Parameter | Overview |
|---|---|
inputs.title | object / required The title of the output objects: STAC item and STAC collection. |
inputs.item | object / required The STAC item link in the following format: https://api.up42.com/v2/assets/stac/collections/{collection-id}/items/{item-id} |
inputs.greyWeights | array of objects The weight factors by which spatial details of multispectral bands are scaled.
|
inputs.greyWeights.band | string / required if Required if greyWeights is used.The name of the band from the STAC asset with the ["data", "multispectral"] roles. |
inputs.greyWeights.weight | float / required if Required if greyWeights is used.The multiplication value that lets you modulate the influence of multispectral bands on the final image. The range of allowed values spans from -1 to 1. |
