Pixxel Imagery 101

  • Effective Ground Resolved Distance (GRD)

    Firefly imagery is sampled at 5.4 m ground sample distance (GSD). Effective ground resolved distance (GRD) may be coarser than the GSD and can vary by satellite, atmospheric conditions, processing state, and capture mode. Customers with resolution-critical requirements should contact Pixxel directly for current performance data before procurement

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  • What imagery product levels does Pixxel provide?

    Pixxel offers the following imagery product levels:

    Product Level Description Availability Delivery 
    L2A Bottom-of-Atmosphere (BOA) reflectance Default offering.  Available on Aurora.
    L1C Top-of-Atmosphere (TOA) reflectance Available on demand  Only cloud transfer available (AWS, Azure or GCS)
    L1B Geometrically corrected data Available on demand  Only cloud transfer available (AWS, Azure or GCS)

    If you require L1C or L1B data, please contact support@pixxel.space to request access.

     

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  • Atmospheric Correction - piSOFIT model

    piSOFIT is Pixxel’s customized implementation of NASA JPL’s open-source ISOFIT (Imaging Spectrometer Optimal Fitting) model, optimized for Firefly and Honeybee hyperspectral data.

     

    Methodology

    • Radiative Transfer Modeling: piSOFIT uses a neural-network-based MODTRAN emulator derived from 6S to model the interaction of solar radiation with the atmosphere and Earth’s surface.

    • Optimal Estimation Inversion: The workflow iteratively adjusts atmospheric parameters (e.g., water vapor, aerosols) and surface reflectance to minimize residuals between observed at-sensor radiance and modeled radiance using a Levenberg-Marquardt optimization approach.

    • Bayesian Priors & Uncertainty Quantification: Prior information about atmospheric and surface conditions is incorporated into the inversion, providing improved retrieval stability and per-pixel uncertainty estimates.

    • Superpixel Segmentation & Empirical Refinement: piSOFIT segments images into spectrally similar superpixels, solves atmospheric parameters at the superpixel level, and applies an empirical line adjustment to refine surface reflectance for each pixel.

    For more technical details, visit the Isofit documentation.

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  • File naming convention for Pixxel Imagery

    All files in the delivery follow a consistent naming pattern:

    XXnn_YYYYMMDD_aaabbccc_imageID_LnX.<filetype>

     

    Where:

    • XXnn: Satellite identifier (e.g., FF01 for Firefly 1)
    • YYYYMMDD: Acquisition date (first instance) and product creation date (second instance).
    • aaa: Average spatial resolution
    • bb: Reserved
    • ccc: Number of spectral bands in the delivered image.
    • imageID: Unique six-digit image identifier.
    • LnX: Processing level (e.g. L1C, L2A)
    • filetype: File (e.g., .tif, .mask.tif, .geojson, .jpeg, .hdr, .xml).
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  • Pixxel Imagery Overview

    Product Bundles:

    1. L2A : Bottom of Atmosphere (BOA) reflectance (default option unless otherwise specified)
    2. L1C : Top of Atmosphere (TOA) reflectance (available on request)
    3. L1B : Geometrically Corrected Radiance (available on request)

    Product Processing:

    Name DescriptionProduct Level
    Bottom of Atmosphere (BOA) reflectance

    This is radiometric, geometric, and atmospheric (aerosol and watervapor) corrected BOA reflectance data. The image is orthorectified and projected in UTM projection (WGS84 datum). The data is available in a geoTIFF file format (accompanied by additional metadata).

    The pixel reflectance values are linearly scaled between 0 - 50000.Thus to convert the image to 0-1 reflectance range, all the pixel values must be divided by 50000

    		L2A
    Top of Atmosphere (TOA) reflectance

    This is radiometric, and geometric corrected TOA reflectance data.The image is orthorectified and projected in UTM projection (WGS84 datum). The data is available in a geoTIFF file format (accompanied by additional metadata).

    The pixel reflectance values are linearly scaled between 0 - 50000. Thus to convert the image to 0-1 reflectance range, all the pixel values must be divided by 50000.

    		L1C (available on request)
    Geometrically Corrected Radiance

    This is a geometrically corrected radiance dataset (also termed at-sensor radiance). Geolocation is computed photogrammetrically, yielding good band-to-band registration. The image is orthorectified using a customer-requested projection. The data is available in a geoTIFF file format (accompanied by additional metadata). This level may be available on request.

    The pixel values are not scaled and the values have radiance units -W⋅m-2⋅sr-1⋅μm-1

    		L1B (available on request)

     

    Image Delivery Package:

    Pixxel imagery products are delivered as a structured set of files. Each product delivery includes:

    • Primary Image Files: GeoTIFF containing the capture area at the specified processing level.

    • Quality Mask File: GeoTIFF mask identifying cloud, cloud shadow, water, and other quality flags at

      bit-encoded layers.

    • Footprint Polygon: GeoJSON file representing the exact acquisition footprint.

    • Bounding Box Polygon: GeoJSON file providing the rectangular bounding extent of the acquisition.

    • ENVI Header File: .hdr file providing band, wavelength, and projection information for direct hyperspectral processing.

    • Thumbnail Preview: RGB JPEG quicklook for rapid scene visualization.

    • ReadMe File: A text document describing package contents, filename conventions, quality mask bit

      definitions, and processing notes

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