Level 1C relative geometric disparity metrics

This metadata file summarises the comparison between the different bands of an image. Tiepoints are collected for both bands.

Tiepoints are collected between different band combinations of an image. The distances between these corresponding tiepoints are measured.

note

The tiepoints collected during the quality assessment are collected independently of the tiepoints collected during processing.

The relative geometric verification metadata file is similar to the absolute geometric verification metadata file. However, the relative geometric verification metadata file contains measurements between the band combinations that were measured.

Sample file

Sample: LANDSAT-9_OLI_20220804T083603_20220804T083634_L1C_R1C1_GVER_REL.json

Property details

This section contains explanations on specific properties of the relative geometric disparity metrics file. All the properties are listed in a structured manner under the Reference section.

Pixel colour mappings

This section describes the pixelColorMappings property. This provides a legend to quantify disparities in colour ranges. This legend is used for the thumbnail referenced in imageName.

Measurements

Each relative geometric disparity metadata file contains a measurements section. This section is an array of measurements taken between two bands.

Property	Description
from	The name of the spectral band from where the disparity is measured
to	The name of the spectral band to where the disparity is measured
imageName	The filename of the preview image being generated containing a visual representation of the results of the geometric verification
disparitiesXYInMeters	A 2-dimensional array containing a set of disparity measurements (see below)
coordLonLat	A 2-dimensional array containing the coordinates of each disparity measurements (see below)
coverage	A percentage (out of 100) showing how much of the scene is covered by the geometric verification results

The combination of disparitiesXYInMeters and coordLonLat can be used to generate a map of each disparity point. The coordinates, in the sequence [longitude, latitude] denotes where the measurement was taken. The disparities is expressed in meters as the distance away from the coordinate point in the sequence [longitude, latitude].

Reference: relative geometric disparity metrics

The following reference describes the content of the relative geometric disparity metrics file.

• measurements (array): A list of disparity metrics grouped by individual bands.
  • Items (object)
    • coordsLonLat (array): The (longitude, latitude) coordinates of the evaluated tie-points.
      • Items (array)
        • Items (number, format: double)
    • coverage (integer, format: int32): Total percentange of the scene that could be evaluated by the tie-points.
    • disparitiesXYInMeters (array): A list of (x,y) disparities of the evaluated tie-points (in meters).
      • Items (array)
        • Items (number, format: double)
    • from (string): The band ID of the source used during comparison.
    • imageName (string): An illustration of the quality of all the tie-points evaluated on the image.
    • to (string): The band ID of the target used during comparison.
• pixelColorMappings (string): Mappings used to quantify disparities in color ranges (only for display purposes).