The value of this field should be related to the spatial resolution at the sensor, rather than the pixel size of images after orthorectification, pansharpening, or scaling.
In practice, I believe the value of gsd has come from its indication of the spatial resolution of rasters, and that folks have come to expect the gsd and spatial resolution values to match up. For example, see the discussion on this stactools PR - https://github.com/stac-utils/stactools/pull/88#issuecomment-816921490
I think the case where raster data spatial resolution does not match the sensor resolution (e.g. in the case of the Sentinel 2 band downsampling, as discussed in that PR) will be confusing to users, and may deserve a rethink of how we want GSD to be defined.
I see how users are utilizing GSD as an indication of spatial resolution; are there use cases where asset GSD is being used effectively where the spatial resolution doesn't match the sensor ground sample distance? Should we keep GSD as it is, and advise data providers to avoid including the gsd property in cases where it may confuse users? Or should it always be included, and we more clearly describe the properties that should be set or searched for when looking to find the spatial resolution of raster data?
The Ground Sample Distance (gsd) in common metadata states that:
In practice, I believe the value of
gsdhas come from its indication of the spatial resolution of rasters, and that folks have come to expect the gsd and spatial resolution values to match up. For example, see the discussion on this stactools PR - https://github.com/stac-utils/stactools/pull/88#issuecomment-816921490I think the case where raster data spatial resolution does not match the sensor resolution (e.g. in the case of the Sentinel 2 band downsampling, as discussed in that PR) will be confusing to users, and may deserve a rethink of how we want GSD to be defined.
I see how users are utilizing GSD as an indication of spatial resolution; are there use cases where asset GSD is being used effectively where the spatial resolution doesn't match the sensor ground sample distance? Should we keep GSD as it is, and advise data providers to avoid including the gsd property in cases where it may confuse users? Or should it always be included, and we more clearly describe the properties that should be set or searched for when looking to find the spatial resolution of raster data?