DDL GHSL Built-up Zonal Statistics

Dataset: ghsl-builtup
Package scope: Released parent agglomerations and their ADM1 and ADM2 splits
Dataset version: v0.3.0

Contents
- ddl-ghsl-builtup.parquet: all observations
- This README

Schema
- id: Parent or child city identifier.
- version: Boundary version.
- boundary_level: PARENT, ADM1, or ADM2.
- ghsl_release: GHSL release used for every non-null metric in the row.
- ghsl_year: Configured GHSL raster epoch; see the Epoch coverage notes below for details.
- built_up_surface_sum_m2: Area-weighted sum of GHSL built-up surface pixels across the source boundary.
- built_up_surface_avg_m2: Area-weighted mean of GHSL built-up surface pixels across the source boundary.
- built_up_volume_sum_m3: Area-weighted sum of GHSL built-up volume pixels across the source boundary.
- built_up_volume_avg_m3: Area-weighted mean of GHSL built-up volume pixels across the source boundary.
- nonres_built_up_surface_sum_m2: Area-weighted sum of GHSL built-up surface pixels classified as non-residential across the source boundary.
- nonres_built_up_surface_avg_m2: Area-weighted mean of GHSL built-up surface pixels classified as non-residential across the source boundary.
- nonres_built_up_volume_sum_m3: Area-weighted sum of GHSL built-up volume pixels classified as non-residential across the source boundary.
- nonres_built_up_volume_avg_m3: Area-weighted mean of GHSL built-up volume pixels classified as non-residential across the source boundary.
- gross_built_up_height_avg_m: Area-weighted mean gross built-up height of GHSL built-up pixels across the source boundary
- net_built_up_height_avg_m: Area-weighted mean net built-up height of GHSL built-up pixels across the source boundary.
- built_up_surface_valid_coverage_share: Share of zone area covered by valid pixels for the corresponding metric.
- built_up_volume_valid_coverage_share: Share of zone area covered by valid pixels for the corresponding metric.
- nonres_built_up_surface_valid_coverage_share: Share of zone area covered by valid pixels for the corresponding metric.
- nonres_built_up_volume_valid_coverage_share: Share of zone area covered by valid pixels for the corresponding metric.
- gross_built_up_height_valid_coverage_share: Share of zone area covered by valid pixels for the corresponding metric.
- net_built_up_height_valid_coverage_share: Share of zone area covered by valid pixels for the corresponding metric.

Epoch coverage — read this before filtering on ghsl_year
- Epochs present in this package: 1975, 1980, 1985, 1990, 1995, 2000, 2005, 2010, 2015, 2018, 2020, 2025.
- ghsl_year is a raster epoch, NOT a regular annual or 5-yearly series.
- The metric families are not published on the same epochs. Built-up surface
  and volume (including the non-residential and per-cell average fields) are
  published on the 5-year epochs; GHS-BUILT-H — gross_built_up_height_avg_m
  and net_built_up_height_avg_m — is published for a single epoch of its own.
- So every row carries ONE family and nulls the other. Selecting a single
  latest epoch drops a whole family silently: at the newest epoch both height
  columns are null for every boundary.
- Select per metric family, not per row. Each metric's *_valid_coverage_share
  identifies the epochs where that metric is actually observed: the share is
  0 on an epoch whose raster does not exist, and null metrics stay null.

Notes
- Keep every metric with its corresponding valid-coverage share.
- Null metrics remain unavailable and must not be interpreted as zero.
- A coverage share of 0 means the raster was absent or no valid pixel fell
  inside the zone. It is not a measurement of zero built-up land.
- The per-source-cell average surface and volume fields depend on source resolution.
- Filter boundary_level before aggregating to avoid double counting parent and child zones.

License
- Released under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Disclaimer
By accepting data provided by the Development Data Lab (DDL), you agree to the following conditions of release and acknowledge the following disclaimers: Neither DDL nor the contributors of data to DDL shall be held liable for any improper or incorrect use or application of the data provided, and assume no responsibility for the use or application of the data or information derived from interpretation of the data. In no event shall DDL or its collaborators be liable for any direct, indirect, or incidental damages arising from the use or application of these data. This disclaimer of liability applies to any damages or injury, including but not limited to those caused by any failure of performance, error, omission, defect, delay in operation or transmission, computer virus, alteration, use, application, analysis, or interpretation of data. No warranty, expressed or implied, is made regarding the accuracy, adequacy, completeness, reliability, or usefulness of any data provided. These data are provided on an "as is" basis. All warranties of any kind, express or implied, including but not limited to fitness for a particular use, freedom from computer viruses, and non-infringement of proprietary rights, are disclaimed. Data are added and changed periodically, and data may become out-of-date quickly. It is recommended that the user not let a significant period of time elapse between obtaining and using the data.
