Metadata Generator

What Is GIS Metadata?

Metadata is data about data. For a GIS layer, metadata describes what the layer contains, where it came from, when it was created, what coordinate reference system it uses, what the bounding box is, what the field names mean, and how the data should be interpreted. Without metadata, even the best dataset becomes a mystery six months later. The Metadata Generator on gis.tools is a free, browser-based tool that scans a GIS layer and produces a structured metadata report — including bounding box, feature count, geometry types, field names with their data types, value ranges, null counts, and other key statistics — ready to ship alongside the data itself.

Metadata is the difference between a reusable dataset and a confusing pile of files. Government data portals, academic repositories, and corporate data lakes all require metadata for cataloguing. Generating it by hand is tedious; automating it from the data itself is much more reliable.

What the Generator Reports

The Metadata Generator scans your input file and reports:

• File information — Format, size, encoding
• Spatial extent — Bounding box in the source CRS and in WGS84
• Coordinate Reference System — EPSG code, projection name, datum, units
• Feature count — Total features and a breakdown by geometry type
• Vertex count — Total vertices and average per feature
• Schema — Field names, types, and null counts
• Per-field statistics — Min, max, mean, distinct count for numeric fields; top values and length distribution for strings
• Date ranges — For any date-typed fields
• Topology summary — Whether geometries are valid; counts of any invalid features
• Hash — A content hash for integrity verification

The output can be exported as JSON, Markdown, or HTML.

How the Generator Works

The tool parses your file, walks every feature once, and accumulates statistics into a metadata document. For numeric fields, it tracks running min, max, sum, sum-of-squares (for mean and standard deviation), and a HyperLogLog sketch for distinct counts. For string fields, it samples top values. For dates, it tracks the min and max. The result is a single-pass O(n) operation that scales to millions of features.

Schema Inference

For formats without an explicit schema (like CSV without type hints), the generator infers types from the values: integers, floats, dates, booleans, or strings. Mixed types fall back to string.

Encoding Detection

For files with non-ASCII attributes, the generator reports the detected encoding so consumers know how to read the data.

Practical Applications

Data Catalog Submission

Government open-data portals (CKAN, Socrata, ArcGIS Hub) require metadata for every dataset they host. The generator produces the core fields automatically.

Data Quality Audit

Null counts, value ranges, and topology checks reveal data quality issues that need cleaning before publication.

Documentation

A Markdown metadata report can be dropped straight into a GitHub README, a data dictionary, or a project wiki.

Reproducible Research

Academic papers using GIS data benefit from publishing metadata alongside the layers, so reviewers can verify the data matches the description.

Inventory Management

A team managing dozens of layers across many projects needs a consistent way to document each one. The generator standardises the output format.

Lineage Tracking

Including the source file's hash and creation date in the metadata helps track the lineage of derived datasets.

ISO 19115 Compliance

For formal metadata standards like ISO 19115, the generator produces the core elements that hand-coding would otherwise require.

Step-by-Step Workflow in gis.tools

1. Open the Metadata Generator page.
2. Drag your GIS file into the drop zone.
3. The tool parses the file and computes statistics in a single pass.
4. Review the metadata report on the page.
5. Edit any fields manually if needed (e.g., adding a description or contact email).
6. Choose an output format: JSON, Markdown, or HTML.
7. Click Download to save the metadata document.

Worked Example

An analyst preparing a parcels dataset for a city open-data portal drops the shapefile into the generator. Within seconds, the report appears: 12,450 features, all polygons; bounding box covering the city; CRS EPSG:2236 (NAD83 / Florida East ftUS); 28 attribute fields including OWNER_NAME (string, 0 nulls, 11,200 distinct values), ASSESSED_VALUE (float, range 12,000–8,400,000, mean 285,000), YEAR_BUILT (integer, range 1894–2024, 320 nulls), and ZONING (string, 17 distinct values, top value RES-1). The analyst adds a description, a contact email, and a usage licence to the manual fields, exports as JSON, and submits the file to the portal's metadata API.

Common Pitfalls and Gotchas

• Mixed-type columns — A column that contains both numbers and strings will be reported as a string, hiding the numeric subset.
• Null vs empty string — Different formats represent missing values differently; the generator normalises to a single null count but reports the original.
• Unicode in field names — Non-ASCII field names may not survive export to certain catalog formats.
• Outdated bounding boxes — A file with stale embedded metadata may have a bbox that doesn't match the actual geometry; the generator reports both.
• Sample size for distinct counts — HyperLogLog approximations are accurate to ~2% but not exact.
• Date detection ambiguity — A column of strings like 2024-04-07 may or may not be intended as dates; the generator reports both interpretations.
• Topology errors — Self-intersecting polygons are reported but not fixed.

Tips for Best Results

• Always add a human-written description to the auto-generated metadata — statistics alone don't tell the whole story.
• Include a contact email so users can ask questions about the data.
• Document the licence and usage terms.
• Use the GeoJSON Validator & Fixer before generating metadata to flag topology issues.
• Pair with the Data Profiling Report for deeper attribute analysis.
• Include the data's source URL or DOI in the metadata.
• Hash the file and store the hash in the metadata for integrity verification.

Comparison with Other GIS Approaches

GDAL's ogrinfo -al command produces basic metadata for any vector format. QGIS displays metadata in the layer properties dialog and can export ISO 19115. ArcGIS Pro has comprehensive metadata editing tools targeted at federal compliance. The browser-based gis.tools generator occupies the niche where you want fast, automated metadata for everyday use without learning a metadata standard.

Performance Considerations

Metadata generation is O(n) on feature count and very fast — a million features take a few seconds on a desktop browser. Memory use is bounded by the running statistics, not the feature count, so even huge files work as long as they fit in browser memory.

Data Privacy and Browser-Based Processing

Metadata generation runs entirely in your browser tab. Your data is not uploaded; the generated metadata is downloaded directly to your machine. This is essential when the data itself is sensitive — patient records, infrastructure asset inventories, classified surveys.

Related GIS Concepts

ISO 19115 — The international standard for geographic metadata, defining hundreds of optional fields covering identification, quality, distribution, and lineage.

Dublin Core — A simpler general-purpose metadata standard often used as a fallback.

FGDC CSDGM — The US Federal Geographic Data Committee's content standard, predecessor to ISO 19115.

STAC (SpatioTemporal Asset Catalog) — A modern JSON-based standard for cataloguing spatial assets, especially imagery.

Frequently Asked Questions

Is the output ISO 19115 compliant?

The core fields are. Full ISO 19115 conformance requires hand-editing additional metadata elements that no automated tool can infer.

Can I generate metadata for multiple files at once?

This tool processes one file at a time. For batch jobs, use a script.

What about lineage information?

Lineage requires human knowledge about how the data was created. The generator captures the file's content but can't infer its history.

Can I edit the generated metadata?

Yes — the report has editable fields for description, contact, licence, and other manual elements.

Related Tools on gis.tools

• GeoJSON, KML, Shapefile & GIS File Viewer
• GeoJSON Validator & Fixer
• CRS Metadata Inspector
• Data Profiling Report
• Column Statistics
• Attribute Table Exporter
• Layer Packaging Tool
• Coordinate Precision Reducer