# MVT Mapbox Vector Tile PMTiles Google MVT Projection and Tilelive Encoding Auditor

Audit .mvt/.pbf vector tiles and PMTiles v3 archives against the Mapbox Vector Tile Specification 2.x: protobuf Layer/Feature/Value decoding, MoveTo/LineTo/ClosePath command-stream validation, ring winding and tag indexes, Web Mercator Google-tile XYZ bounds, PMTiles v3 directory decoding and tile-size vs feature-count budgets.

> Canonical page: https://elysiatools.com/en/tools/mvt-mapbox-vector-tile-pmtiles-google-mvt-projection-and-tilelive-encoding-auditor

- **Category:** Geography

- **Keywords:** mapbox vector tile, mvt auditor, pmtiles inspector, vector tile spec, web mercator tile bounds, hilbert tileid, tilelive encoding budget, protobuf geometry decoding

## Overview

Pure-TypeScript wire-format audit: a hand-rolled protobuf reader decodes Tile.layers → Layer(version/name/features/keys/values/extent) → Feature(tags/type/geometry) → Value (string/float/double/int/uint/sint-zigzag/bool). The geometry interpreter follows spec §4.3 exactly — CommandInteger = id | count<<3, zigzag ParameterIntegers, dX/dY ≠ (0,0), ClosePath count 1 polygons only, POINT = single MoveTo, LINESTRING = MoveTo+LineTo repetitions — and classifies each ring via the surveyor’s formula so exterior rings must have positive (visually clockwise, y-down) and interior rings negative area. Tile-size vs feature-count budgets follow tilelive/tippecanoe practice (≈500 KB and ≈10 000 features per tile as review thresholds). PMTiles v3 is decoded per the spec: 127-byte header, gzip/brotli internal compression, varint directories with delta TileIDs on the Hilbert curve, run-length tile entries and run-length 0 leaf pointers, cluster and conformance checks, plus tile extraction at a given z/x/y. The Web Mercator panel validates the Google tile scheme XYZ (0 ≤ x,y < 2^z) and computes the geographic tile bbox and resolution.

## Inputs

- **Tile file** (file): Upload .mvt / .pbf / .pmtiles
- **Tile zoom (z)** (number): e.g. 10 — enables the Web Mercator bbox and PMTiles lookup
- **Tile column (x)** (number): e.g. 512
- **Tile row (y)** (number): e.g. 384

## When to use

- Debugging rendering artifacts or geometry corruption caused by invalid command streams, zigzag integers, or reversed ring winding.
- Inspecting PMTiles v3 headers, directory structures, and metadata while extracting individual vector tiles by Hilbert TileID.
- Auditing tile production pipelines to flag tiles that breach standard size (500 KB) or feature-count (10,000) performance thresholds.

## How it works

- Upload an uncompressed or gzip-compressed .mvt/.pbf tile file or a .pmtiles v3 archive.
- Optionally specify the tile zoom (z), column (x), and row (y) to calculate Web Mercator bounding boxes or locate a specific tile within a PMTiles archive.
- The decoder parses protobuf layers, resolves key/value tables, verifies command integers, and computes polygon ring areas using the surveyor's formula.
- Review the structured HTML report detailing layer schemas, feature attributes, geometry command sequences, and conformance warnings.

## Use cases

- GIS pipeline engineers validating custom tile generator output against the Mapbox Vector Tile 2.x specification.
- Frontend mapping developers diagnosing missing fill holes or clipped lines in Mapbox GL JS, MapLibre, or OpenLayers.
- Cartographers and data engineers auditing PMTiles v3 metadata and root/leaf directory structures before deploying to cloud storage.

## Frequently asked questions

### What file formats does this auditor support?

It accepts single vector tile files (.mvt, .pbf), gzip-compressed tiles (.gz), and PMTiles v3 container archives (.pmtiles).

### How does the tool determine polygon ring winding order?

It applies the surveyor's formula to the decoded screen coordinates (y-down), requiring positive area for exterior rings and negative area for interior rings.

### What tile encoding thresholds trigger a budget warning?

Tiles exceeding approximately 500 KB in compressed size or containing more than 10,000 features are flagged for review.

### Are z, x, and y tile coordinates required?

No, but providing z/x/y coordinates is required to extract a specific tile from a PMTiles archive and calculate its geographic bounding box.

### Does this tool execute in the browser or send data to a server?

All Protocol Buffer decoding, PMTiles directory parsing, and geometry validation execute locally in client-side TypeScript.

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## Samples

- [MVT / PMTiles Samples](https://elysiatools.com/en/samples/mvt-pmtiles-samples): Vector tile fixtures for the Mapbox Vector Tile and PMTiles auditor
- [Hex/Unicode Encoding Format Samples](https://elysiatools.com/en/samples/text-hex-unicode-formats): Examples of hex (\xXX) and unicode (\uXXXX) escape sequence encoding formats
- [Web File Operations Go Samples](https://elysiatools.com/en/samples/web-file-operations-go): Web Go file operations examples including text file read/write, file copy/move, directory traversal, and file validation
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