Reference Formats
KMZ
KMZ is a compressed, zipped archive that bundles a KML file together with any images, icons, and 3D models it references, into one shareable package.
Extension
.kmz
Full name
Zipped Keyhole Markup Language
Introduced
Introduced alongside KML by Keyhole, Inc. in the early 2000s as the compressed distribution format for Google Earth content
Vendor
Keyhole, Inc. (acquired by Google in 2004); the KML format it wraps is OGC-standardized
What is inside the container
A KMZ file is a ZIP archive that, by convention, contains one KML file named doc.kml at its root alongside an images or files folder holding the icons, ground-overlay textures, and 3D models the KML references. Unzipping a KMZ produces a valid standalone KML plus its assets, so KMZ is best understood as KML's packaging solution to the exact companion-file problem that plain KML (and, differently, Shapefile) is prone to.
How to open it
For archives
Prefer KMZ over bare KML for DAM archiving whenever the map includes overlay images, custom icons, or 3D models, since the zip packaging guarantees the KML and its assets stay together as one file through upload, versioning, and download. Keep the original KMZ intact rather than re-zipping it, and extract the internal doc.kml only for metadata indexing or preview rendering.
KMZ was introduced by Keyhole, Inc. alongside KML itself, as a compressed packaging format for distributing Google Earth content that includes more than plain placemark geometry — image overlays, custom icons, and 3D models. Following Google’s 2004 acquisition of Keyhole, KMZ became the standard way Google Earth content with embedded media is shared and downloaded.
A KMZ file is, mechanically, just a ZIP archive: open one with any unzip utility and, by convention, you’ll find a doc.kml file at the root plus a folder of the images, icons, and models that KML file references. That’s the entire trick of the format — instead of leaving those referenced assets as external files the way plain KML does, KMZ folds them into the same container so the map and its media can never be separated in transit.
- doc.kml — the placemark, path, and style markup, conventionally at the archive root
- images/ or files/ folder — ground-overlay textures and custom icon images
- 3D models — referenced model files used by some placemarks
For a DAM, KMZ is the more asset-management-friendly of the two Keyhole formats precisely because it solves the multi-file problem that plagues Shapefile and, in a milder way, image-referencing KML: one file in, one file out, with everything the map needs already inside it. A DAM can treat a KMZ exactly like any other single-file binary asset for storage and versioning, while still being able to peek inside the zip to extract the doc.kml for metadata indexing, geographic extent, and thumbnail generation.
This is also a useful pattern to point to when explaining to non-GIS users why some geospatial formats are painless in a DAM and others aren’t: KMZ and GeoPackage both solve the companion-file problem by containerizing everything into one file, while Shapefile solves nothing and simply expects the user to keep several files together by discipline.
Frequently asked
What's actually inside a KMZ file?
A ZIP archive containing, by convention, a doc.kml file at the root plus a folder of the images, icons, and 3D models that the KML references.
Can I just unzip a KMZ to get the KML back?
Yes, any standard unzip tool extracts a valid KML file plus its referenced assets, since KMZ is a ZIP archive with a renamed extension.
Why would a DAM prefer KMZ over plain KML?
KMZ bundles the KML with every image, icon, and model it depends on into one file, so the asset can't lose its supporting media the way a bare KML with external references can.
Does compressing a KML into KMZ lose any data?
No, ZIP compression used for KMZ is lossless, so the KML markup and embedded assets are preserved exactly.
Can Google Earth and QGIS both open KMZ files?
Yes, Google Earth Pro opens KMZ natively, and QGIS reads it through its OGR-based vector data provider, unpacking the archive to read the KML inside.
Is KMZ good for storing 3D models and image overlays in a DAM?
Yes, that's exactly the use case it was built for — bundling ground-overlay imagery and 3D model references together with the placemark geometry that positions them.
How should a DAM generate a preview thumbnail for a KMZ asset?
By unzipping the archive, reading the internal doc.kml for the geometry and camera view, and rendering that with a tool like QGIS or a KML-aware library rather than trying to preview the zip file directly.
Can KMZ be converted to GeoJSON or GeoPackage?
Yes, GDAL/OGR's ogr2ogr reads KMZ the same way it reads plain KML and can convert it to GeoJSON, GeoPackage, or Shapefile.
Sources
- KMZ is a zipped KML plus referenced images, icons, and 3D models, developed by Keyhole Inc. checked 2026-08-07 — General KML/KMZ format references (Google Earth documentation ecosystem)
- Keyhole, Inc. acquired by Google in 2004; KMZ became the standard shareable Google Earth package format checked 2026-08-07 — OGC KML standard page