GIS formats: vectors, rasters and interchange

Guide Updated 24 October 2026

Choose a GIS format around the information you must preserve and the software that must read it. Distinguish vector features, numeric rasters and rendered map images before choosing a file extension; then verify a small handoff with its attributes, coordinates and metadata intact.

Start with the object you need

Write down the intended operation. Selecting road features by an attribute needs a different kind of input from displaying a background map. Computing with terrain heights needs the elevation values and their reference information, not merely a colour image that resembles terrain.

For a vector handoff, list the geometry, the fields and the identifiers that another person must receive. For a raster, list the bands, value meanings, dimensions and missing-value convention. For a web service, identify the actual operation it supplies. The OGC Web Map Service standard describes requests for georeferenced map images; a displayed WMS layer is not, by that fact alone, a downloadable feature table or elevation grid.¹

This distinction helps when a portal offers several buttons called “download”, “export” or “open”. Follow the chosen route and read what it produces. An image export can be useful for a presentation while remaining unsuitable as the input to a feature join or a terrain calculation.

Keep a shapefile set together

A shapefile handoff is a set of related files rather than just the file ending in .shp. GDAL describes the associated .shp, .shx and .dbf files as a layer set, with other files supplying information such as coordinate reference or text encoding.² Keep the delivered set together and preserve its original naming relationships.

Before exporting, inspect long field names, identifiers with leading zeros, decimal precision and non-ASCII text. Write the expected values down. A format conversion that produces a readable layer can still change the table structure needed by the next analyst.

The round-trip observations show sixty configured observations across three specific implementations. They are useful examples of what to check, not a ranking of tools or a promise about your files. Pay special attention to the difference between stored positional values and a dictionary view: duplicate field names can make a projected key collide without proving that the underlying file value disappeared.

Treat driver versions as part of the handoff. GDAL’s current shapefile documentation describes both DBF field-name limits and newer sidecar support for names and aliases.² A blanket statement that every reader exposes exactly the same field names would miss that implementation detail. Confirm the behaviour in the actual receiving application.

Consider a container when the handoff needs one

GeoPackage uses a SQLite container with conventions for features, tile matrix sets, attributes and extensions.³ It can provide a structured handoff where your project needs several related tables or layers in one container. That does not remove the need to specify which layers matter or whether the recipient supports any extensions you use.

Choose it because those capabilities fit the task, not because a single file guarantees a complete project. Keep a short manifest naming the required layers, coordinate references, identifiers and expected record counts. Open the resulting container in the receiving software and inspect representative records before treating the transfer as finished.

If the recipient requires a simpler exchange format, document the compromises rather than silently changing fields. A shortened name can remain usable when accompanied by an explicit mapping. An identifier converted to a number can be harder to recover if leading zeros carried meaning. Agree on the schema before bulk conversion.

Read raster location and value metadata separately

A raster’s position and its values answer different questions. Position tells you where the grid lies. Band metadata and the product documentation tell you what a value represents, including units and the distinction between a measured value and missing data.

A world file contains six numeric values describing pixel size, rotation and the position of the upper-left pixel centre.⁴ Those six numbers do not constitute a coordinate-reference-system definition. Keep the corresponding reference information with the image instead of expecting the world file alone to explain the coordinate units or datum.

For elevation work, also check the vertical reference. A file that aligns horizontally with another layer may still express heights differently. Use the elevation guide to record that distinction and the download and inspection guide to run a local metadata check. Neither a screenshot nor a familiar extension establishes those properties.

Use the format route selector

The format selector gives one next step for a shapefile set, a raster, a web service or an elevation task. Select the object you actually have. The text and destination change together, and Reset restores the initial route.

Its choices are intentionally limited. It does not examine a file, detect a format from bytes or certify compatibility. Use it to reach the right checklist, then apply that checklist to the original publisher’s record and the files you obtained. If your input does not fit one of the choices, preserve it and identify the format before attempting a conversion.

For a web service, begin by distinguishing map display from data access. For a raster, inspect location and band metadata. For a shapefile set, keep the components together and inspect the schema. For elevation, add the surface description, units and vertical reference before combining anything.

Finish with a small acceptance check

Create a handoff note with the source, date, format, software version and expected contents. Include one or two representative records chosen to exercise the fields that matter: an identifier, a decimal and a non-ASCII name are more informative than three interchangeable plain strings.

Reopen the result and compare those records with the source. Check coordinates as well as attributes, and record a deliberate change separately from an unexpected one. If a field was renamed, retain the mapping. If a value cannot be represented, stop and choose an explicit alternative rather than accepting a visually plausible map as sufficient evidence.

Not covered on this page

• A universal best GIS format or a comparison of commercial conversion products.
• Database administration, service deployment, or full application compatibility testing.
• Coordinate transformations, field-specific legal advice, or a guarantee of lossless conversion.