Geospatial PDF is a set of geospatial extensions to the Portable Document Format (PDF) 1.7 specification to include information that relates a region in the document page to a region in physical space — called georeferencing. A geospatial PDF can contain geometry such as points, lines, and polygons. These, for example, could represent building locations, road networks and city boundaries, respectively. The georeferencing metadata for geospatial PDF is most commonly encoded in one of two ways: the OGC best practice; and as Adobe's proposed geospatial extensions to ISO 32000. The specifications also allow geometry to have attributes, such as a name or identifying type.
Contents
ISO 32000-2 (PDF 2.0), currently under development, will incorporate geospatial PDF features.
Overview
The popularity of geographic information systems (GIS) and geospatial technology amongst its users has increased the need to share information. However, an obstacle to sharing geospatial data can sometimes be the large file sizes or that the end recipient does not have the appropriate software or reader. The PDF format is widely accepted and is considered the de facto standard for printable documents on the web. This means that users do not require the any proprietary plug-in to read geospatial PDFs created following the PDF 1.7 specification, which was published as ISO 32000-1 standard. In this vein, some features commonly associated with geospatial PDF are simply features of PDF:
Naming
The geospatial PDF described here should not be confused with GeoPDF, a trademark used to brand geospatial PDF files created by TerraGo software.
Adobe Systems developed and maintains an open specification for use by developers to create conforming readers and writers so that there is interoperability among Adobe and other software products.
There are no restrictions for using either the OGC best practice or Adobe's proposed geospatial extensions to ISO 32000 to create applications which consume or produce geospatial PDF files. Adobe Acrobat and Reader support consumption of both of these georeferencing encodings. Adobe-specified geospatial PDF files and Terrago GeoPDF files although similar in principal are not the same thing and are not created in the same manner.
TerraGo pioneered the georeferencing of PDF files with their GeoPDF-branded map and imagery products produced from their software applications, although a TerraGo GeoPDF and a geospatial PDF are not entirely the same thing. GeoPDF products originally used the OGC best practice to encode the georeferencing metadata, but after the release of the Adobe extensions may contain either the Adobe or OGC encodings.
Uses
There are many uses for a geospatial PDF. After importing geospatial data into PDF, one can use the data in a variety of ways:
Support
There are several software developers that adhere to the PDF 1.7 specification for writing geospatial PDF files: