There are two possible formats for storing geographic information within a PDF file. One of these formats is called GeoPDF, and it was created in early 2000’s by a company called Layton Graphics Inc. A few years later Adobe Inc released an equivalent format called Adobe Geospatial Features, which has become the default6standard.
All the geographic information either on GeoPDF or Adobe Geospatial Features is always associated to a page or an image. The geographic information allows PDF reader applications to provide calculation of coordinates of a specific point, distance between two points, or area and perimeter of a defined polygon. In order to improve the user experience while using maps inside PDF files, developers frequently use other general purpose features in the PDF specification, like layers, polygons drawing and structured data trees.
Layers allow users to hide or show specific parts or features of a map. Polygons help on representing limits, streets, terrain etc; and Structured PDF allows user selection of specific objects within a map. It also allows adding customized information to those objects in the form of Variable Name = Text Value.
The “structure tree” of a PDF file can be defined by adding specific Tags to PDF objects. PDF reader applications can identify these tags and allow users to select those objects either by clicking directly over them or by selecting them on a tree structure that the PDF reader application may show. A Tagged Object could be a polygon, a circle, a text field, etc.
Amyuni PDF Converter currently supports layers, drawings, structured data trees, and Adobe Geospatial Features. For layer’s support, developers can refer to Amyuni PDF Converter Online Documentation. Creating structured data trees (also known as marked content) and Adobe Geospatial Features with Amyuni PDF Converter will be covered in this document.