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Communicating with Geospatial PDF’s

Mark Alonzo

A challenge often face by users of geospatial imagery is the ability to easily provide information from image analysis to those who don’t have access to the same software and tools. PDF (portable document format) are currently used as a common delivery mechanism for map and satellite imagery products but lack some features necessary to understand the image analysis results. The new PDF 2.0 includes a geospatial capability; the Geospatial PDF will allow users to easily share their image analysis products and results.

A Geospatial PDF is a great way to disseminate a Common Operating Picture (COP). A COP can be a useful tool when a group of people need a common view of a region of interest – monitoring an area after a natural disaster, for example. PDFs can include many layers of raster (image) and vector (lines, shapes, and symbols) data as well as text and annotations. A GeoPDF can include raster and vector data that has been geo-referenced, where information in the file is relative to specific locations on the earth.  If there are raster layers that show images of an area on the earth and vector layers that show roads in that same area, they will all line up neatly in a GeoPDF.

Using a file with both image and vector information allows responders in a disaster area to have a quick reference that shows roads and landmarks from the vector data with the terrain and buildings in the image data. This gives many responders a Common Operating Picture that is small and portable; it can be emailed, printed, or faxed for distribution. Some PDF readers, like Adobe Reader versions 9 and above, implement the Geospatial Location Tool which identifies the location on the earth for any point in the image. With the Geospatial Location Tool and others, you can find a point or measure the distance between points.

The GeoPDF example above contains four layers: a low resolution raster image, saved as the base layer helps decrease file size but is fine for screen display, and three separate SVG (Scalable Vector Graphics) layers show landmarks, landmark names, and roads. By moving a mouse over the image, any location can be identified by its latitude and longitude, this information could then be used to visit the physical location. Overall, a Geospatial PDF is a great way to get thousands of words into one image and into the hands that need it most, quickly, and without the need for specialized software.  How do you foresee technology like the Geospatial PDF impacting the response to natural disasters?

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