VIA Technologies EPIA SN-Series Specifications download pdf (Page 55)

FASTER Planning Software

With the toolbar buttons, over the graphical window, is possible to draw paths or

polygon over the Earth surface, carry out measurements, add images or placemarks for

specific locations. Placemarks and polygons can be exported in the KML/KMZ format.

5.3.1 KML/KMZ Exchange Format

KML stands for Keyhole Markup Language, is an XML-based language schema for

expressing geographic annotation and visualization on geographical browser and is an

international standard of the Open Geospatial Consortium.

The KML file specifies a set of features (placemark, images, polygons, 3D models,

textual descriptions, etc) for display in Google Earth or any other 3D geobrowser

implementing the KML encoding. Each place is always described by at least two

parameters: Latitude and Longitude. Other data can make the view more specific, such as

tilt, heading and altitude. KML files are very often distributed in the KMZ format, which

are compressed (ZIP) files with a .kmz extension. For its reference system, KML uses 3D

geographical coordinates in this order: Longitude, Latitude and Altitude. These

components are defined by the WGS84 (World Geodetic System of 1984) while the

vertical component is measured from the WGS84 EGM96 Geoid vertical datum [Ref

(25)]. Altitude can be omitted from the coordinate string, in this case the default value of

0 (approximately sea level) is assumed for the altitude component.

5.3.2 Reading KML/KMZ in Matlab

In Section 5.2 it has been pointed out that the capability of Google Earth to draw

placemark and polygons is the function that enables data exchange between different

environments. Every object drawn can be exported in an exchange format and being

known the KML file structure (see previous section) it has been possible to create a

Matlab script able to open and read KML or KMZ files.

The “read_kml.m” Matlab script directly opens KML files and searches for the

<coordinates> tag that specifies the geographical coordinates for every fix point. Values

are read and stored into a Matlab array, until the </coordinates> tag is found, and can be

successively processed by the FASTER_planner.m script.

Placemarks are individual entity inside the KML file so the Matlab script will found a

<coordinates> tags for each fix point; thus they are read as single 3 dimensional vectors

and their linear interpolation defines target area boundaries. Otherwise polygons are

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VIA Technologies EPIA SN-Series Specifications Page 55