Google Earth implementation has brought in new dimension for visualization. This created the opportunity for surveyors to present their data in Geographic Coordinate Systems. Mostly, surveyors display their information for clients with maps and two-dimensional graphics (Cartesian Coordinate System), either on paper or digitally. With Google Earth there is a way to represent two-dimensional drawings to be shown in three dimensions, with an understandable backdrop of Earth Image. This has enabled surveyors a greater opportunity to impress clients and make it more understandable.
With simply powerful interface Google Earth combines and displays stunning graphics and a planet full of data to which anyone may add information and share that information with the rest of the world in just a few short clicks. In a very short time Google Earth became very popular (More then 1 billion download) Because of its simplicity and power. It is simple to use yet highly stable.
Survey Drawings use Cartesian co ordinate System to represent point. Google earth on the other hand Uses WGS84 Map datum to represent data. To make survey drawings compatible with Google Earth a geodetic transformation is required.
In this article I have explained how one can Easily convert their Survey drawings in to KML File that can be opened with Google Earth. With release of ESurvey KML it has become very easy to convert any Survey Drawing (Road, Railway, Irrigation, Canal, Layout, City Map) to a KML file that can be Opened with Google Earth Geo browser. When you can see your survey drawing in relation to Imagery and terrain, it becomes very easy to check quality of data that has been captured.
To understand Converting Drawing to KML you just need to Understand couple of Commands in ESurvey KML. But if you are interested to know in detail how that is really happening, you need to understand many terms Clearly.
|1||Cartesian coordinate system (CCS)||9||Ellipsoid|
|2||Geographic Coordinate Systems||10||Map|
|3||Geographic Directions||11||Map Datum|
|5||Meridian||13||Universal Transverse Mercator coordinate system|
|6||Prime Meridian||14||UTM Zone|
|8||Geodetic Height||16||KML File|
Further I have explained about Google Earth in Brief. Once you understand these then converting CAD Drawing to Google Earth or Converting Way points marked in Google Earth as a CAD File will be very Simple.
Google Earth is a free computer program, it uses a virtual globe to map the Earth using superimposed satellite and aerial imagery. Google Earth Uses WGS84 Coordinate System to represent the whole world. It is a free application any can be installed on any computer.
Google Earth works by connecting to the Internet to stream data to the users. You can pan, zoom, tilt (for 3D perspective) virutal globe with in Google Earth and navigate to any point with Simple interface given.
Google Earth can open a Documents called Keyhole Markup Language (KML) documents and overlay the content on available imagery. KML is a simple text-formatted syntax that provides basic information regarding location, data type (points, lines, polygons), symbology, and attributes.
KML and KMZ:
Since KML file is a simple text file. Normally it will take more disk space (bytes) and hence google also allows to open compressed KML files directly. Comparessed format of the KML need have the Extension KMZ. So there is no difference between KML and KMZ File except that KMZ is compressed version of KML File.
Google earth also allows to mark points, lines, polygons with in Google earth interface. Once you mark such points in area of your interest then such data can be stored as KML/KMZ File. ESurvey KML can convert these KML and KMZ files in to CAD Drawing (DXF).
Also Since CAD data will be in Cartesian coordinate system, ESurvey KML can convert this data into KML files which can be further opened in Google Earth.
To learn more about Google Earth – Navigation, Steps involved in Saving Google earth file as KML Etc.
Please visit to the google earth page. To download ESurvey KML Please visit to the esurveying download page.