Significance of Coordinate Systems in SPCAD
Significance of Coordinate Systems in SPCAD
Coordinate Systems in SPCAD form the backbone of accurate spatial data management. By assigning the correct reference ellipsoid and projection system, users can import KML or GPX files, export raster and vector data, and perform precise parcel calculations.
Reference Ellipsoid
A reference ellipsoid, or spheroid, serves as a mathematical model to approximate the shape of the Earth. It forms by rotating an ellipse about its axis. Consequently, you can parameterize it using the lengths of the semi-major axis and semi-minor axis, along with flattening or eccentricity. Geodetic latitude and longitude appear on its surface, and surveyors then project these coordinates onto a flat surface for mapping and survey purposes.
| Name | Semi-Major Axis | Semi-Minor Axis |
|---|---|---|
| Clarke | 6,378,206.4 m | 6,356,583.8 m |
| WGS72 | 6,378,135.0 m | 6,356,750.5 m |
| WGS84 | 6,378,137.0 m | 6,356,752.3 m |
Projection System
The projection system uses mathematical models to convert the curved surface of the reference ellipsoid onto a flat plane. Depending on the purpose and geographic location, you select a specific projection for the area under consideration. Next, the system draws a grid of linear units on the plane. Finally, it adds values for false easting and false northing to the coordinates, ensuring the entire region fits within the first quadrant.
Examples of Coordinate Systems
SPCAD users encounter diverse coordinate systems, tailored to specific regions or mapping requirements. Two exemplary systems include:
- Ellipsoid: WGS84, Projection: Transverse Mercator
- Ellipsoid: Kallianpur (Everest), Projection: Lambert Conformal Conic
Benefits of “Assign Coordinate System” in SPCAD
SPCAD’s “Assign Coordinate System” tool offers several key functionalities, enhancing the software’s versatility and adaptability:
- Import Operations: Facilitates accurate import of KML and GPX files.
- Raster and Vector Export: Enables export of raster data to KMZ, KML, shapefiles, and GPX formats.
- Spatial Transformation: Supports transformation of drawings between coordinate systems.
- QR-Code Integration: Assists in the precise insertion of location-based QR codes into drawings.
- Parcel Annotation: Computes parcel area based on user-specific units.
- LOT Parcels to KML and Shapefile Formats: Facilitates export of LOT parcels to KML and shapefile formats.
Optional Usage in Other Tools
While not mandatory, utilizing a coordinate system can be advantageous in certain applications, such as:
- Data-Driven Pages and Callouts: Establishing a coordinate system enhances functionalities like data-driven pages and callouts, enabling the display of locations using geographic coordinates (i.e., latitude and longitude).
Example Application
In SPCAD, you can seamlessly convert drawings from their original Universal Transverse Mercator (UTM) or Lambert Conformal Conic (LCC) coordinate systems to KML format once you assign the correct coordinate system. As a result, this integration ensures smooth compatibility with geographic coordinate-based formats like KML, providing users with enhanced flexibility and usability when managing spatial data.
