User`s guide

R14SP3
20-2
Geodetic-Geocentric Coordinate Conversion Functions
New three-dimensional coordinate conversion functions (geodetic2ecef,
ecef2geodetic, ecef2lv, lv2ecef) transform 3-D point locations between geodetic
(latitude, longitude, height), geocentric Cartesian (Earth Centered, Earth Fixed), and
local vertical Cartesian coordinate systems.
Additional User Control Over Shapefile Content
Function shapewrite now allows user control over field names, lengths, and decimal
precision when writing feature attributes to the DBF file, via a “DBF specification.” The
new function makedbfspec constructs a default DBF specification from a geographic
data structure (geostruct2) array. Users can customize the output and pass it to
shapewrite.
Shapefile Read/Write Efficiency Enhanced
Improved implementations of functions shaperead and shapewrite process data
substantially faster (about four times faster for a 10-MB shapefile of major roads in
Massachusetts).
Improved Rendering of Polygons with Inner Rings
The Map Viewer (function mapview) and functions mapshow and geoshow now properly
render polygons containing inner rings (e.g., lakes and inland seas within a continent,
islands within a pond). Features in underlying layers “show through” inner rings because
they are not obscured by the patch faces used to render the polygons.
Compatibility Considerations
Polygon Vertex Ordering Is Now Significant for Properly Rendering Filled
Polygons
The map display functions geoshow, mapshow, and mapview now require that
coordinate vectors representing polygons have consistent directionality, such that
• Vertices defining outer rings (to be filled) be encoded in a clockwise direction.
• Vertices defining inner rings (often termed “lakes” or “islands,” to be rendered as
transparent holes) be encoded in a counterclockwise direction.