VIA Technologies EPIA SN-Series Specifications download pdf (Page 58)

FASTER Planning Software

DEM_extraction.m which searches inside the ASTER DEM database and

extracts the selected area altimetry data from a compressed archive;

 KML_export.m, produces a planned trajectory KML file.

Once imported inside Matlab, the array corresponding to the area defined in Google

Earth maintains the same reference system used by the KML standard, and geographical

coordinates are still used. In geographical coordinate system the distance covered by a

degree of longitude differs moving towards the poles and only equals the distance

covered by a degree of latitude only at the equator. Although longitude and latitude can

locate exact positions on the surface of the globe, they are not uniform units of measure.

For measurement and trajectory planning purposes a more adequate mapping solution

of the Earth surface must be adopted. A suitable map representation is the UTM

(Universal Transverse Mercator) coordinate system which is a grid-based method of

specifying locations on the Earth surface that is a practical application of a 2-dimensional

Cartesian coordinate system.

5.4.1 Universal Transverse Mercator Coordinate System

The UTM is the ellipsoidal Transverse Mercator, which is a modified Transverse

Mercator projection which, in general, has the following characteristics [Ref (26)]:

 It is a Cylindrical (transverse), conformal

projection;

 Central meridian (each meridian 90° from central meridian) and Equator are

straight lines;

 Other meridians and parallels are complex curve

 Scale is true along central meridian, or along two straight lines equidistant

from and parallel to central meridian (in case of the ellipsoidal Transverse

Mercator lines are almost straight)

 Scale becomes infinite on sphere 90° from central meridian.

The Earth, between latitudes 84°N and 80°S, is divided into 60 zones, each generally 6°

wide in longitude. Zones are numbered from 1 to 60 proceeding east from the 180

meridian from Greenwich with minor exceptions. There are letter designations from south

to north (see Figure 40) and each of these quadrangles is further subdivided into grid

squares 10

m on a side with double letter designations, including partial squares at the

grid boundaries.

Conformal map projections preserve angles locally

1 2 ... 53 54 55 56 57 58 59 60 61 62 63 ... 143 144

No comments

VIA Technologies EPIA SN-Series Specifications Page 58