The input of spherical lines using Euler transformation and length is quite circumstantial (see Section 3.5). For short lines it is easier to input a line specifying the beginning and the end of the line.
sline( | begin, | |
end); |
spoint begin;spoint end;
If the distance between begin and
end is 180° (π), this function
returns an error because the location of the line is undefined.
However, if longitudes of begin and
end are equal,
pgSphere assumes a meridian and
returns the corresponding spherical line.
Example 4.4. A line created using begin and end of line
A line starting at spoint '(270d,10d)' and
ending at spoint '(270d,30d)':
sql> SELECT set_sphere_output('DEG')
set_sphere_output
-------------------
SET DEG
(1 row)
sql> SELECT sline( spoint '(270d,10d)', spoint '(270d,30d)');
sline
----------------------------
( 10d, 90d, 270d, ZXZ ), 20d
(1 row)
Furthermore, there is a function for inputing a line
using Euler transformation trans
and line length length
sline( | trans, | |
length); |
strans trans;float8 length;
where the line length length must be
given in radians.
Example 4.5. A line created with its transformation and length
The same line as in Example 4.4, but using transformation and line length.
sql> SELECT sline ( strans '10d, 90d, 270d, ZXZ', 20.0*pi()/180.0 );
sline
------------------------------
( 10d, 90d, 270d, ZXZ ), 20d
(1 row)