Points visible from here (x) marked in white. Grid=230,235km W; 2670,2675 N km TWD67. Black=township lines. Sorry it's my first try with GRASS GIS. Data source: DTM files were obtained from professors I met at GIS conferences.
Further away, we can see these points. Altitude (m), azimuth (deg), and distance (km)
2300 63.40 12.2 Shaolai Shan south edge 3283 140.60 43.9 Ganzhuowan Shan 3368 146.48 46.2 Zhuosheda Shan 1064 147.68 5.5 Heitian Shan 556 152.7 25.9 Huzi Shan (center of Taiwan)* 3275 153.18 74.7 Neilinger Shan 2357 153.73 51.5 Jianianduan Shan 3255 154.08 73.9 Malubalarang Shan 3619 159.42 65.7 Dongjunda Shan 2017 159.81 38.2 Dajian Shan 3437 161.34 69.1 Zhu Shan 3483 162.65 77.5 Maliyawenlu Shan 3231 163.48 68.3 Wushuang Shan 2112 163.99 39.5 Shuishe Shan 3765 164.34 76.1 Mabolasi Shan 2058 164.55 39.1 Shuishe Shan 2483 164.65 49.3 Zhimao Shan north peak 2909 166.34 49.9 Zhimao Shan 2863 167.34 50.8 Zhimao Shan south Peak 775 171 36 Riyue Tan (Sun Moon Lake)* 3952 173.25 79.4 Yushan* 1126 186.49 5.8 Touju Shan 250 238.82 81.8 Formosa Plastics sixth plant smokestack
These points visible only if air dry. Some can only be seen once or twice a year. Snow, if any, is visible in binoculars. * = below horizon. (Shan means mountain.)
The Neilinger Shan to Malubalarang Shan ridge line is in Hualian County. Map: White: Nantou / Hualian County boundary. Green: visible areas. 3 x 3 km square: e=270 w=267 n=2611 s=2608 km TWD67
I remembered to subtract the earth's curvature from the DTMs...
Before I forget, here's how one can compute the above:
$ perl -F, -anwMMath::Trig -e'use strict;
if ( $F[0] eq q() ) {
@_ = Math::Trig::cartesian_to_spherical(
$F[3] - 235480,
$F[4] - 2675351,
$F[5] - 777
);
@_ = ( $F[5], ( shift @_ ) / 1000, map { 90 - rad2deg($_) } @_ );
printf "%d %6.2f %4.1f %.2f\n", @_[ 0, 2, 1, 3 ];
exit;
}' twntwd67v1.csv
3952 173.25 79.4 2.29
Last modified: 2007-01-29 10:22:07 +0800