From German - English Ding/FreeDict dictionary ver. 1.9-fd1:
Sichtachse /zˈɪçtaxzə/ <fem, n, sg>
line of sight <n>, sight line <n>, sight axis <n>, view axis <n>, axis of vision <n>, eyeline <n>
Synonyms: Blickachse, Blickbezug, Sicht
see: Blickachsen, Blickbezüge, Sichtachsen, Sichten