# OpenSeaMap Seamark Sector Light values

 0 Question: I extracted the OSM XML node for a light house with sector lights to use for some graphics. However, the sector values do not make sense to me. I found the attributes mentioned on several wiki pages: but none of these seems to specify the units or interpretation of the values. The first example on https://wiki.openstreetmap.org/wiki/Seamarks/Sectored_and_Directional_Lights clearly shows the first sector directed to the north-east, while its values are: ``````seamark:light:1:sector_end=260 seamark:light:1:sector_start=230 `````` Solution: The values are the heading in degrees, from a vessel. I was looking for the opposite angle... Here's a Python snippet to convert the angles (you may be able to run this on an "online Python" service): ``````#!python3 #coding=utf-8 """ Invert OSM seamark sector headings (degrees as seen from light)""" import sys,re toggle = False with open("OSM_node.xml") as f: for line in f: if "sector" in line: # get heading angle mo = re.search("'(\d+.\d)'", line) heading = float( mo.groups()[0] ) # "invert" angle angle = heading - 180 if angle < 0: angle = angle + 360 # optional: flip angles > 180 degrees (for SolveSpace CAD) if angle > 180: angle = (angle - 360) # print value and add a blank line every other print( angle ) if toggle: print() toggle = not toggle # EOF `````` PS / OT: You are welcome to start submitting your question anonymously. After submiting your question, you will be redirected to the login/signup page. Your question will > be saved in the current session and will be published after you login with your existing account, or signup for a new account and validate your email. is misleading (cannot submit anonymously) and did not work for me / question lost after registration. This question is marked "community wiki". asked 10 Sep '18, 09:59 whyohwhyohwhy 11●1●1●2 accept rate: 0%
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question asked: 10 Sep '18, 09:59

question was seen: 47,079 times

last updated: 10 Sep '18, 09:59