Tunnel Extrapolation

From Navit's Wiki
Revision as of 13:31, 23 June 2011 by Antenna (talk | contribs) (Created page with '=== tunnel extrapolation === Tunnel extrapolation is an extrapolation function which calculates with the last available speed information before the loss of the gps signal if a ...')
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

tunnel extrapolation

Tunnel extrapolation is an extrapolation function which calculates with the last available speed information before the loss of the gps signal if a tunnel flag is set within your openstreetmaps map.

how to use

To use tunnel extrapolation you need to patch osm.c with the follow content:

Just save this patch as osm.diff, go the the navit folder, enter "patch -p0 < osm.diff" and compile navit svn. If you have already added a different patch to osm.c ( e.g. tryagain's ticket #859), the lines are probably relocated. Change the patch's line information or just copy those three lines at the right place.

Index: osm.c
===================================================================
--- osm.c       (Revision 4536)
+++ osm.c       (Arbeitskopie)
@@ -1019,6 +1019,9 @@
               flags[access_value(v)] |= AF_DANGEROUS_GOODS;
              level=5;
 }
+       if (! strcmp(k,"tunnel") && !strcmp(v,"1")) {
+               flags[0] |= AF_UNDERGROUND;
+       }
     if (! strcmp(k,"note"))
 level=5;
 if (! strcmp(k,"name")) {


Also, you need to add "tunnel_extrapolation="12" to <tracking ...>. You may need to lower this value, if the cursor runs ahead your position or vice versa, if it lags behind you. 12 stands for 1.2s extrapolation per gps rate.

Note, that this will only work if you processed your own maps with maptool and the tunnel is marked as one in openstreetmap yet (it's not? Well, go ahead!)! This article is going to help you to get your own map: http://wiki.navit-project.org/index.php/OpenStreetMap#From_.bz2


This feature will be added to svn if it has been tested with success.