Hi thanks for looking How accurate is Google overlay? I used 1 arc elevation data instead of 2 arc. Layed some track following the track on Google overlay and I can see parts of the railway embankment a bit to left of where my tracks are layed. Is this a bug or just the way it is? Thanks.
Not TS specifically but I have often found DEM data at odds with mapping data, whether Google, OSM or even US Topo maps. Take both as a rough guide and eyeball it.
Older routes were built without the Google maps overlay functionality, so expect some offset and deviations in them.
Thanks for the replies. Yea I noticed on other routes that the track doesn't always follow the path of the track on Google overlay. I had a feeling the map data and dem data would not be perfect. I've always used 2 arc so railway embankments and stuff have not been visible. Using 1 arc it seems possible to follow the actual paths of tracks and use overlay just for scenery. Thanks.
Even some of the best DEM can be inaccurate particularly over forested or built up areas where the satellite "sees" the trees or tall buildings as terrain and averages the data to create hills and valleys. I went through a phase of wanting to do the Hong Kong tramway or at least a resemblance of it in Trainz. However even the 30m DEM was impossible to work with as there was so much up and down across what should have been largely level terrain in the city area at any rate.
I didn't account for forests and buildings. Now it makes sense why some of the hills are a lot more elevated than in real life. Fortunately i have not made any routes through large towns or cities yet although the route im working on at the moment ends in a big town. ill see what happens when i get there. thanks.
