How do you get accurate elevation from google earth ?

Hey guys
How do you get accurate elevation from google earth ?
It seems like the elevations in google earth are not accurate.
When following google earths elevation info on bottom right roads just seem incredibly steep.
I usually get the elevation i want by zooming in to road junction and just getting the elevation from the bottom right of the screen.


Would anyone know a way to get a more accurate elevation..
Can it be obtained in the map co-ordinates ? using latitude and longitude ?

Thanx

Bridges, gullies, cuts, fills, trees and buildings, ... etc ... can throw off the elevations, so you need to get into a clear spot ... I did notice that GE shows a difference of heights, as opposed to that Transdem, of @ +3m

I'm not sure how the x,y coordinates will work any better. You are using the application, right?

The measurements are quite accurate, but it's only as good as the original measurements taken from the satellite source. They use the same DEM information we download into TransDEM for the regions. Compared to TransDEM information, the elevation is close and in some cases spot on. The issue has to do with a bunch of things as I said the source, date and resolution.

1) We have satellites picking the data off the earth and depending upon how old the data is, the methodology has changed for the better. Earlier we had lower resolution data capture and also more object interference. As the data and technology has gotten better, this has become less of an issue.

On a route I have worked on in the past, I modeled my own area. The railway line is up on a grade about 4 meters above the landscape and crosses River Street and then the Merrimack River. This raised grade, when looking from above and facing north, is up against a 326 meter hill (Silver Hill), and up against some old shoe factories on the right. With the lower resolution DEM, the rail ROW mushes right down to a blob and then completely disappears as a continuous slope. The station area and River Street complete disappear, and the old mill buildings are a mush blob. This took quite sometime to sort out and the results were poor.

2) We deal with fixed increments based on a 5 or 10 meter grid-steps while the satellite is many, many increments.

When we bring in DEM data into Trainz, that much smoother terrain with the higher-resolution imaging gets transcribed to multiple-steps. To mitigate this issue, use much higher resolution DEMs and a 5 meter grid.

I've been involved in a project with a fellow Trainzer whose working on a route in the Deerfield and Hoosac River valleys and the surrounding area which includes the famous 4.75 mile Hoosac Tunnel. Using 1/3 arc-second resolution, available for the area, plus a 5-meter grid where needed, the height differences between what I measured in Google Earth compared to what came through TransDEM was only a few meters. The only places where it was not accurate was where the rail grade sunk downward towards the West Portal tunnel entrance. What I did for that is interpolate a smoother grade for the railway line, because when taken literally the grade was something like 6% and I know that isn't correct.