greetings. im not shure, but i think most of us know about the Google Earth altitude data mismatch when importing to BTB. i had downloaded Hybrid Geotools ( a Google Earth plugin) to layout a track and give it altitude data when i found the problem. seems the auto-update is based on sattelite data,which is not accurate.
however, if you set a Geopoint in sattelite view, then zoom in to street view, you can manipulate the Geopoint with the arrow buttons. when the Geopoint intersects with a solid object in the image, like a road or building, it will begin to dissapear into image. if you move the Geopoint so it barely touches the image (set movement to 0.01m/click),then set the "fixed" button,the Geopoint will turn into a red circle with a "+" crosshair perfectly set on the line (horizontal if setting on the road) and give you a coordinance with 0.01m accuracy. this data isnt from the sattelite, this data comes from the Google van recording the street view and is GPS data, not sattelite.
when i layout a road in BTB, i increase the cross-section from 4 to 8 tiles wide,giving me 9 points to adjust to give the road increased texture.
in the Geotools/street view, i set 9 Geopoints across the width of the road to make a cross-section measuring tool,plus 1 more Geopoint set at the other points shaping the curves gives you a linear distance measurement.
here is an example of Geopoint data i made from a test road. i took measurements at 2.5 meter intervals.
# = cross-section number
440= center of road
441=left side of road
448=right side of road
distance to (0.84) is the width between cross-section Geopoints
alt (266.29) is the altitude above sealevel,generated by the Google van and imprinted into the image data
distance= linear distance down the road
all measurements are in meters
CROSS-SECTION - 441 - 442 - 443 - 444 - 440 - 445 - 446 - 447 - 448 -
/DISTANCE -ALT/DISTANCE TO-
# 0 /0.0 - 266.29/0.84 - 266.27/0.84 - 266.25/0.84 - 266.21/1.68 - 266.20/3.36 - 266.18/0.84 - 266.15/0.84 - 266.12/0.84 - 266.10/0.00 -
# 1 /2.50 - 266.31/0.84 - 266.29/0.84 - 266.29.0.84 - 266.27/1.68 - 266.23/3.36 - 266.24/0.84 - 266.22/0.84 - 266.20/0.84 - 266.19/0.00 -
# 2 /5.00 - 266.48/0.84 - 266.46/0.84 - 266.46/0.84 - 266.44/1.68 - 266.42/3.36 - 266.41/0.84 - 266.39/0.84 - 266.37/0.84 - 266.36/0.84 -
# 3 /7.50 - 266.53/0.84 - 266.53/0.84 - 266.51/0.84 - 266.51/1.68 - 266.49/3.36 - 266.49/0.84 - 266.47/0.84 - 266.46/0.84 - 266.45/0.84 -
# 4 /10.0 - 267.03/0.84 - 267.03/0.84 - 267.02/0.84 - 267.01/1.68 - 267.02/3.36 - 267.01/0.84 - 267.00/0.84 - 266.99/0.84 - 266.98/0.84 -
# 5 /12.5 - 267.10/0.84 - 267.10/0.84 - 267.09/0.84 - 267.08/1.68 - 267.09/3.36 - 267.07/0.84 - 267.07/0.84 - 267.06/0.84 - 267.05/0.84 -
# 6 /15.0 - 267.17/0.84 - 267.17/0.84 - 267.16/0.84 - 267.15/1.68 - 267.15/3.36 - 267.14/0.84 - 267.12/0.84 - 267.12/0.84 - 267.12/0.84 -
# 7 /17.5 - 267.22/0.84 - 267.21/0.84 - 267.22/0.84 - 267.21/1.68 - 267.18/3.36 - 267.17/0.84 - 267.15/0.84 - 267.14/0.84 - 267.14/0.84 -
# 8 /20.0 - 267.77/0.84 - 267.77/0.84 - 267.77/0.84 - 267.76/1.68 - 267.77/3.36 - 267.76/0.84 - 267.75/0.84 - 267.75/0.84 - 267.75/0.84 -
# 9 /22.5 - 267.84/0.87 - 267.83/0.87 - 267.83/0.87 - 267.81/1.74 - 267.81/3.48 - 267.81/0.87 - 267.79/0.87 - 267.79/0.87 - 267.79/0.87 -
# 10 /25.0 - 267.91/0.87 - 267.89/0.87 - 267.89/0.87 - 267.89/1.74 - 267.88/3.48 - 267.87/0.87 - 267.87/0.87 - 267.85/0.87 - 267.85/0.87 -
you can see there is alot of variation in the data.
the first 438 Geopoints were used to layout the shape of the road,disregarding altitude changes and focusing on the curves,layed out in the sattelite view.Geopoint #439 follows these points to give you an accurate straight-line measurement with #440 (the centerline Geopoint).
the altitude data is then changed manually in BTB from the 4-screen view and moving the points to the corresponding altitude from either of the 2 lower screens.
very tediouse but extremely accurate.
however, if you set a Geopoint in sattelite view, then zoom in to street view, you can manipulate the Geopoint with the arrow buttons. when the Geopoint intersects with a solid object in the image, like a road or building, it will begin to dissapear into image. if you move the Geopoint so it barely touches the image (set movement to 0.01m/click),then set the "fixed" button,the Geopoint will turn into a red circle with a "+" crosshair perfectly set on the line (horizontal if setting on the road) and give you a coordinance with 0.01m accuracy. this data isnt from the sattelite, this data comes from the Google van recording the street view and is GPS data, not sattelite.
when i layout a road in BTB, i increase the cross-section from 4 to 8 tiles wide,giving me 9 points to adjust to give the road increased texture.
in the Geotools/street view, i set 9 Geopoints across the width of the road to make a cross-section measuring tool,plus 1 more Geopoint set at the other points shaping the curves gives you a linear distance measurement.
here is an example of Geopoint data i made from a test road. i took measurements at 2.5 meter intervals.
# = cross-section number
440= center of road
441=left side of road
448=right side of road
distance to (0.84) is the width between cross-section Geopoints
alt (266.29) is the altitude above sealevel,generated by the Google van and imprinted into the image data
distance= linear distance down the road
all measurements are in meters
CROSS-SECTION - 441 - 442 - 443 - 444 - 440 - 445 - 446 - 447 - 448 -
/DISTANCE -ALT/DISTANCE TO-
# 0 /0.0 - 266.29/0.84 - 266.27/0.84 - 266.25/0.84 - 266.21/1.68 - 266.20/3.36 - 266.18/0.84 - 266.15/0.84 - 266.12/0.84 - 266.10/0.00 -
# 1 /2.50 - 266.31/0.84 - 266.29/0.84 - 266.29.0.84 - 266.27/1.68 - 266.23/3.36 - 266.24/0.84 - 266.22/0.84 - 266.20/0.84 - 266.19/0.00 -
# 2 /5.00 - 266.48/0.84 - 266.46/0.84 - 266.46/0.84 - 266.44/1.68 - 266.42/3.36 - 266.41/0.84 - 266.39/0.84 - 266.37/0.84 - 266.36/0.84 -
# 3 /7.50 - 266.53/0.84 - 266.53/0.84 - 266.51/0.84 - 266.51/1.68 - 266.49/3.36 - 266.49/0.84 - 266.47/0.84 - 266.46/0.84 - 266.45/0.84 -
# 4 /10.0 - 267.03/0.84 - 267.03/0.84 - 267.02/0.84 - 267.01/1.68 - 267.02/3.36 - 267.01/0.84 - 267.00/0.84 - 266.99/0.84 - 266.98/0.84 -
# 5 /12.5 - 267.10/0.84 - 267.10/0.84 - 267.09/0.84 - 267.08/1.68 - 267.09/3.36 - 267.07/0.84 - 267.07/0.84 - 267.06/0.84 - 267.05/0.84 -
# 6 /15.0 - 267.17/0.84 - 267.17/0.84 - 267.16/0.84 - 267.15/1.68 - 267.15/3.36 - 267.14/0.84 - 267.12/0.84 - 267.12/0.84 - 267.12/0.84 -
# 7 /17.5 - 267.22/0.84 - 267.21/0.84 - 267.22/0.84 - 267.21/1.68 - 267.18/3.36 - 267.17/0.84 - 267.15/0.84 - 267.14/0.84 - 267.14/0.84 -
# 8 /20.0 - 267.77/0.84 - 267.77/0.84 - 267.77/0.84 - 267.76/1.68 - 267.77/3.36 - 267.76/0.84 - 267.75/0.84 - 267.75/0.84 - 267.75/0.84 -
# 9 /22.5 - 267.84/0.87 - 267.83/0.87 - 267.83/0.87 - 267.81/1.74 - 267.81/3.48 - 267.81/0.87 - 267.79/0.87 - 267.79/0.87 - 267.79/0.87 -
# 10 /25.0 - 267.91/0.87 - 267.89/0.87 - 267.89/0.87 - 267.89/1.74 - 267.88/3.48 - 267.87/0.87 - 267.87/0.87 - 267.85/0.87 - 267.85/0.87 -
you can see there is alot of variation in the data.
the first 438 Geopoints were used to layout the shape of the road,disregarding altitude changes and focusing on the curves,layed out in the sattelite view.Geopoint #439 follows these points to give you an accurate straight-line measurement with #440 (the centerline Geopoint).
the altitude data is then changed manually in BTB from the 4-screen view and moving the points to the corresponding altitude from either of the 2 lower screens.
very tediouse but extremely accurate.