Vertical exaggeration of Google earth surfaces

[Anonymous]

Hi -

I'm trying to insert a google earth image and earth around some survey
data. The image comes in just fine, just where it's supposed to.
However, the surface that comes in seems to be incorrectly scaled along
the vertical. In other words, the elevations seem to be affected by some
kind of "flattening" value, what you would expect in a profile if the
vertical exaggeration was set less than 1.0. The whole area is quite a
bit lower than the survey indicates, and it's much "flatter" - the hills
aren't as high, and the low spots aren't as low relative to the
surrounding terrain. Make any sense? The horizontal layout of
identifiable spots: creeks, ponds, hills, etc, appear to be in the
correct position. Any ideas? I'm using Civil 3D 2010, sp2, and Google
Earth 5.0.11337.1968 (beta).

Thanks in advance.
Big Dave

[Civil3DReminders_com]

The land could have moved down. There's parts of the San Juaquin Valley that moves down during long droughts due to farmers pumping water out of the ground, so much so that the California Aqueduct is in danger of starting to flow the other direction in the localized area.

Also Google Earth accuracy is based on its source information and how it's added to Google's cloud, which may or may not be accurate.

Christopher

[davevoith]

I have found that google earth surfaces seem to be a dangerous black box of data. The data seems to be fairly inaccurate and there doesn't seem to be any breaklines added. Also there seems to be no documentation of where the data actually came from. Its a cool feature, but to this day I have yet to find a use for it other than very preliminary design.