Graphics Programs Reference
In-Depth Information
Tip
The Earth's magnetic North Pole is constantly moving. When working with
old maps, you may find that the North indicated on these maps does not
allow the features to line up with any existing features. It is possible to
mathematically correct for this; but it can be quite a technical process. In
the case of Byng Inlet, adjustments were made using visual clues from
both the Google Earth snapshot and the historic insurance map. A best-
guess estimate proved quite serviceable and accurate for this model.
FiG 16.3
Before discussing the modeling in depth, it is helpful to learn a bit about how
SketchUp implements terrain data in a model. When SketchUp imports terrain
data, there are actually two sets of data that are imported. First is a flat snap-
shot of how the terrain looks like from satellite observations, and the second
is the actual terrain/elevation data - a skin on which the satellite image is
projected. The view of these layers can be toggled on or of by utilizing the
Toggle Terrain tool on the Google toolbar.
Tip
The above information about how SketchUp implements terrain data is
pointed out here because one needs to remember what surface you are
modeling on. Modeling on the Google Earth layer can cause you to end
up with buildings that are aligned with the ground but not necessarily
vertical as they are in real life. If you are beginning to model using terrain
data imported by Google Earth, unless the land is perfectly flat, it is best
to model on the Google Earth snapshot first and then move to your model
and adjust it to the proper position on the terrain.
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