When the mesh body type is set to 'blob', nodal points are treated as a spherical data set with an estimated center point. During interpolation, the length of radius vectors to unknown points are calculated using different algorithms like Inverse Distance Weighting or iterative algorithms. Adaptation of these algorithms to the spherical coordinate system involves first mapping points to Cartesian coordinates before processing them as usual.
8. First stage is a
preliminary
calculation,
which sets the
same length to a
radius vector to
a point being
calculated as a
length of a
vector to a
closest* known
nodal point.
ITERATIVE ALGORITHMS
* - «closest» in terms of spherical coordinate
system here
9. The second
stage is an
iterative
smoothing itself:
points within a
cell size angle
from known
points stay
where they are,
others gradually
move along their
radius vectors.
ITERATIVE ALGORITHMS
10. So the process is
similar to the
one that takes
place during
conventional
'terrain-like'
mesh
processing. It is
just adapted a
bit for spherical
coordinate
system.
ITERATIVE ALGORITHMS
14. IDW VS PREDICT
Radius vector
to each given
nodal point is
normal to a
surface tangent
plane at this
point, when
algorithm is set
to IDW. So
known points
are local
extrema.
IDW
15. IDW VS PREDICT
The idea of
'predict'
algorithm is to
estimate surface
tangent planes
at given nodal
points.
'Predict'
16. IDW VS PREDICT
Known
points are
not necessarily
local extrema in
case when
'predict'
algorithm is
chosen so result
of interpolation
can be more
convincing.