Three-dimensional real-time graphics are a prevalent technology nowadays, thanks
to the steady rise of processing power and specialized graphics hardware. One of the
goals of computer graphics most sought after and difficult to achieve is to reproduce realistic outdoor environments featuring dense forests.
We obtained the energy transport velocity distribution for a three dimensional ideal cloak
explicitly. Near the operation frequency, the energy transport velocity has rather peculiar
distribution. The velocity along a line joining the origin of the cloak is a constant, while
the velocity approaches zero at the inner boundary of the cloak. A ray pointing right into
the origin of the cloak will experience abrupt changes of velocities when it impinges on the
inner surface of the cloak. This peculiar distribution causes long time delays for beams
passing through the ideal cloak within a geometric optics description.
樣板 B 樹 ( B - tree )
規則 :
(1) 每個節點內元素個數在 [MIN,2*MIN] 之間, 但根節點元素個數為 [1,2*MIN]
(2) 節點內元素由小排到大, 元素不重複
(3) 每個節點內的指標個數為元素個數加一
(4) 第 i 個指標所指向的子節點內的所有元素值皆小於父節點的第 i 個元素
(5) B 樹內的所有末端節點深度一樣
