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To meet the special requirement in dynamic visualization of the terrain such as excavating and filling, an extending
technique of the terrain visualization based on Fractal LoD (Level of Detail) is proposed. Firstly, a dynamic triangulation
algorithm for the view-dependent and the real-time LoD model of the terrain is present, which is based on the GRID
DEM, constructs the continuous LoD with bintree structure according to the screen error criterion, and the 'crack' is
covered by building the dependent relationships of the different vertexes based on the directed acyclic graph (DAG),
which aim is to render the whole terrain with the static data. Secondly, an extending algorithm based on the fractal is
proposed, which can render more detail part of a special region. At beginning, the fractal dimension is calculated
according the flatness of the regional surface, then 'Diamond-Square' algorithm is disposed to get the extending vertexes
of the deformed region and its transitional regions according the fractal dimension and refinement degree. In order to
solute the problem of the 'crack' and 'T-junction' caused by the discontinuities between the two steps, an extensional
DAG and an extensional bintree structure based on the extensional vertexes are build according a extensional screen
error criterion which is smaller. Lastly, the complete implement method is given.
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