SMS:Telescoping Grids

One of the most restrictive attributes of a Cartesian grid is the limited variability in resolution. By the purest definition, a Cartesian grid consists of square cells, meaning a constant resolution over the entire domain. A method that can be employed to support variable resolution involves the creation/use of what can be called a Telescoping Grid (sometimes referred to as a Quad Tree). The CMS-Flow model is the only numeric engine currently supported by the SMS which allows computation on a telescoping grid.

The generation of a telescoping grid involves:

• A base grid
• Refinement features

Base Grid

The SMS generates a telescoping grid from a user defined base grid. The user defines this base grid with the approach that is used in any other grid generation operation in the SMS consisting of the definition of a grid frame and either a base cell dimension or number of cells in each of the coordinate directions (I,J)

Refinement Features

with constant cell size (rectangular or square cells) serves as the background resolution. This base grid is the first parameter for generation of 

CMS-Flow can use a grid with varying resolution which is referred to as a telescoping grid.

Telescoping grids are created by creating polygons where the user wants the different levels of refinement in a CMS-Flow coverage. Each polygon is assigned the maximum allowable size for cells in this area. When using Map→2D Grid, specify the size of the base grid. SMS will build a telescoping grid with as many levels as required to satisfy the constraints imposed by the polygons.

Telescoping grids have a base grid with a specified cell size. The cells in the child grid of the base grid have half the cell size (half in both I and J directions). This means each cell is divided into 4 cells.

Note: Telescoping grids in SMS 11.0 are introduced with limited capability and no support. There are known issues such as problems with shading that will not be addressed in SMS 11.0.