# setAtlas: Construct usual grids on some specific manifolds In FieldSim: Random Fields (and Bridges) Simulations

## Description

The function `setAtlas` constructs usual grids on manifold.

## Usage

 `1` ```setAtlas(object,gridtype,Ng) ```

## Arguments

 `object` a object of class process or manifold; `gridtype` the type of the grid, possible choice `"regular"`, `"random"` or `"visualization"`; `Ng` parameter of the size of the grid, see details.

## Details

We list here the different implemented grids. For `[email protected]=="plane"` we have the `gridtype=="regular"` grid (with the parameter `Ng` returns a regular grid on [0,1]x[0,1] of size `Ng*Ng`), the `gridtype=="random"` grid (uniform random choice of the both coordinates on [0,1], grid of size `Ng*Ng`) and the `gridtype=="visualization"` grid, of size ` (2^Ng +1)*(2^Ng +1)` composed of regular refinments.

For `[email protected]=="sphere"`, we have the following grids: there isn't exist `gridtype=="regular"` grid for a sphere, but a `gridtype=="random"` grid (uniform density sample on the sphere of size `Ng*Ng`) and a `gridtype=="visualization"` grid (sphere-visualization grid on the sphere of size `6*Ng*Ng`, union of the 6 domains centered around one of the 6 triply orthogonal poles, each domain are composed of the heights on the sphere (when they exists) corresponding to the regular mesh [-3/4,3/4]x[-3/4,3/4] of the others two cartesian coordinates).

Finally, for `[email protected]=="hyperboloid"` we have: no `gridtype=="regular"` grid on the hyperboloid, but a `gridtype=="random"` grid (uniform density sample on the sphere of size `Ng*Ng`) and a `gridtype=="visualization"` grid (hyperboloid-vizualisation grid of size `Ng*Ng`, a domain of composed of the height of the hyperboloid corresponding to the regular mesh [-3,3]x[-3,3] of the other two cartesian coordinates)

## Author(s)

Alexandre Brouste (http://perso.univ-lemans.fr/~abrouste/) and Sophie Lambert-Lacroix (http://membres-timc.imag.fr/Sophie.Lambert/).

## References

A. Brouste, J. Istas and S. Lambert-Lacroix (2010). On simulation of manifold indexed fractional Gaussian fields.

`fieldsim`.
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27``` ```# Load FieldSim library library(FieldSim) # Example on the line manifold line<-setManifold("line") str(line) setAtlas(line,"regular",200) str(line) #Example on the fractional Brownian motion line.fBm<-setProcess("fBm-line",0.7) str(line.fBm) setAtlas(line.fBm,"regular",200) str(line.fBm) setAtlas(line.fBm,"random",100) str(line.fBm) setAtlas(line.fBm,"finer",9) str(line.fBm) setAtlas(line.fBm,"visualization",9) str(line.fBm) ```