function Mask=CalcMeshMask(CtrlVar,MUA,NodalField,Threshold)

Mask=CalcMeshMask(CtrlVar,MUA,NodalField,Threshold)

In general a (nodal) mask is an nodal array of values between 0 and 1 indicating if a the value of the NodalField at a given node is lower or higher than the specified Threshold.

Here both an element and a nodal mask is calculated for the NodalField based on the value of Threshold.

Mask is returned as a logical array where:

Mask.NodesOn : True for nodes belonging to elements where SOME of the nodal values are above AND SOME below the Threshold

Mask.NodesIn : True for nodes belonging to elements where ALL of the nodal values are above the Threshold

Mask.NodesOut : True for nodes belonging to elements where ALL of the nodal values are below the Threshold

A corresponding element mask is also returned.

This definition of In/Out is sometimes also referred to as being 'strictly' above or 'strictly' below a given threshold value.

Typical uses involve calculating nodes above and below the grounding line based on the NodalField F.GF.node, e.g.

Mask=CalcMeshMask(CtrlVar,MUA,F.GF.node,0.5) ;

or to find nodes and elements above and below the calving front if one uses the level-set method, e.g.

Mask=CalcMeshMask(CtrlVar,MUA,F.LSF,0) ;

Example: Create a mask based on ice thickness above and below 100.

load PIG-TWG-RestartFile.mat
CtrlVar=CtrlVarInRestartFile;
Mask=CalcMeshMask(CtrlVar,MUA,F.h,100);

FindOrCreateFigure("Nodal Mask") ;
CtrlVar.PlotNodes=0; CtrlVar.WhenPlottingMesh_PlotMeshBoundaryCoordinatesToo=0;
PlotMuaMesh(CtrlVar,MUA) ;
hold on ;
x=MUA.coordinates(:,1) ; y=MUA.coordinates(:,2) ;
p1=plot(x(Mask.NodesIn)/CtrlVar.PlotXYscale,y(Mask.NodesIn)/CtrlVar.PlotXYscale,'or','DisplayName','In');
p2=plot(x(Mask.NodesOn)/CtrlVar.PlotXYscale,y(Mask.NodesOn)/CtrlVar.PlotXYscale,'og','DisplayName','On');
p3=plot(x(Mask.NodesOut)/CtrlVar.PlotXYscale,y(Mask.NodesOut)/CtrlVar.PlotXYscale,'ob','DisplayName','Out');
legend([p1 p2 p3])

narginchk(3,6)
nargoutchk(1,4)

if isempty(NodalField)
    Mask=[];
    return
end


EleValue=Nodes2EleMean(MUA.connectivity,NodalField);

CtrlVar.GLthreshold=Threshold ; % need this in GLgeometry
Mask.Level=CtrlVar.GLthreshold;
[Mask.Geo,Mask.NodesOn,Mask.ElementsOn]=GLgeometry(MUA.connectivity,MUA.coordinates,NodalField,CtrlVar);

Mask.ElementsIn=   (EleValue>Mask.Level)  & ~Mask.ElementsOn;
Mask.ElementsOut= (EleValue<Mask.Level)  & ~Mask.ElementsOn;


Mask.NodesIn=false(MUA.Nnodes,1);
Mask.NodesOut=false(MUA.Nnodes,1);

Mask.NodesIn(MUA.connectivity(Mask.ElementsIn,:))=true;
Mask.NodesOut(MUA.connectivity(Mask.ElementsOut,:))=true;


Mask.NodesOut=Mask.NodesOut & ~Mask.NodesOn;
Mask.NodesIn=Mask.NodesIn & ~Mask.NodesOn;


return

Error using CalcMeshMask (line 55)
Not enough input arguments.

end

Published with MATLAB® R2025a