\begin{tikzpicture}[
	scale=0.9,
	x={(-10:1cm)},y={(220:1cm)},z={(90:1cm)},
	coarse/.style={circle,draw=black,inner sep=2},
	fine/.style={cross out,draw=black,inner sep=1},
]

\draw[opacity=0.5,dotted] (0,0,-2) -- (0,0,0);
\draw[opacity=0.5,dotted] (0,5,-2) -- (0,5,0);
\draw[opacity=0.5,dotted] (5,0,-2) -- (5,0,0);
\draw[opacity=0.5,dotted] (5,5,-2) -- (5,5,0);

\draw[opacity=0.5,dotted] (1,1,-2) -- (1,1,4);
\draw[opacity=0.5,dotted] (1,4,-2) -- (1,4,4);
\draw[opacity=0.5,dotted] (4,1,-2) -- (4,1,4);
\draw[opacity=0.5,dotted] (4,4,-2) -- (4,4,4);

\draw[opacity=0.5,dotted] (1.5,1.5,-2) -- (1.5,1.5,2);
\draw[opacity=0.5,dotted] (1.5,3.5,-2) -- (1.5,3.5,2);
\draw[opacity=0.5,dotted] (3.5,1.5,-2) -- (3.5,1.5,2);
\draw[opacity=0.5,dotted] (3.5,3.5,-2) -- (3.5,3.5,2);

\begin{scope}[xyp=-2]
\foreach \x in {0,...,10}
	\foreach \y in {0,...,10}{
		\ifthenelse{\x>6 \OR \x<4 \OR \y>6 \OR \y<4}{
			\node[coarse] at (0.5*\x,0.5*\y){ };
		}{}
	}

\foreach \x in {0,...,12}
	\foreach \y in {0,...,12}{
		\node[fine] at (1+0.25*\x,1+0.25*\y){ };
	}

\node[right] at (6,0) {Gitter \(\G\) und \(\F\)};
\end{scope}

\begin{scope}[xyp=0]
\fill[opacity=0.6,gray,even odd rule] (0,0) rectangle (5,5) (1.5,1.5) rectangle (3.5,3.5);
\draw[thick,even odd rule] (0,0) rectangle (5,5) (1.5,1.5) rectangle (3.5,3.5);
\draw[dashed] (1,1) rectangle (4,4);
\draw[pattern=north east lines,even odd rule] (1,1) rectangle (4,4) (1.5,1.5) rectangle (3.5,3.5);

\node[right] at (6,0) {Grobe Domäne \(D_g\)};
\end{scope}

\begin{scope}[xyp=2]
\fill[thick,opacity=0.6,gray,even odd rule] (1,1) rectangle (4,4) (1.5,1.5) rectangle (3.5,3.5);
\draw[thick] (1,1) rectangle (4,4) (1.5,1.5) rectangle (3.5,3.5);

\node[right] at (6,0) {Übergangsbereich \(D_g \cap D_f\)};
\end{scope}

\begin{scope}[xyp=4]
\draw[thick] (1,1) rectangle (4,4);
\fill[opacity=0.6,gray] (1,1) rectangle (4,4);

\node[right] at (6,0) {Feine Domäne \(D_f\)};
\end{scope}

\end{tikzpicture}