Draw an ASCII contour plot
Mathematica, 353 326 bytes

s=Table[".",3,3];z=Reverse;l@0=l@15=s;y=s;y[[3,1]]="\\";l@1=l@14=y;y=s;y[[3,3]]="/";l@2=l@13=y;y=s;y[[2,All]]="-";l@3=l@12=y;y=l@4=l@11=z/@z@l@1;y[[3,1]]="\\";l@10=y;y=s;y[[All,2]]="|";l@6=l@9=y;y=l@7=l@8=z/@z@l@2;y[[3,3]]="/";l@5=y;StringReplace[ToString@Grid@Map[Column,Map[StringJoin,Map[l,#,{2}],{3}],{2}],{"\n\n"-&gt;"\n"}]&amp;



input


  [{{15, 13, 12, 14, 15}, {13, 8, 0, 4, 14}, {11, 1, 0, 2, 7}, {15, 11, 
     3, 7, 15}}]