int ires=200;

field#2(3)[3,3] V= c4hexic ⊛ image("slab-c4h-ten9-small.nrrd");
field#2(3)[] F = det(V);



strand raycast(int ui, int vi) {
   output real out=F([ui,vi,1]);

  update {

      stabilize;
    }
}
initially [ raycast(ui, vi) | vi in 0..ires-1, ui in 0..ires-1 ];