int outSize = 200;

field#0(2)[] F = tent ⊛ load("../../data/ddro-115.nrrd");

strand sample (int ui, int vi) {
   real uu = lerp(0.0, 1.0, -0.5, real(ui), real(outSize)-0.5);
   real vv = lerp(0.0, 1.0, -0.5, real(vi), real(outSize)-0.5);
   vec2 pos = [uu, vv];
   output real val = -1.0; 

   update {
      val = F(pos) if (inside(pos,F)) else -1.0;
      stabilize;
   }
}

initially [ sample(ui, vi) | vi in 0..(outSize-1), ui in 0..(outSize-1) ];