Generalizing  Terrain  Representa0ons  with  Vector  Sums

Patrick  Kennelly  Long  Island  University  

Generalizing  Terrain  Representa0ons  with  Vector  Sums

•  The  importance  of  generalizing  terrain  representa<ons  

•  Approaches  for  generalizing  relief  shading  •  A  new  method  for  generalizing  relief  shading  

in  vector  space  

Approaches  for  Generalizing  Relief  Shading

•  Smooth  the  relief  shaded  map  •  Smooth  the  terrain  then  relief  shade  •  Smooth  the  surface  normal  vector  then  relief  

shade  

Smooth  the  Relief  Shaded  Map

Smooth  the  Relief  Shaded  Map

Smooth  the  Relief  Shaded  Map

15  x  15  kernel  

Smooth  the  Terrain  then  Relief  Shade

Smooth  the  Terrain  then  Relief  Shade

15  x  15  kernel  

Smooth  the  Terrain  then  Relief  Shade

Leonowicz,  A.  M.,  Jenny,  B.,  &  Hurni,  L.  (2010).  Terrain  sculptor:  generalizing  terrain  models  for  relief  shading.  Cartographic  Perspec/ves,  (67),  51-­‐60.  

• Low-­‐pass  mean  filter  • Curvature  coefficients  to  iden<fy  valleys  and  ridges  • Ver<cally  exaggerate  and  deepen  smoothed  terrain  model  • Mountain  and  lowland  grids  create  with  weigh<ng  factors  applied  to  exaggerated/deepened  and  smoothed  grids  • Grids  recombined  with  smoothed  slope  grid  • Shaded  relief  created  from  recombined  grid  

Smooth  the  Terrain  then  Relief  Shade Terrain  Sculptor

Smooth  the  Surface  Normal  Vector    then  Relief  Shade

Smooth  the  Surface  Normal  Vector    then  Relief  Shade

Smooth  the  Surface  Normal  Vector    then  Relief  Shade

15  x  15  kernel  

Summary A  low  pass  filter  employing  a  large  (15x15)  kernel  can  be  used  to  sum  surface  normal  vectors  in  a  manner  that  results  in  smoothed  relief  shaded  maps  Results  compare  with  hand-­‐drawn  methods  and  methods  sculp<ng  terrain  for  final  relief  shading  The  result  is  a  relief  shaded  map  -­‐  -­‐    no  analogous  smoothed  terrain  model  exists