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