Multi-Point Sky Illumination

Cindy Brewer, Jay McGilloway, Rick Fourroux Penn State Geography

Prepared for April 2012 meeting with USGS

(K. Fishburn, E. Finelli, M. Cooley)

NE 45_45

N 0_45

W 270_45

SE 135_60

NW 315_45 (default)

5 Point NW Weighted Hillshade with Curvature

From left to right- • Curvature • Curvature and hillshade • Hillshade

120 Point Hillshade with Curvature

• 15° azimuth increments – 24 directions

• 5 altitudes - 10°, 25°, 40°, 55°, 70°

• Additional weighting on NW directions from 285°-345°

5 point 120 point

NW 5 point with curvature

5 point 5 point @ 70% transparency

Other Examples Images on left:

• Standard Arc default hillshade:

- Azimuth of 315° - Sun angle (elevation) of 45°

Black to white color ramp

Images on right: • 5 point illumination model • Raster calculated with illumination

directions of: 45°, 45°(NE) 135°, 60°(SE) 0°, 45°(N) 270°, 45°(W) 315°, 45°(NW)

• Curvature

The hillshade layers have a transparency of 10% to allow the curvature to come through. Black to white color ramps on both.

Black Point, UT

Chamblee, GA

Branford, CT

Granite City (E. St.Louis)

Hermitage, MO

Memphis, TX

Spooner, GA

Squares S Ranch, CO