TopoUSM

Ambient shader for Digital Elevation Models

14 July 2018: QGIS Plugin version is almost coming! See demo.

2017: Reference code available in Python 3

Fumihiko Ikegami

Enabling both improved shading and enhanced visualization

Hillshade vs TopoUSM.

Slope vs TopoUSM. Works fine on LatLon grid.

How it works

Each pixel represents residual z-value from the "unsharped" terrain.

Ridges get highlighted while valleys and basins get darkened, as such illuminated by ambient light.

Logarithmic dynamic range compression may be applied to reduce the whitening of cones.

Adjusting r (radius) enables you to control which features in different scales to be enhanced.

In the larger r, sparse sampling may be used to improve the processing speed.

Composite of TopoUSM layers in optimal balance is visually scalable. Hard to get saturated by microtopography when it is zoomed-out.

Application to 3D models

AW3D30 DSM (JAXA) in BlenderGIS with TopoUSM textures

References of the data used in the pictures:

Red Sea and Arabian Shield - GEBCO 2014 Grid
Big Obsidian Flow, Newberry volcano - DOGAMI LiDAR Quadrangle Series & USGS Topo Map
Mt. St. Helens - University of Washington Library
Bali Island - JAXA ALOS World 3D 30m DSM (AW3D30)
Rock Mesa, South Sister volcano - DOGAMI LiDAR Quadrangle Series
Southern Japan - GEBCO 2014 Grid
Dome O, Havre caldera

All rights reserved for these pictures.

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