This tool creates a hypsometrically tinted shaded relief (Swiss hillshading) image from an input digital elevation model (DEM). The tool combines a colourized version of the DEM with varying illumination provided by a hillshade image, to produce a composite relief model that can be used to visual topography for more effective interpretation of landscapes. The output of the tool is a 24-bit red-green-blue (RGB) colour image.
The user must input a DEM. Other parameters that must be specified include the illumination source azimuth (azimuth
), or sun direction (0-360 degrees), the illumination source altitude (altitude
; i.e. the elevation of the sun above the horizon, measured as an angle from 0 to 90 degrees), the hillshade weight (hs_weight
; 0-1), image brightness (brightness
; 0-1), and atmospheric effects (atmospheric
; 0-1). The hillshade weight can be used to increase or subdue the relative prevalence of the hillshading effect in the output image. The image brightness parameter is used to create an overall brighter or darker version of the terrain rendering; note however, that very high values may over-saturate the well-illuminated portions of the terrain. The atmospheric effects parameter can be used to introduce a haze or atmosphere effect to the output image. It is intended to reproduce the effect of viewing mountain valley bottoms through a thicker and more dense atmosphere. Values greater than zero will introduce a slightly blue tint, particularly at lower altitudes, blur the hillshade edges slightly, and create a random haze-like speckle in lower areas. The user must also specify the Z conversion factor (zfactor
). The Z conversion factor is only important when the vertical and horizontal units are not the same in the DEM. When this is the case, the algorithm will multiply each elevation in the DEM by the Z conversion factor. If the DEM is in the geographic coordinate system (latitude and longitude), the following equation is used:
zfactor = 1.0 / (111320.0 x cos(mid_lat))
where mid_lat
is the latitude of the centre of the raster, in radians.
hillshade, multidirectional_hillshade, aspect, slope
def hypsometrically_tinted_hillshade(self, dem: Raster, solar_altitude: float = 45.0, hillshade_weight: float = 0.5, brightness: float = 0.5, atmospheric_effects: float = 0.0, palette: str = "atlas", reverse_palette: bool = False, full_360_mode: bool = False, z_factor: float = 1.0) -> Raster: ...