Class: QgsElevationMap

class qgis.core.QgsElevationMap

Bases: sip.wrapper

Stores digital elevation model in a raster image which may get updated as a part of map layer rendering process. Afterwards the elevations can be used for post-processing effects of the rendered color map image.

Elevations are encoded as colors in QImage, thanks to this it is not only possible to set elevation for each pixel, but also to use QPainter for more complex updates of elevations. We encode elevations to 24 bits in range of [-7900, 8877] with precision of three decimal digits, which should give millimiter precision and enough range for elevation values in meters.

Added in version 3.28.

QgsElevationMap() Default constructor

QgsElevationMap(size: QSize, devicePixelRatio: float = 1) Constructs an elevation map with the given width and height

QgsElevationMap(image: QImage) Constructs an elevation map from an existing raw elevation image. The image must have ARGB32 format and obtained by the rawElevationImage() method.

See also

rawElevationImage()

Added in version 3.30.

QgsElevationMap(other: QgsElevationMap) Copy constructor

Methods

applyEyeDomeLighting

Applies eye dome lighting effect to the given image.

applyHillshading

Applies hill shading effect to the given image.

combine

Combines this elevation map with otherElevationMap.

decodeElevation

Converts a color back to elevation value

encodeElevation

Converts elevation value to an actual color

isNoData

Returns whether the encoded value is a no data value

isValid

Returns whether the elevation map is valid.

noDataValue

Returns the no data value for the elevation map

painter

Returns painter to the underlying QImage with elevations

rawElevationImage

Returns raw elevation image with elevations encoded as color values
applyEyeDomeLighting(self, image: QImage, distance: int, strength: float, rendererScale: float)

Applies eye dome lighting effect to the given image. The effect makes angled surfaces darker and adds silhouettes in case of larger differences of elevations between neighboring pixels.

The distance parameter tells how many pixels away from the original pixel to sample neighboring pixels. Normally distance of 2 pixels gives good results.

The strength parameter adjusts how strong the added shading will be. Good default for this value seems to be 1000.

The rendererScale parameter adjusts scale of elevation values. It is recommended to set this to the map’s scale denominator to get similarly looking results at different map scales.

Parameters:

  • image (QImage)

  • distance (int)

  • strength (float)

  • rendererScale (float)

applyHillshading(self, image: QImage, multiDirectional: bool, altitude: float, azimuth: float, zFactor: float, cellSizeX: float, cellSizeY: float)

Applies hill shading effect to the given image.

If the multidirectinal parameter is True, the algorithm will considered a multi horizontal directional light to apply the shading.

The parameter altitude (could also be named zenith) is the vertical direction of the light.

The parameter azimuth is the horizontal direction of the light considered if multidirectional is False.

The parameter zFactor is the vertical exageration of the terrain.

The parameters cellSizeX and cellSizeY are the sizes of the elevation map cells in unit consistent with the unit of the encoded elevation in this elevation map.

Added in version 3.30.

Parameters:

  • image (QImage)

  • multiDirectional (bool)

  • altitude (float)

  • azimuth (float)

  • zFactor (float)

  • cellSizeX (float)

  • cellSizeY (float)

combine(self, otherElevationMap: QgsElevationMap, method: Qgis.ElevationMapCombineMethod)

Combines this elevation map with otherElevationMap. This elevation map keeps its size and takes elevation values of otherElevationMap that is not null for same row and column following the combine method. The other elevation map can have a different size, only rows and columns contained in this elevation map will be considered.

Added in version 3.30.

Parameters:
decodeElevation(colorRaw: int) → float

Converts a color back to elevation value

Parameters:

colorRaw (int)

Return type:

float

encodeElevation(z: float) → int

Converts elevation value to an actual color

Parameters:

z (float)

Return type:

int

isNoData(self, colorRaw: int) → bool

Returns whether the encoded value is a no data value

Parameters:

colorRaw (int)

Return type:

bool

isValid(self) → bool

Returns whether the elevation map is valid.

Added in version 3.30.

Return type:

bool

noDataValue(self) → float

Returns the no data value for the elevation map

Return type:

float

painter(self) → QPainter

Returns painter to the underlying QImage with elevations

Return type:

QPainter

rawElevationImage(self) → QImage

Returns raw elevation image with elevations encoded as color values

Return type:

QImage