Calculate the area of a polygon feature in square meters:$area Calculate the total population of a district by summing the population of each census block:sum("population") Calculate the population density of a district by dividing the total population by the area:"population" / $area Calculate...
$area在计算面积的时候会先看当前项目的椭球的设置,如果设置了椭球,那么计算出来的面积就是椭球面积,如果没有设置椭球,那么计算出来的面积就是平面面积。 椭球设置方法如下:依次打开 工程 -- 工程属性 选择常规选项卡 area 函数 详细写法 area($geometry) 官网解释: Returns the area of a geometry polygon object...
Calculating the area of a polygon Creating a spatial index Calculating the bearing of a line Loading data from a spreadsheet Accessing layer metadata Chapter 3. Editing Vector Data Introduction Creating a vector layer in memory Adding a point feature to a vector layer Adding a line feature to a...
Calculating the area of a polygon Creating a spatial index Calculating the bearing of a line Loading data from a spreadsheet Chapter 3. Editing Vector Data Introduction Creating a vector layer in memory Adding a point feature to a vector layer Adding a line feature to a vector layer Adding a...
“If the zone input is a feature dataset, a vector-to-raster conversion will be internally applied to it”。 当单个要素的面积小于或者接近于栅格的cell时,可能会不展示出来。“If the areas of single features are similar to or smaller than the area of single cells in the value raster, in ...
3. Calculating the Area of Polygons A script to calculate the area of each feature in a polygon layer and add this as a new attribute. ##Calculate_Area=name ##Input_layer=vector ##Area_field_name=string area from qgis.core import QgsField, QgsExpression, QgsExpressionContext, QgsExpressionCo...
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“Clip trajectories by extent”still exists but, additionally, we can now also“Clip trajectories by polygon layer” There are two new event extraction algorithms to“Extract OD points”and“Extract OD points”, as well as the related“Split trajectories at stops”. Additionally, we can also“Sp...
I have a eventFilter on the map canvas that works great with a rectangle. It detects the left mouse press to get the start point and as the mouse is moved, it calculates the area of the rectangle and if within a certain range will complete the polygons shape and save to the layer ...