QGIS, a powerful GIS tool, is an essential artifact in the development of geographic information. Today, Nanjing City is used as an example to make administrative divisions and use electronic maps as digital base maps for presentation.
1. Obtain administrative division data
Alibaba Cloud's visualization platform provides a convenient way to obtain data on China's administrative divisions, with the smallest data level down to the district and county levels.
After opening the website, select the desired administrative division range.
You can directly download the json file, which is in GeoJson format, and can be directly dragged to QGIS to open.
You can also open the website https://mapshaper.org/ and copy the json data over.
The effect after analysis is as follows:
the current administrative division data can be exported as a shp file for QGIS to use.
2. Create a digital basemap
Taking Nanjing City as an example, using an online electronic map as a digital base map
2.1 Use QGIS cloud service to add background layer
Install the QGIS Cloud Plugin. Select "Plugins > Install and Manage Plugins", search for and install the QGIS Cloud Plugin plugin, which is a cloud service plugin for QGIS, providing a variety of online maps, all of which are foreign maps.
Select "Add background layer" in the QGIS Cloud plugin panel.
2.2 Use local data as background layer
In addition to using cloud online data, QGIS can also use local offline data. Geospatial data cloud provides rich offline map resources.
Take the 30M resolution DEM elevation terrain data as an example, select the required map and download it directly.
After the downloaded file is decompressed, it can be opened directly in QGIS, and the default is grayscale mode.
3. Create administrative division layer
Use QGIS to open the GeoJson file or shp file obtained in step 1, and the default effect after adding the background layer is as follows.
Switching to another background layer has the following effect:
The effect is relatively monotonous, and the effect is reproduced by adjusting the properties of the administrative division layer below.
Right-click on the administrative division layer and select "Properties", select the "Symbolization" tab, and adjust the fill and stroke.
Among them, "Symbolization" provides a variety of style modes to choose from, such as coloring according to classification.
The effect is as follows:
Select the "Dimension" tab to adjust the dimension text size and style.
In addition, different effects can also be presented by using different digital maps as background layers.
The effect of using the offline DEM map as the background layer in pseudo-color mode:
The effect of using the offline DEM map as the background layer in contour mode:
For the ideal map, you can choose to export it as a local file.
