Loading of data and formation of bases layer for buffering of data

The term background usually refers to data that we are not the authors of, and we use them to help us in our work, research, processing or publication of data. Most often, we are talking about raster bases in the form of topographic maps, surface models (DEM), pedological maps and various spatial data (borders of states, municipalities) intended for easier finding or processing and visualization of author's data.

OSM map data can be downloaded at once for all vector layers via the website extract.bbbike.org. Also, the data that has been loaded should be saved in the EPSG:4326 projection (Export → Save Features as and the Shapefile data type can be selected). There is a possibility of downloading data through the QuickOSM plugin, available in QGIS, but for this work it was not possible because a smaller area can be downloaded from the OSM map, while bbbike.org offers the possibility of downloading larger territories, states.

Other data that will be used were collected in the field through the input application and merge service, which was explained in the previous blog. We will use substation coordinates and certain attributive data for data.

The buffer tool is often used in QGIS, which produces a new vector polygon layer, representing a certain distance from the input features. It can be used to identify proximity to certain features.

In this step, a buffer zone is created around the streets in the Banja Luka area at a distance of 10m in accordance with the defined substation coordinates. The option Vector → Geoprocessing Tools → Buffer is used to define the buffer zone. In addition to this option, there is also a related Variable width buffer option that is used when it is necessary to define a buffer zone of different width for different entities. Then the M value is taken as the distance value, which usually represents the temporal dimension of an entity (in addition to the spatial coordinates X, Y and Z)

In the window for setting buffer parameters, it is necessary to set the input file over which the buffer is created (Input layer), the distance value (Distance) and the output file (Buffer). If the Open output file after running algorithm box is checked, the resulting layer will be automatically loaded into the current project. Enter 0.00010 for the value of the band around the track, leave the Dissolve result option enabled so that the layer is merged in the form of a buffer polygon, and leave the other settings at the default values. The resulting layer needs to be adjusted to the appropriate coordinate system.

Spatial association is a spatial analysis where, based on the location, the attributes of entities of one layer that are in some relationship with the entity of another layer can be aggregated. The Join attributes by location (summary) function is located in the Vector general Processing Toolbox command group. Here you can determine the total number of substations (points) that fall into the buffer route, the sum of all substations, etc. It is important to first select the layer within which the buffer is located and then the ts from which the attribute values will be aggregated.

It is possible to specify which attributes will be used for the calculation - by clicking on Join type, take attributes of the first matching feature only (one-to-one) attributive data will not be duplicated, which would prevent the operation of the database. As a result, a new layer is obtained that contains newly generated attributes with a summary of attribute values by individual statistics.