Converting between raster and vector formats allows you to make use of both raster and vector data when solving a GIS problem, as well as using the various analysis methods unique to these two forms of geographic data. This increases the flexibility you have when considering data sources and processing methods for solving a GIS problem. To combine a raster and vector analysis, you need to convert the one type of data to the other. Let’s convert the raster result of the previous lesson to a vector. The goal for this lesson: To get the raster result into a vector that can be used to complete the analysis. Start with the map from the last module, raster_analysis.qgs. There you should have the all_conditions_simple.tif calculated during the previous exercises. Now you have a vector file which contains all the values of the raster, but the only areas you’re interested in are those that are suitable, i.e., those polygons where the value of suitable is 1. You can change the style of this layer if you want to have a clearer visualization of it. Although unnecessary for our current problem, it’s useful to know about the opposite conversion from the one performed above. Convert to raster the suitable_terrain.shp vector file you just created in previous step. Converting between raster and vector formats allows you to widen the applicability of data, and need not lead to data degradation. Now that we have the results of the terrain analysis available in vector format, they can be used to solve the problem of which buildings we should consider for the residential development. Source.