How do you manage and organize georeferenced images in QGIS projects and databases?

2 Georeference images

Sometimes, you may have images that are not georeferenced, meaning that they do not have spatial information attached to them. For example, you may have scanned maps, aerial photos, or historical images that you want to use in your QGIS project. In this case, you need to georeference them, which is the process of assigning coordinates and projection to an image based on known reference points. You can use the Georeferencer plugin in QGIS to georeference your images. You will need to load your image, add control points that link the image pixels to the map coordinates, choose a transformation method and a resampling method, and save the output as a georeferenced image.

3 Manage images in layers

Once you have imported and georeferenced your images, you can manage them in layers in your QGIS project. Layers are the basic units of data representation in QGIS, and they allow you to control the visibility, order, style, and properties of your images. You can use the Layers panel to access the layer list, where you can add, remove, rename, group, and reorder your layers. You can also use the Layer menu or the right-click menu to access various options for layer management, such as duplicate, merge, save, export, and edit.

4 Style and classify images

Another important aspect of managing and organizing georeferenced images in QGIS is to style and classify them according to your needs and preferences. Styling and classifying images can help you enhance the appearance, readability, and meaning of your maps. You can use the Layer Styling panel or the Properties dialog to access the styling and classification options for your images. You can choose from different rendering types, such as singleband, multiband, paletted, or hillshade. You can also apply different color ramps, contrast enhancement, transparency, and blending modes. You can also use the Symbology tab to classify your images based on values, categories, or expressions.

5 Analyze and process images

Georeferenced images are not only useful for mapping and visualization, but also for analysis and processing. You can use georeferenced images to perform various spatial operations, such as clipping, masking, reprojecting, resampling, calculating statistics, extracting values, and creating contours. You can use the Raster menu or the Processing toolbox to access various tools for raster analysis and processing, such as Clip Raster by Extent, Raster Calculator, Zonal Statistics, Extract by Mask, and Contour. You can also use the Modeler or the Graphical User Interface (GUI) to create custom workflows and scripts for raster operations.

6 Use images in map layouts

The final step to use georeferenced images in QGIS is to use them in map layouts. Map layouts are the components of QGIS that allow you to create print-ready maps, reports, and atlases. You can use the Layout Manager or the Project menu to access the layout options in QGIS. You can add various elements to your layout, such as map frames, legends, scale bars, north arrows, text boxes, and images. You can use the Item Properties panel or the right-click menu to adjust the settings and attributes of your layout elements. You can also use the Atlas Generation tab to create dynamic maps based on a layer or a feature.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?