Overview maps within atlas

Question

I have been working with the atlas generation option in QGIS for some time and it works great! What I cannot figure out is how to incorporate the overview function into it.

Here is an example of what I want to get. I want to generate an atlas of 10 different UTM grids. One map per grid. On each map I want a zoom-in overview map to the shapefile labeled with numbers on the map. However when I move on to the next UTM grid in my atlas generator, the overview is still on the old location. Here I would like an overview map showing number 17 to 19, not 9 and 11, since they are no longer in the scope of this map.

If I make the overview map to be selected by the atlas I can only have it selected by the same UTM grid I have for my main map, which is off course not very usefull. Any thoughts on how to get this done? Feels like I should be able to do some conditional formatting on the atlas generation level.

Answer 1

So I found a workaround.

1. I creathed a new shapefile of polygons envelopping all of my point locations/small polygons.
2. I drew two maps and made both controlled in atlas by the newly drawn shape
3. I set the scale of one of them to fixed and the other to a certain % around the polygon.

he maps are still centered around the polygons rahter than the UTM grids, but with some smart labeling I managed to make it workable.

Answer 2

If you want to make a map based on the utm grids you will have to greate a vector storage (shapefile or other) in which every grid (zone) is a separate object. The atlas functionality will not work with points data. Both maps (detail and overview) will have to be controlled by the atlas.

The only difference is the margin around the feature. You will find the setting under the "Item properties". For a fully fledged example you are advised to take a look at this github project where the setup should provide you with a decent point of reference. Note that after syncing the github project you will have to download the most recent overview of protected areas for Tanzania from this website.

Answer 3

I did have same kind of problem and i found a solution that worked for me. It offer the possibility to have two map depending on atlas feature but not centered on it (like you want one have to follow a gird).

For one map (the smallest in your case) you use simply the extent control by atlas. For the second map you set the extent definition (min X, min Y, max X and max Y) depending on attributes of your atlas feature.

You can access any attribute of your atlas feature trough a formula.

For example : attributes(@atlas_feature) ['x_map_min']

You just have to choose the best solution to store in each atlas feature the extent definition (by hand or using join and so)