I have been looking for a long time for a good explanation of a spatio-temporal filter or join in QGIS. In my specific case I have two shapefiles (polygons) - one describes the ignitions and the other represents fire perimeter. Both layers also include an attribute called year in which the two occurred.

My goal is to filter out the fire polygons that do not match the ignition both spatially but also temporally.


I have tried this by converting my ignitions to points, but that did not solve the issue.

How can I easily perform a spatial and temporal filter/join of the two polygon layers in QGIS?

My plan is to look at how the timing of ignitions may change over a time period, therefore, I want to look at how the timing of ignitions is for each year. I can also look at the average size of the fires that the ignitions have started for each year.

  • 1
    Since each ignition has a corresponding fire, any usual filter will output the whole layer - so I guess you plan to specify the date the fire started? How?
    – Erik
    Mar 9 '21 at 9:24
  • No, each ignition does not necessarily have a corresponding fire. There can be a lack of reporting from firefighters, managers etc. I am not interested in the specific date. Fires in a given area happen one time, and it does not return the years after as the vegetation is gone. So on an annual basis is what I need.
    – Thomas
    Mar 9 '21 at 9:33
  • Please define what you mean by "an annual basis is what I need". Maybe describe what you plan on doing with your filtered layer, so it becomes more clear how the filter should behave.
    – Erik
    Mar 9 '21 at 9:55
  • 1
    If you copy the layer in your case 18 times, and then write as @erik suggests, year = 20XX (by right clicking on the layer you want to filter and choose filter). Then, if you go to the processing toolbox, right-click the clipping tool and choose "batch processing". You can then input all these layers and corresponding clipping masks at once. Meaning that you only have to perform clippiing 1 time for all output.
    – PGerrits
    Mar 9 '21 at 10:13
  • 1
    you can adapt the solution I gave you a few years ago, by changing the date comparison for a simpler year equality between the layers gis.stackexchange.com/questions/345287/…
    – JGH
    Mar 9 '21 at 14:22

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