countintersectionqgis
I am trying to find a way with QGIS to get the intersection area of more than 2 layers.
All the tools in QGIS take just the 2 input layers.
For example in the image below, I have 4 layers and I want to retrieve just the black area.
Furthermore, I need to retrieve the count attribute and add it to the intersected area attribute table (in this case 4)
I know there is a tool that does the trick in ArcGIS, but is there a QGIS solution?
SAGA - vector polygon tools - intersection is my friend. It creates a new Layer without stopping because of errors. Now, I have to delete features with small areas from the new layer.
Go to Settings > Options > Processing and under General change to Ignore features with invalid geometries.
Alternatively, it's also worth checking the answer by A.Oikonomidis as well as other tools available in the processing toolbox to fix invalid geometries in the original dataset.
Best Answer
For a layer's feature to be represented in all layers it must be represented in any selection of two layers a well. Using this theory you can simply run multiple intersection functions according to the order below. The example assumes 4 total layers named Layer1, Layer2, Layer3, and Layer4.
Output 3 should contain all features that appear in all 4 layers. For the 'Count' field, I think you can just file it with the number of layers involved in the intersect, unless I am mistaking what data you want that field to hold.
This method isn't eloquent and if you have many layers or layers with many features it could prove time consuming but it should work and is a simple process to put together.