Hi Daniela,
possible solution:
1. run the "Union" algorithm that splits the input polygons
2. add a new integer-column to the "Union"-result-layer f. e. "num_overlays"
3. optionally an additional column with type "integer list" or "string",
if You want to see afterwards, which features intersect, f. e.
"overlay_ids"
4. run the script below, that performs a self-intersection for each
feature to find the spatial identical overlaps (Note: Layer- and
column-names hard coded, adjust if necessary)
union_layer = QgsProject.instance().mapLayersByName('Union')[0]
union_layer.startEditing()
for union_feature_1 in union_layer.getFeatures():
num_overlays = 0
overlay_ids = []
for union_feature_2 in union_layer.getFeatures():
if
union_feature_1.geometry().equals(union_feature_2.geometry()) and
union_feature_1.id() != union_feature_2.id():
num_overlays += 1
overlay_ids.append(union_feature_2.id())
union_feature_1['num_overlays'] = len(overlay_ids)
# solution for column type "string" instead of "integer list":
# union_feature_1['overlay_ids'] = ','.join(str(id) for id in
overlay_ids)
union_feature_1['overlay_ids'] = overlay_ids
union_layer.updateFeature(union_feature_1)
union_layer.commitChanges()
hth
Ludwig
Am 18.08.23 um 16:15 schrieb Daniela Friebel via QGIS-User:
Dear Community
I have a vectorlayer with many objects (polygons) that overlap. Now I
want to create a new layer, where each overlap results in a separate
object, which has an attribute with the number of overlaps.
I have already tried various things, but have not yet found a
solution. With the "union" tool I can generate the overlaps as
objects, but I cannot count the number of overlaps.
I am grateful for any help and hints.
(I would like to count the overlaps to eventually create a heatmap. If
there is a completely different way of doing this, I would also
appreciate a tip).
Kind regards
Daniela
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