Zonal Statistics miscalculates when handling polygons without raster cells within its boundaries - Githubissues

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Zonal Statistics miscalculates when handling polygons without raster cells within its boundaries #21149

Closed qgib closed 5 years ago

qgib commented 9 years ago

Author Name: Tobias Klinge (Tobias Klinge) Original Redmine Issue: 13081 Affected QGIS version: master Redmine category:analysis_library

I believe the title says it all. Working with the attached sample data, Zonal Statistics ended up calculating means, medians etc. for polygons (no apparent geometry issues) that have no valid raster cells underneath. Note, however, that this does not happen all the time since some returns were indeed NULL (as they should be). One indicator for faulty results is clearly that count returns floats instead of integers. Except for this, the plugin worked fine - thanks again for expanding its options. Hopefully, this can be resolved quickly. Best regards tjk

data.zip (Tobias Klinge)

qgib commented 9 years ago

Author Name: Giovanni Manghi (@gioman)

This is confirmed to affect the core c++ plugin, while the same tool in the Processing toolbox seems ok.

category_id was configured as 115
priority_id was changed from Normal to High
version was changed from 2.10.0 to master
crashes_corrupts_data was changed from 0 to 1

qgib commented 8 years ago

Author Name: Alexander Bruy (@alexbruy)

In fact almost all polygons in the attached dataset have raster within their boundaries, but this is NODATA value. Even plogon in the middle of the raster has wrong statistics.

And I can not reproduce this bug with clipped part of the attached raster/vector layers.

tag was changed from zonal-statistics to

qgib commented 7 years ago

Author Name: Giovanni Manghi (@gioman)

category_id was changed from 115 to Analysis library

qgib commented 7 years ago

Author Name: Giovanni Manghi (@gioman)

fixed_version_id was configured as Version 3.0

qgib commented 7 years ago

Author Name: Giovanni Manghi (@gioman)

Results are correct on 2.18.4 on both Linux and Windows.

crashes_corrupts_data was changed from 1 to 0
status_id was changed from Open to Closed
priority_id was changed from High to Normal
resolution was changed from to worksforme