Merge pull request #65020 from qgis/backport-64988-to-release-3_44

[Backport release-3_44] Use default classification classes when there are no statistics

Author: alexbruy

src/gui/pointcloud/qgspointcloudclassifiedrendererwidget.cpp

@@ -527,6 +527,16 @@ void QgsPointCloudClassifiedRendererWidget::addCategories()
   const QgsPointCloudCategoryList defaultLayerCategories = isClassificationAttribute ? QgsPointCloudRendererRegistry::classificationAttributeCategories( mLayer ) : QgsPointCloudCategoryList();
 
   mBlockChangedSignal = true;
+
+  // If it is classification and we lack stats, lets use the full set of default categories
+  if ( isClassificationAttribute && providerCategories.isEmpty() )
+  {
+    for ( const QgsPointCloudCategory &c : defaultLayerCategories )
+    {
+      providerCategories.append( c.value() );
+    }
+  }
+
   for ( const int &providerCategory : std::as_const( providerCategories ) )
   {
     // does this category already exist?