2018-02-01 13:58:55 8 Comments

I am carrying out an analysis using QGIS 2.14.1 where I am dealing with point data that have been randomly displaced by either up to 2 Km or 5 Km. I have generated a buffer of the appropriate radius around each point and now want to obtain mean values for each polygon from a raster layer.

To do this I have used the Zonal Statistics tool but for about 10% of my points no results have been generated even though there is raster data for that location. All the polygons with missing data have a 2 Km radius. The Zonal Statistics tool worked for some of the polygons with a 2 Km radius, just not all. The raster layer I am dealing with has a resolution of 5 X 5 Km.

When I increase the size of the polygon I am able to obtain zonal statistics results, which suggests to me that the size of the polygon may be too small. However, I cannot alter the polygon size because the point can only be within this radius and therefore enlarging the polygon would make the results inaccurate.

I understand that if polygons overlap this can sometimes cause issues. Whilst some of the polygons do overlap, some of them do not. I also tried doing this for one polygon at a time but still did not get results with the ones I tried. I have included an image below where the smaller green polygon is an example of one of the polygons that has missing Zonal Statistics output.

I am aware of multiple other Q&As addressing this type of issue but nothing I have tried has worked so far. The Q&As I have seen are:

- Missing buffer values when using zonal statistics in ArcGIS Desktop?
- Zonal Statistics as a Table does not calculate statistics for all features in dataset?
- Zonal Statistics As A Table missing Features in Results?
- Polygons too Small for Zonal Statistics
- Zonal statistics results in some NULL values in QGIS?

I do not use Python.

### Related Questions

#### Sponsored Content

#### 1 Answered Questions

### [SOLVED] Zonal Statistics is returning null values in ArcGIS Desktop?

**2019-04-26 04:37:25****Esme_****111**View**3**Score**1**Answer- Tags: arcgis-desktop spatial-analyst zonal-statistics null

#### 2 Answered Questions

### [SOLVED] How does Zonal Statistics work exactly?

**2017-09-11 15:57:37****GeoEki****8213**View**9**Score**2**Answer- Tags: qgis raster layers saga zonal-statistics

#### 1 Answered Questions

### [SOLVED] Zones missing after running zonal statistics in ArcGIS Spatial Analyst?

**2017-05-17 14:42:29****Oh-No****279**View**5**Score**1**Answer- Tags: arcgis-desktop spatial-analyst zonal-statistics missing-data

#### 0 Answered Questions

### Zonal statistics results in some NULL values in QGIS?

**2017-04-28 03:11:46****Ichiro****187**View**0**Score**0**Answer- Tags: qgis zonal-statistics null

#### 0 Answered Questions

### Zonal statistics behavior

**2018-01-18 07:20:46****Sumiko****94**View**3**Score**0**Answer- Tags: qgis-processing zonal-statistics

#### 2 Answered Questions

### [SOLVED] Zonal statistics for millions of overlapping polygons in ArcPy?

**2014-09-06 21:24:08****mbcaradima****3276**View**6**Score**2**Answer- Tags: arcpy arcgis-10.1 spatial-analyst overlapping-features zonal-statistics

#### 2 Answered Questions

### [SOLVED] Alternatives to Zonal Statistics which include partial pixels (QGIS)

**2017-02-03 13:46:08****Tim K****823**View**7**Score**2**Answer- Tags: qgis raster pyqgis polygon zonal-statistics

#### 1 Answered Questions

### [SOLVED] Polygons too Small for Zonal Statistics

**2017-01-09 12:42:32****Jamie2483****439**View**1**Score**1**Answer- Tags: arcgis-desktop arcmap modelbuilder spatial-analyst zonal-statistics

#### 1 Answered Questions

### [SOLVED] Extract results from zonal statistics

**2016-04-22 13:48:39****Nausi****155**View**1**Score**1**Answer- Tags: qgis zonal-statistics

#### 1 Answered Questions

### [SOLVED] Resampling gives higher MEAN when using zonal statistics

**2015-11-30 22:52:26****Cicatrixx****154**View**2**Score**1**Answer- Tags: arcgis-desktop arcgis-10.1 statistics zonal-statistics resampling

## 0 comments