First-order texture
From AWF-Wiki
(Difference between revisions)
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− | Standard deviation or | + | Local statistical moments (Mean, Variance, Standard deviation, Skewness, Kurtosis) calculated on every pixel in the selected channel of the input image, over a specified neighborhood are called ''first-order'' textures. |
− | a pixel | + | * In the search engine of the Processing Toolbox, type '''Local Statistic''' and select '''Local Statistic Extraction''' under Feature Extraction of the Orfeo Toolbox. |
+ | * Under the Parameters tab, select a single band or a multiband file as input layer. | ||
+ | * In case of a multiband file select the band number. | ||
+ | * Select an integer number as '''Neighborhood size''' in pixels. | ||
+ | [[File:Qgis_texture_Localstatistics.png|400px] | ||
+ | The output image is a multiband with 4 statistical moments per band in the exact order: | ||
+ | # Mean | ||
+ | # Variance | ||
+ | # Skewness | ||
+ | # Kurtosis | ||
+ | The standard deviation of gray levels in a region in the neighborhood of a pixel can be calculated by a GRASS GIS modul: | ||
* In the search engine of the Processing Toolbox, type '''neighbors''' and select '''r.neighbors''' under Raster of GRASS GIS 7 commands. | * In the search engine of the Processing Toolbox, type '''neighbors''' and select '''r.neighbors''' under Raster of GRASS GIS 7 commands. | ||
* Under the Parameters tab, select a single band file as input layer. | * Under the Parameters tab, select a single band file as input layer. | ||
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{| class="wikitable" | {| class="wikitable" | ||
|style="border: 0pt" | [[file:Qgis_campus_synthesis.png|thumb|left|400px|'''Figure A:''' Input image: Sentinel-2 synthesis image based on 4 10m bands, (University Göttingen Campus North)]] | |style="border: 0pt" | [[file:Qgis_campus_synthesis.png|thumb|left|400px|'''Figure A:''' Input image: Sentinel-2 synthesis image based on 4 10m bands, (University Göttingen Campus North)]] | ||
− | |style="border: 0pt" | [[file: | + | |style="border: 0pt" | [[file:Qgis_campus_firstorder_texture.png|thumb|center|400px|'''Figure B:''' Output image: First-order textures of Sentinel-2 synthesis image RGB=Skewness, Variance, Mean (University Göttingen Campus North)]] |
+ | |style="border: 0pt" | [[file:Qgis_campus_stdev.png|thumb|center|400px|'''Figure C:''' Output image: Standard deviation texture of Sentinel-2 synthesis image (University Göttingen Campus North)]] | ||
|} | |} | ||
[[category:Spatial Filtering]] | [[category:Spatial Filtering]] |
Revision as of 16:45, 20 November 2017
Local statistical moments (Mean, Variance, Standard deviation, Skewness, Kurtosis) calculated on every pixel in the selected channel of the input image, over a specified neighborhood are called first-order textures.
- In the search engine of the Processing Toolbox, type Local Statistic and select Local Statistic Extraction under Feature Extraction of the Orfeo Toolbox.
- Under the Parameters tab, select a single band or a multiband file as input layer.
- In case of a multiband file select the band number.
- Select an integer number as Neighborhood size in pixels.
[[File:Qgis_texture_Localstatistics.png|400px]
The output image is a multiband with 4 statistical moments per band in the exact order:
- Mean
- Variance
- Skewness
- Kurtosis
The standard deviation of gray levels in a region in the neighborhood of a pixel can be calculated by a GRASS GIS modul:
- In the search engine of the Processing Toolbox, type neighbors and select r.neighbors under Raster of GRASS GIS 7 commands.
- Under the Parameters tab, select a single band file as input layer.
- Select stddev from the drop-down list Neighborhood operation.
- Select an odd integer number as Neighborhood size in pixels.
- Tick Use circular neighborhood.