Classified Quantitative Symbology for Raster Datasets
Included in this tutorial
Symbology options
Classification methods
Changing the number of classes
Changing the color ramp
Examining the histogram (and using it to classify)
Software version in examples: ArcGIS Pro 3.0.0
Tutorial Data: The tutorial includes demonstration with sample data available here.
Credits: L. Meisterlin with Varisa Tanti (2022)
This tutorial demonstrates different symbology approaches for visualizing classified quantities with raster data.
For this demonstration we will use Tutorial Data, visualizing cell values by color according to different classification options.
Related tutorials:
The equivalent tutorial for unclassified values is Unclassified Quantitative Symbology for Rasters (”Stretched” Colors).
The tutorial that demonstrates different classification methods in ArcGIS Pro is Classifying Features by Quantitative Attribute Values.
Symbology Options
The Symbology panel will allow you to change the symbology type, the color scheme, and other classification options.
To edit the symbology of your raster layer, access the Symbology panel for your raster layer by right-clicking on the layer’s name in the Contents panel and choosing Symbology. (This is reviewed in the Unclassified Quantitative Symbology for Rasters (”Stretched” Colors) tutorial.)
To change your symbology to a classified quantitative symbology, click the Primary Symbology drop-down menu and select ‘Classify.’ As a reminder, classified quantitative symbology assigns a color for each class of values (which you can also define yourself).
open the Symbology panel and select “Classify” in the primary symbology drop-down menu
Classification Methods
The next drop-down option available is the ‘Method’ selection. Method options include: Natural Breaks (Jenks), Quantile, Equal Interval, Defined Interval, Manual Interval, Geometric Interval, and Standard Deviation. (Comparing classification methods is reviewed, using vector features as an example, in this tutorial.)
classification method options include Natural Breaks (Jenks), Quantile, Equal Interval, Defined Interval, Manual Interval, Geometric Interval, and Standard Deviation
Changing the Number of Classes
Next, decide how many classes you would like to use to represent your raster data and enter the number in ‘Classes.’ Below are examples of a raster map with 5 classes (top) and 12 classes (bottom).
example with five classes
example with twelve classes
Changing the Color Ramp
You can then change the color ramp in the Color scheme drop-down menu. (Note: formatting a custom color scheme is demonstrated in the tutorial on unclassified “stretched” raster symbology.)
the Color Scheme drop-down menu allows you to choose a pre-set color ramp (or format your own)
Examining the Histogram (and using it to classify)
Additionally, you can examine and change your classification method by accessing the Histogram tab.
Once you select a numerical value on the histogram, your classification method will automatically change to ‘Manual Interval.’ This method of manual entry will allow you to decide what classification intervals reflect your data best while seeing your data’s distribution in a rotated histogram.
the Histogram tab allows you to define manual intervals relative to the distribution of your dataset’s values