Reclassify (Classification)
Usage
Assign classes by cell value ranges: first generate classification intervals from raster statistics, then map a continuous raster, such as elevation, slope, concentration, or risk values, to classes or weights by interval, for example 0-10 -> 1 and 10-20 -> 2.
This tool is suitable for continuous or near-continuous rasters. It does not change the raster extent, cell size, or coordinate system. It only replaces cell values based on whether they fall within the specified intervals.
The Value range mapping dictionary in the interface is not limited to manually entered intervals. The tool automatically generates an interval table based on the selected classification method. You can then adjust class breaks or change the new value assigned to each interval.
Inputs And Outputs
- Input: A raster file. Multiband rasters are supported, and a specific band can be selected.
- Output: A reclassified raster file. The spatial reference, extent, and resolution are the same as the input.
If the input is a multiband raster, the tool processes the band specified by Band selection. If no band is selected, or band 1 is selected, the first band is processed.
Parameters
| Parameter | Description |
|---|---|
| Input raster file | The source raster to classify by range. Suitable for continuous-value or classified-value rasters such as elevation, slope, index, concentration, or risk values. |
| Band selection | The 1-based index of the band to process. If not set, the first band is used by default. |
| Classification method | The method used to generate reclassification intervals. Equal interval, quantile, natural breaks, and standard deviation classification are supported. |
| Number of classes | Used for equal interval, quantile, and natural breaks classification. It specifies how many class intervals to generate. |
| Interval size | Used for standard deviation classification. The interval can be 1, 1/2, 1/3, or 1/4 standard deviation. |
| Value range mapping dictionary | The classification rule table. The interface automatically generates intervals based on the classification method. Each row contains a range and a new value. It can also be understood as minimum-maximum-assigned value; for example, 0-10-1 assigns cells within the interval to 1. |
| Output raster file | The output result path and file name. The output raster preserves the spatial reference, extent, and resolution of the input raster. |
Classification Methods
| Classification method | Description | Use case |
|---|---|---|
| Equal interval | Divides the numeric range from minimum to maximum into equal intervals. | Use when values are relatively evenly distributed or when fixed intervals are required. |
| Quantile | Attempts to place a similar number of cells in each class. | Use when each class should contain a relatively balanced number of cells. |
| Natural breaks | Generates breaks based on natural clusters and gaps in the data distribution. | Use when values are unevenly distributed or show clear clusters or jumps. |
| Standard deviation | Classifies values based on the mean and standard deviation. | Use when you need to show deviation from the average level. |
Steps
- Start the tool: Open the Geoprocessing Toolbox > go to Raster Tools > Raster Processing > Reclassify > start the Reclassify (Classification) tool pane.
- Select the input raster: In Input raster file, select the raster whose values need to be classified and assigned.
- Select the processing band: If the input raster contains multiple bands, specify the band to reclassify in Band selection. If it is not set, band 1 is processed.
- Select the classification method: In Classification method, select equal interval, quantile, natural breaks, or standard deviation, and set Number of classes or Interval size.
- Confirm intervals and new values: The tool automatically generates the Value range mapping dictionary. Review each interval range and modify the New value column based on your requirements.
- Set the output: Specify Output raster file, and confirm that the output path, format, and naming meet downstream requirements.
- Run and review the result: Click Run to generate the result. After completion, check whether the classified values, unclassified cells, and boundary intervals meet expectations.
Notes
- Interval evaluation rules: for all rules except the last one, intervals are evaluated as
>= minimumand< maximum; the last rule is evaluated as>= minimumand<= maximum. - Avoid overlapping intervals. If intervals overlap, later rules may overwrite earlier results and cause unexpected output.
- Review intervals in ascending order to help identify gaps or overlaps.
- Cell values that do not fall within any interval remain unchanged. Only cells within intervals are assigned new values.
- Output values should be compatible with the target raster data type. If output values contain decimals, the save format or advanced output settings should support floating-point values.
Example
- Slope classification. Units depend on your input raster. The following rules can be automatically generated by a classification method and then modified, or adjusted manually:
0-5-1
5-15-2
15-90-3
In these rules, 0 <= cell value < 5 is assigned 1, 5 <= cell value < 15 is assigned 2, and the final interval 15 <= cell value <= 90 is assigned 3.