To convert a float raster to polygon features in ArcGIS Pro, you primarily use the Raster to Polygon geoprocessing tool found within the Conversion toolbox.
Converting Raster to Polygon in ArcGIS Pro
The Raster to Polygon tool is a standard method in ArcGIS Pro for converting raster datasets into polygon features. It works by grouping adjacent raster cells that have the same value and creating polygon features from these groups. The process, as outlined in the reference, involves loading your raster, accessing the tool, setting parameters, and running it.
Step-by-Step Conversion Process
Here's a breakdown of the process using the Raster to Polygon tool:
- Load the Raster Layer: Begin by loading your float raster layer into a map in ArcGIS Pro. This makes the layer available for selection within geoprocessing tools.
- Access the Tool: Navigate to the Conversion toolbox in the Geoprocessing pane. Within this toolbox, you will find the From Raster toolset, which contains the Raster to Polygon tool. Alternatively, you can use the search bar in the Geoprocessing pane to find the tool by name.
- Configure Tool Parameters: Open the Raster to Polygon tool.
- Select your input float raster layer from the dropdown list for the Input Raster parameter.
- Specify the location and name for the new output polygon feature class in the Output Polygon Features parameter.
- Choose the Field that will be used to get values from the input raster. For integer rasters, this is typically 'Value'. For float rasters, you might need to select a specific field if one exists or consider preprocessing steps (see below).
- Configure other optional parameters like Simplify polygons. Simplifying polygons can reduce feature complexity but might generalize boundaries. Deselecting this option (
SIMPLIFY = FALSE) creates polygons with stair-step boundaries that perfectly match the raster cell edges.
- Run the Tool: Once all parameters are set, click the Run button. The tool will process the raster and create the new polygon feature class.
Important Considerations for Float Rasters
While the Raster to Polygon tool is used, converting float rasters directly presents a unique challenge. The tool works by grouping cells with identical values. Float rasters often have continuous, unique values for almost every cell.
- Lack of Identical Values: If your float raster has unique values across most cells, converting it directly will likely result in a multitude of very small polygons, potentially one for almost every cell.
- Need for Reclassification or Conversion: To get meaningful polygons from a float raster, you typically need to preprocess it to create groups of cells with the same value. This is often done through:
- Reclassification: Using tools like Reclassify to group ranges of float values into a smaller set of integer classes. For example, group elevation values (float) into ranges like "Low", "Medium", "High" (integers).
- Integer Conversion: Using the Int tool to convert the float values to integers. This truncates or rounds values, creating identical integer values where the original float values were similar. This is useful if the integer part of the float value represents a meaningful category.
Therefore, for most practical applications involving float rasters, the Raster to Polygon workflow will involve an intermediate step of converting the float raster to an integer raster (or reclassifying it) before using the Raster to Polygon tool.
Accessing the Raster to Polygon Tool
You can easily find the Raster to Polygon tool within ArcGIS Pro:
- Geoprocessing Pane: Open the Geoprocessing pane (accessible via the Analysis tab or the View tab). Expand the Toolboxes list. Navigate to Conversion Tools > From Raster > Raster to Polygon.
- Search: Use the search bar at the top of the Geoprocessing pane and type "Raster to Polygon". Select the tool from the results.
Tool Parameters Overview
Key parameters you will encounter in the Raster to Polygon tool include:
| Parameter | Description |
|---|---|
| Input Raster | The raster layer (your float raster or a preprocessed integer version). |
| Output Polygon Features | The location and name for the new polygon feature class that will be created. |
| Field | Determines which raster cell attribute (e.g., Value, Count) becomes the polygon attribute. Use 'Value' for standard conversions. |
| Simplify polygons | Controls whether the output polygons are simplified or follow cell boundaries. (Recommended: SIMPLIFY = FALSE for direct raster-to-vector conversion). |
Practical Tips
- Understand Your Data: Know what the float values in your raster represent and how you want to group them into polygons. This will dictate whether you need to reclassify the raster first.
- Reclassify Meaningfully: If reclassifying, choose appropriate ranges based on your data's distribution and the phenomena you are mapping.
- Output Location: Always specify a geodatabase or feature dataset as the output location for the polygon feature class for better data management.
In summary, while the core tool for converting a raster to polygons in ArcGIS Pro is Raster to Polygon, converting a float raster typically requires preprocessing steps to create meaningful groups of identical cell values before applying the tool.
