When managing large volumes of high-resolution satellite imagery (e.g., 1:10,000 scale sheets), visualizing coverage gaps becomes challenging due to performance limitations in ArcMap. This script automates the creation of vector polygons representing raster extents for efficient gap analysis.

ArcPy Vectorized Raster Extents
Visualization: Red outlines = actual coverage, Green polygons = generated extents


Detail showing alignment accuracy

Implementation Code

# -*- coding: utf-8 -*-
import os
import time
import arcpy

def create_directory(path):
    """Ensure directory exists, create if missing"""
    if os.path.isdir(path):
        if not os.path.exists(path):
            os.makedirs(path)
    else:
        parent_dir = os.path.dirname(path)
        if not os.path.exists(parent_dir):
            os.makedirs(parent_dir)

if __name__ == '__main__':
    # Configure input/output
    raster_directory = r'F:\gisData\data0929\refY202410072'
    output_shapefile = os.path.join(raster_directory, 'shp', 'RasterExtent.shp')
    
    start_time = time.time()
    arcpy.env.workspace = raster_directory
    raster_list = arcpy.ListRasters()
    
    if not raster_list:
        raise IOError("Error: No raster files found!")
    
    # Prepare output feature class
    if arcpy.Exists(output_shapefile):
        arcpy.Delete_management(output_shapefile)
    
    create_directory(output_shapefile)
    output_fc = arcpy.CreateFeatureclass_management(
        os.path.dirname(output_shapefile), 
        "RasterExtent.shp", 
        "POLYGON"
    )
    arcpy.AddField_management(output_fc, "RasterName", "TEXT", 50)
    
    # Process rasters
    with arcpy.da.InsertCursor(output_fc, ["SHAPE@", "RasterName"]) as cursor:
        for raster_file in raster_list:
            raster = arcpy.Raster(raster_file)
            extent = raster.extent
            
            # Construct polygon from extent
            polygon_points = arcpy.Array([
                arcpy.Point(extent.XMin, extent.YMin),  # LL
                arcpy.Point(extent.XMin, extent.YMax),  # UL
                arcpy.Point(extent.XMax, extent.YMax),  # UR
                arcpy.Point(extent.XMax, extent.YMin),  # LR
                arcpy.Point(extent.XMin, extent.YMin)   # Close ring
            ])
            
            cursor.insertRow([arcpy.Polygon(polygon_points), raster_file])
    
    # Performance metrics
    elapsed = time.time() - start_time
    print(f"Process completed in: {elapsed:.2f} seconds")

Key Workflow

  1. Input Configuration: Specify directory containing raster files
  2. Output Handling: Automatically creates output shapefile

  3. Extent Extraction:

    • Retrieves XMin/YMin/XMax/YMax for each raster
    • Constructs rectangular polygons from corner coordinates
  4. Attribute Storage: Preserves original raster filenames

Advantages

  • Eliminates manual extent digitization
  • Enables efficient coverage gap analysis
  • Handles thousands of rasters in batch processing
  • Integrates with standard ArcGIS workflows
Note: Requires ArcGIS Desktop with Spatial Analyst extension. Execution time scales linearly with raster count.