GIS MCP Server

Instructions

Implementation Reference

• src/gis_mcp/rasterio_functions.py:1092-1172 (handler)

  The core handler function for the 'raster_algebra' tool. It takes two raster paths, a band index, an operation ('add' or 'subtract'), and a destination path. Automatically aligns the rasters if CRS, transform, or shape differ, performs the operation on the specified bands, and writes the result to the output file.
  def raster_algebra( raster1: str, raster2: str, band_index: int, operation: str, # User selects "add" or "subtract" destination: str ) -> Dict[str, Any]: """ Perform algebraic operations (addition or subtraction) on two raster bands, handling alignment issues automatically. Parameters: - raster1: Path to the first raster (.tif). - raster2: Path to the second raster (.tif). - band_index: Index of the band to process (1-based index). - operation: Either "add" or "subtract" to specify the calculation. - destination: Path to save the result as a new raster. The function aligns rasters if needed, applies the selected operation, and saves the result. """ try: import rasterio import numpy as np from rasterio.warp import reproject, calculate_default_transform, Resampling # Expand file paths r1 = os.path.expanduser(raster1.replace("`", "")) r2 = os.path.expanduser(raster2.replace("`", "")) dst = os.path.expanduser(destination.replace("`", "")) # Open the raster files with rasterio.open(r1) as src1, rasterio.open(r2) as src2: # Ensure alignment of rasters if src1.crs != src2.crs or src1.transform != src2.transform or src1.shape != src2.shape: transform, width, height = calculate_default_transform( src2.crs, src1.crs, src2.width, src2.height, *src2.bounds ) aligned_data = np.zeros((height, width), dtype="float32") reproject( source=src2.read(band_index), destination=aligned_data, src_transform=src2.transform, src_crs=src2.crs, dst_transform=transform, dst_crs=src1.crs, resampling=Resampling.bilinear ) band2 = aligned_data else: band2 = src2.read(band_index).astype("float32") band1 = src1.read(band_index).astype("float32") # Perform the selected operation if operation.lower() == "add": result = band1 + band2 elif operation.lower() == "subtract": result = band1 - band2 else: raise ValueError("Invalid operation. Use 'add' or 'subtract'.") # Prepare output raster metadata profile = src1.profile.copy() profile.update(dtype="float32", count=1) # Ensure the output directory exists os.makedirs(os.path.dirname(dst) or ".", exist_ok=True) # Save the result to a new raster file with rasterio.open(dst, "w", **profile) as dstfile: dstfile.write(result, 1) return { "status": "success", "destination": dst, "message": f"Raster operation '{operation}' completed and saved." } except Exception as e: raise ValueError(f"Failed to perform raster operation: {e}")
• src/gis_mcp/rasterio_functions.py:11-35 (registration)

  Resource endpoint listing 'raster_algebra' as an available rasterio operation, which serves as a discovery mechanism for the tool.
  @gis_mcp.resource("gis://operation/rasterio") def get_rasterio_operations() -> Dict[str, List[str]]: """List available rasterio operations.""" return { "operations": [ "metadata_raster", "get_raster_crs", "clip_raster_with_shapefile", "resample_raster", "reproject_raster", "weighted_band_sum", "concat_bands", "raster_algebra", "compute_ndvi", "raster_histogram", "tile_raster", "raster_band_statistics", "extract_band", "zonal_statistics", "reclassify_raster", "focal_statistics", "hillshade", "write_raster" ] }
• src/gis_mcp/main.py:66-72 (registration)

  Imports the rasterio_functions module in the main entry point, which executes the decorators to register the 'raster_algebra' tool with the MCP server.
  from . import ( geopandas_functions, shapely_functions, rasterio_functions, pyproj_functions, pysal_functions, )