Checking if a GeoTIFF's Spatial Reference is Geodetic in Python

In python, how to check whether the spatial reference of a geotiff is geodetic or not?

To check whether the spatial reference of a GeoTIFF is geodetic (i.e., based on a geographic coordinate system) in Python, you can use libraries such as rasterio and pyproj. Here's a step-by-step guide on how to do this:

1. Install the necessary libraries: If you haven't already, you need to install rasterio and pyproj. You can do this using pip:

   pip install rasterio pyproj
   

2. Read the GeoTIFF and check the spatial reference: You can use rasterio to read the GeoTIFF file and pyproj to interpret the spatial reference system (SRS).

Here's a sample code to achieve this:

import rasterio
from pyproj import CRS

def is_geodetic(filepath):
    # Open the GeoTIFF file
    with rasterio.open(filepath) as dataset:
        # Get the CRS (Coordinate Reference System) of the dataset
        crs = dataset.crs
    
    # Convert the CRS to a pyproj CRS object
    crs_obj = CRS.from_wkt(crs.to_wkt())
    
    # Check if the CRS is geographic (geodetic)
    return crs_obj.is_geographic

# Example usage
filepath = 'path/to/your/geotiff.tif'
if is_geodetic(filepath):
    print("The spatial reference is geodetic.")
else:
    print("The spatial reference is not geodetic.")

Explanation:

1. Opening the GeoTIFF: The rasterio.open(filepath) function is used to open the GeoTIFF file.
2. Getting the CRS: The dataset.crs attribute provides the coordinate reference system of the dataset.
3. Converting to pyproj CRS: The CRS.from_wkt(crs.to_wkt()) function converts the CRS to a pyproj CRS object.
4. Checking if the CRS is geographic: The crs_obj.is_geographic attribute returns True if the CRS is geographic (geodetic), otherwise False.

This method ensures that you accurately determine whether the spatial reference of the GeoTIFF is geodetic.