In this tutorial, we will learn how to read raster data from postgis table using python.
Python is a powerful tool for raster data analysis due to rich library ecosystem: Python has a large number of libraries specifically designed for geospatial data analysis, such as rasterio, rioxarray, gdal, geopandas, shapely, etc. These libraries provide a wide range of functions and tools to work with and analyze raster data.
Before reading raster data from postgis using python, we will set up conda environment and install required python GIS packages for this task. Make sure conda is installed on your system. Use following commands to create a conda environment and to install python libraries.
|
1 2 3 4 5 6 7 |
(base) geoknight@pop-os:~$conda create -n spatial-dev.guru python=3.10 (base) geoknight@pop-os:~$conda activate spatial-dev.guru (spatial-dev.guru) geoknight@pop-os:~$conda install -c conda-forge geocube (spatial-dev.guru) geoknight@pop-os:~$conda install -c conda-forge pygeos (spatial-dev.guru) geoknight@pop-os:~$conda install -c conda-forge rasterio (spatial-dev.guru) geoknight@pop-os:~$conda install -c conda-forge rioxarray (spatial-dev.guru) geoknight@pop-os:~$conda install -c conda-forge psycopg2 |
Step by step tutorial for reading a raster from a PostGIS table using Python:
- Import necessary modules:
- Configure the database connection:
- Define the table name:
- Read the raster from PostGIS:
- Load the raster in memory:
- Read the raster in memory:
The raster data is now stored in the raster_dataset object and can be manipulated and processed using rioxarray.
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 |
# Import necessary modules import psycopg2 from rasterio.io import MemoryFile import rioxarray as riox # DB Configuration dbname = "postgres" dbuser = "postgres" dbpass = "admin" dbhost = "localhost" dbport = "5432" # Connect to database using psycopg2 try: conn = psycopg2.connect(database=dbname, user=dbuser, password=dbpass, host=dbhost, port=dbport) curs = conn.cursor() print("Database connected successfully") except: print("Database not connected successfully") table_name = "sample_raster" # Read raster from postgis using ST_AsGDALRaster function curs.execute(f"""select ST_AsGDALRaster(st_union(rast), 'GTIFF') from {table_name}""") # Fetch result result = curs.fetchone() # Load raster in memory file using MemoryFile module of rasterio inMemoryRaster = MemoryFile(bytes(result[0])) # Read in memoery raster using rioxarray raster_dataset = riox.open_rasterio(inMemoryRaster) |
I hope this tutorial will create a good foundation for you. If you want tutorials on another GIS topic or you have any queries, please send an email at contact@spatial-dev.guru.
Pingback: Import rasters file to PostGIS database using raster2pgsql - Spatial Dev Guru