Search Raster Files from Folder that Have Same Spatial Coordinates Using Python

Question

I have approximately 700 raster files in a single folder and I need to find files that have the same spatial extent and copy to a different folder. The raster files measure daily snow cover and therefore have the exact same spatial extent.

Answer 1

One possible solution using GDAL.

The first trick is get a list of rasters into Python. For argument's sake we'll assume they are all TIFF files, meaning we can use glob to parse the directory:

import glob
raster_list = glob.glob("path_to_folder/*.tif")

I'm going to assume that you don't know what the size is, so you want different folders for each set of rasters with the same size. We'll use the GDAL's RasterXSize, RasterYSize dataset attributes and the GetGeoTransform() method to compare Rasters (see Week 4 slides here for examples of how these work), storing the results in a dictionary.

import shutil
import os
from osgeo import gdal
gdal.AllRegister() #Registers data formats

i = 0 #We'll start with folder zero
extents = {}

for r in raster_list:
    ds = gdal.Open(r, GA_ReadOnly) #GA_ReadOnly is the GDAL Access level
    gt = ds.GetGeoTransform()
    top_left_x = gt[0]
    top_left_y = gt[3]
    bottom_right_x = top_left_x + ds.RasterXSize * gt[1] #x cell size
    bottom_right_y = top_left_y - ds.RasterYSize * gt[4] #y cell size
    #we use a tuple of the extent to store the destination folder
    if (top_left_x, top_left_y, bottom_right_x, bottom_right_y) not in extents:
        f_name = "extent" + str(i) #new folder name
        i += 1
        os.mkdir(f_name)
        extents[(top_left_x, top_left_y, bottom_right_x, bottom_right_y)] = f_name
    #regardless, we copy the file
    shutil.copyfile(r, extents[(top_left_x, top_left_y, bottom_right_x, bottom_right_y)])

Note you could perform an almost identical operation with arcpy.ListDatasets("*", "Raster") and arcpy.Describe(raster).extent if you have ArcGIS (see here and here for docs).