Downloads GFloat National Elevation Dataset data from USGS, converts to GTiff, then merges to a single tif. Expects a file 'ned_links.html' in the same directory that has the HTML contents of the email from USGS containing the download links for the GFloat zip files. Depends on BeautifulSoup and gdal; expects to be on a unix-y system.

ned_fetcher.py

#!/usr/bin/env python

from bs4 import BeautifulSoup
import requests, os, subprocess
from time import sleep

download_dir = os.getcwd()

soup = BeautifulSoup(open('ned_links.html','rb'))
of = open('just_ned_links.txt', 'wb')

for link in soup.find_all('a'):
  of.write(link.get('href') + '\n')
  
of.close()

inf = open('just_ned_links.txt', 'rb')
for ln in inf:
  url = ln.strip('\n')
  got_fname = url.find('FNAME=')
  fname = os.path.join(download_dir, url[got_fname + 6:url.find('&', got_fname)])
  r = requests.get(url)
  
  if not r.ok:
    print('failed downloading ' + fname + ' from ' + url)
    print(str(r.status_code) + ": " + r.reason + '\n\n')
    break # bail
  else:
    print('got ' + fname + '...')
    of = open(fname, 'wb')
    of.write(r.content)
    of.close()
  
inf.close()

extract_dir = os.path.join(download_dir, 'extracted')
tif_dir = os.path.join(download_dir, 'tifs')
if not os.path.isdir(extract_dir):
  os.mkdir(extract_dir)
if not os.path.isdir(tif_dir):
  os.mkdir(tif_dir)

for p, d, fs in os.walk(download_dir):
  for f in fs:
    if f.endswith('.zip'):
      print('converting ' + f + '...')
      f_strip = f[:-4]
      subprocess.check_output(['unzip', os.path.join(p, f), 
        '-d', extract_dir])
      
      # convert GFloat downloads to GTiff
      # gdal_translate -co COMPRESS=LZW -co PREDICTOR=3 -co TFW=YES 
      # -of GTiff floatn39w075_1.flt 'test.tif'

      subprocess.check_output(['gdal_translate', '-co', 'COMPRESS=LZW', '-co',
        'PREDICTOR=3', '-co', 'TFW=YES', '-of', 'GTiff', 
        os.path.join(os.path.join(extract_dir, f_strip), 'float' + f_strip + '_1.flt'),
        os.path.join(tif_dir, f_strip + '.tif')])
        
# afterwards, merge with:
# gdal_merge.py -o merged_elevation.tif *.tif
print("finished converting.  merging tifs...")
sleep(3) 

subprocess.check_output(['gdal_merge.py', '-o', 
  os.path.join(tif_dir, 'merged_elevation.tif'), os.path.join(tif_dir, '*.tif')])
print('Merged tif is at: ' + os.path.join(tif_dir, 'merged_elevation.tif'))

# remove directory of extracted zip files
suprocess.call(['rm', '-r', extract_dir])

print('done!')