GDAL Cheat Sheet

• Compress imagery

as seen on http://blog.cleverelephant.ca/2015/02/geotiff-compression-for-dummies.html

    gdal_translate \
    -co COMPRESS=JPEG \
    -co PHOTOMETRIC=YCBCR \
    -co TILED=YES \
    5255C.tif 5255C_JPEG_YCBCR.tif


* If dealing with IR bands the recommended options are -co PHOTOMETRIC=RGB -co ALPHA=NO
source: https://lists.osgeo.org/pipermail/gdal-dev/2011-April/028455.html
With these 2 options you should get the 4th band defined as 'Undefined'. Otherwise you get a 4th band defined as Alpha.

Create overviews

    gdaladdo \
    --config COMPRESS_OVERVIEW JPEG \
    --config PHOTOMETRIC_OVERVIEW YCBCR \
    --config INTERLEAVE_OVERVIEW PIXEL \
    -r average \
    5255C_JPEG_YCBCR.tif \
    2 4 8 16

Compress a bunch of tifs...

    for FILE in *.tif
    do
    BASE=`basename $FILE .tif`
    NEWFILE=${BASE}_c.tif
    gdal_translate -b 1 -b 2 -b 3 -co COMPRESS=JPEG -co TILED=YES -co PHOTOMETRIC=YCBCR $FILE $NEWFILE
    done

• GDALWARP: *see below for using gdalwarp to merge tifs

    gdalwarp -s_srs EPSG:4326 -t_srs EPSG:27700 home_wgs84.bmp home_OSGB36.tif
  

Crops image based on shapefile select polygon using -cwhere

    gdalwarp -cutline shpfile.shp -cwhere "fieldname = 'fieldvalue'" -crop_to_cutline inimage.tif outimage.tif

Mask raster to cutline, use NO_GEOTRANSFORM for un-georeferenced images

    gdalwarp -to SRC_METHOD=NO_GEOTRANSFORM -to DST_METHOD=NO_GEOTRANSFORM -cutline cut_line.csv in.tif out.tif

            * Format of cut_line.csv
            id,WKT
            1,"POLYGON((9756 9321, 9756 360, 816 360, 816 9321, 9756 9321))"

            * options:
            -dstalpha to create an alpha band, masking nodata pixels
            -cblend <pixels> to feather eadges of imagery for a better seamless image
            -multi to multi-threaded processing

Subset with -te

    gdalwarp -te -7.35 48.48 3.79 59.51 merged_DEM.tif subset_DEM.tif

Mosaic with gdal

    gdalwarp --config GDAL_CACHEMAX 3000 -wm 3000 *.tif final_mosaic.tif

• Note that it is usually a good idea to "optimise" the resulting image with gdal_translate.

• gdal_translate

Compress tif

    gdal_translate -of GTiff -co COMPRESS=DEFLATE -co TILED=NO image1.tif image1_compressed.tif
    
    * optional argument to resize image -outsize 50% 50%
    *for GEOTIFF compression option -co NUM_THREADS=ALL_CPUS is available for better preformance

Convert Multi-band GeoTiff file to JPEG:

    gdal_translate -of JPEG 884084-utm.tif 884084-utm.jpg 

If GDAL complains about strange tags used in a tif file (http://www.gdal.org/frmt_gtiff.html)

    gdal_translate -co < PROFILE=BASELINE > or <PROFILE=GeoTIFF> input.tif output.tif

• gdal_contour:

   gdal_contour -a elev dem.tif contour.shp -i 10.0
  

• gdal_merge

Merge DEMs

    gdal_merge srtm_35_01.tif srtm_35_02.tif srtm_35_03.tif srtm_36_01.tif srtm_36_02.tif srtm_37_02.tif -o merged_DEM.tif

Merge Rasters:

    gdal_merge -o Theale_merged.tif Theale1_cal.bmp Theale2_cal.bmp Theale3_cal.bmp Theale4_cal.bmp

Copy all tifs to new location

    for %I in (image1.tif image2.tif image3.tif image4.tif) \
    do \
    copy %I test\folder\

• gdal2tiles - Create web map tiles

    gdal2tiles.py --zoom=11-15 --title=maptitle in.tif output_folder_name
  

• gdal polygonize

    gdal_polygonize Project_clip1.tif -f "ESRI Shapefile" vector.shp crit2 Value
  

• gdal calc source: http://www.gdal.org/gdal_calc.html

    Average 2 bands together
    gdal_calc.py -A input.tif -B input2.tif --outfile=result.tif --calc="(A+B)/2"
  

• SUBSET SHAPEFILE:

   ogr2ogr -spat -1.5 51 -0.5 52 -f "ESRI Shapefile" watersubset.shp waterways.shp
  

• MEND SHAPEFILE:

   ogr2ogr -skipfailures -f "ESRI Shapefile" mended.shp broken.shp
  

• KML to SHP:

   ogr2ogr -f "ESRI Shapefile" thames.shp thames.kml
  

• CONVERT SHAPE TO KML and change proj:

   ogr2ogr -f "KML" -s_srs "EPSG:27700" -t_srs  "EPSG:4326" rail.kml rail_OSGB36.shp
  

• Convert shp to kml w/ descriptions:

   ogr2ogr -f "KML" sample.kml sample.shp -dsco NameField=Field1 -dsco DescriptionField=field2
  

• Convert shp to kml - using "where" as query featuures:

   ogr2ogr -f "KML" -where "NBRHOOD='Telegraph Hill'" realtor_neighborhoods.kml realtor_neighborhoods.shp
  

• Convert shp to kml - using "select" to add specific attributes:

   ogr2ogr –SELECT “field1 field2 field3” -t_srs EPSG:4326 -f "KML" outPutFileName.kml inPutFileName.shp
  

• REPROJECT SHAPE FILE:

   ogr2ogr -s_srs "EPSG:4326" -t_srs "EPSG:27700" buildings_OS.shp buildings.shp
  

• Get information about a shapefile: (List Fields and type)

  ogrinfo -al ssurgo_geo.shp **This Lists ALL geometry which can be a pain
  
  ogrinfo -al -geom=NO ssurgo_geo.shp **Will not list millions of pages of geometry
  

• Extract all polygons from a SSURGO shapefile where the mapunit symbol is 'ScA':

  ogr2ogr -where "musym = 'ScA' " ssurgo_ScA.shp ssurgo_utm.shp 
  

• GPX files source: http://www.gdal.org/ogr/drv_gpx.html

  ogr2ogr --config GPX_SHORT_NAMES YES out input.gpx track_points
  

• GPX_SHORT_NAMES YES = converts long column names to shorter names to prevent non-unique names
• out = is the ouput location and folder
• track_points = the feature type you are converting/extracting from the file. Other options are: waypoints, route_points, routes, tracks. If nothing is specified then all are extracted. An empty shp file is created for those with no features.

• iterate over many files linux/unix (source: http://gothos.info/tag/gdal-ogr/)

  #!/bin/bash from Sherman (2008) Desktop GIS Mapping the Planet With Open Source Tools pp 243-44

  for shp in *.shp
  do
  echo “Processing $shp”
  ogr2ogr -f “ESRI Shapefile” -t_srs EPSG:4326 geo/$shp $shp
  done \

• Ogr with SQL

source: http://www.sarasafavi.com/intro-to-ogr-part-i-exploring-data.html

ogrinfo city_of_austin_parks.shp -sql "SELECT COUNT(*) FROM city_of_austin_parks"

* add '-so' for summary only 

SQL and look at only one feature

ogrinfo -q city_of_austin_parks.shp -sql "SELECT * FROM city_of_austin_parks" -fid 1

* '-q' = quiet

Same using all SQL

ogrinfo -q city_of_austin_parks.shp -sql "SELECT * FROM city_of_austin_parks WHERE fid IN (1,3)"

• Import into Postgis (from PostGIS Cookbook, 2014)

    ogr2ogr -f PostgreSQL -sql "SELECT ISO2, NAME AS country_name \
    FROM 'TM_WORLD_BORDERS-0.3' WHERE REGION=2" \
    -nlt MULTIPOLYGON \
    PG:"host=000.000.000.000 dbname='postgis_cookbook' user='me' password='mypassword'" \
    -nln africa_countries \
    -lco SCHEMA=chp01 \
    -lco GEOMETRY_NAME=the_geom \
    TM_WORLD_BORDERS-0.3.shp
  

• Export from Postgis (from PostGIS Cookbook, 2014)

    ogr2ogr -f GeoJSON -t_srs EPSG:4326 warmest_hs.geojson \
    PG:"host=000.000.000.000 dbname='postgis_cookbook' user='me' password='mypassword'" \
    -sql "SELECT f.the_geom as the_geom, f.bright_t31, ac.iso2, ac.country_name \
    FROM chp01.global_24h as f \
    JOIN chp01.africa_countries as ac \
    ON ST_Contains(ac.the_geom, ST_Transform(f.the_geom, 4326)) \
    ORDER BY f.bright_t31 DESC LIMIT 100"
  

• Using OGR with GNU Parallel

Source:http://blog.faraday.io/how-to-crunch-lots-of-geodata-in-parallel/

mkdir wgs84  
ls *.shp | parallel ogr2ogr -t_srs 'EPSG:4326' wgs84/{} {}