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albert-decatur/See-scene.sh

Last active August 29, 2015 14:19
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see landsat-api scene extents on geojson.io
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landsat-api_166036.geojson
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See-scene.sh
#!/bin/bash
# see Development Seed landsat-api scene extent on geojson.io
# example use: $0 LC81660362014196LGN00
scene=$1
# get scene metadata from devseed landsat-api
curl -s "https://api.developmentseed.org/landsat?search=${scene}" |\
# get corner coords
jq '.results[]|[.lowerLeftCornerLongitude,.lowerLeftCornerLatitude,"",.lowerRightCornerLongitude,.lowerRightCornerLatitude,"",.upperRightCornerLongitude,.upperRightCornerLatitude,"",.upperLeftCornerLongitude,.upperLeftCornerLatitude,"",.lowerLeftCornerLongitude,.lowerLeftCornerLatitude]|@csv' |\
# write as WKT
sed 's:\\::g;s:"::g;s:\(,\{2\}\):|:g;s:,: :g;s:|:,:g;s:^:POLYGON((:g;s:$:)):g' |\
# get geojson from WKT
wellknown |\
# send geojson to geojson.io
geojsonio
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see landsat-api scene extents on geojson.io

sources

  • landsat-api_166036.geojson comes from see-scene.sh, in this gist
  • example landsat scene downloaded with landsat-util

NB

The centroid from landsat-api does not quite agree with the polygon extent generated from API metadata.

Centroid calculated using PostGIS 2.1 w/ GEOS:

db=scratch
for i in *.geojson
do 
    # convert geojson to shp
    shp=$( basename $i .geojson ).shp
    ogr2ogr $shp $i
    # put shp in postgis
    shp2pgsql $shp |\
    psql $db
    # get centroid
    echo "COPY ( SELECT ST_ASTEXT(ST_CENTROID(geom)) AS wkt FROM \"$(basename $shp .shp)\" ) TO STDOUT" |\
    psql $db
done
source wkt
landsat-api POINT(48.5730475299341 34.6062500297351)
landsat-api metadata POINT(48.57291 34.61062)

This table shows distances in meters between these pairs of points.
This was made using a wkt_point_distances.sh, which given a list of WKT points, will output the distances between all non-duplicate pairs.

(Not needed in this case, but handy in general.)

distance_meters first_point second_point meaning
484.939851593 POINT(48.5730475299341 34.6062500297351) POINT(48.57291 34.61062) landsat-api poly centroid to landsat-api metadata centroid

This shows that there is a slight difference between the metadata centroid and the polygon centroid.
However, a quick check in QGIS makes it seem that the see-scene.sh polygon extent and the landsat-util download TIFs almost line up:

full extent
corner zoom - problem!

notes

Example going from 166036 in USGS shp to UTM39N coords:

select st_astext(st_transform(geom,32639)) from ( select st_geomfromtext('POLYGON ((47.336184808754908 34.000773145197954,47.336 34.0008,47.344247813251087 34.031334500589537,47.356167073033426 34.075461184083807,47.723740028525512 35.43626510683103,47.733319293907478 35.471728820126707,47.7439 35.5109,47.744165123892181 35.510861466860142,49.7461 35.2199,49.734986101711954 35.182108728143895,49.315052192874738 33.754181631894454,49.3035 33.7149,47.336184808754908 34.000773145197954))',4326) as geom ) a;

UTM zone can be determined by MTL.
Where can we get these before downloading the scene?

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