geotiff-to-geojson.sh

#!/bin/bash
#
# Requires:
#   - gdal_sieve.py
#   - ogr2ogr (GDAL)
#		- topojson (node.js)

# Grab the relative directory for source file.
SRC_DIR=`dirname $0`

# Which raster to compress.
ORG_FILE="$SRC_DIR/raw/anthromes/$1/anthro2_a$1.tif"

# Final output file.
OUTPUT_FILE="$SRC_DIR/processed/anthrome-$1.json"

echo "Processing $ORG_FILE."

# Where to output the new file.
TMP_DIR=./tmp

# The amount of times the file should be passed over.
ITERATIONS=3

# Threshold for each iteration.
THRESHOLD=40

# TopoJSON area threshold for simplification.
TOPO_COMPRESSION=0.000005

# Setup internal vars.
_CUR=$THRESHOLD
_COMPRESSION=$(($ITERATIONS * $THRESHOLD))

rm -rf $TMP_DIR
mkdir -p $TMP_DIR

# Start sieve passes.
gdal_sieve.py -st $THRESHOLD -4 $ORG_FILE $TMP_DIR/output-"$THRESHOLD".tiff

while [ $_CUR -le $_COMPRESSION ]; do
	let _PREV=$_CUR
	let _CUR=$_CUR+$THRESHOLD
	echo "Compressing output-$_PREV.tiff into $_CUR.tiff"
	gdal_sieve.py -st $THRESHOLD -4 "$TMP_DIR/output-$_PREV.tiff" \
		"$TMP_DIR/output-$_CUR.tiff"
	rm "$TMP_DIR/output-$_PREV.tiff"
done

# Raster to vector.
gdal_polygonize.py $TMP_DIR/output-"$_CUR".tiff \
	-f "ESRI Shapefile" $TMP_DIR vector n

# Change shapefile to geojson without the 0 layer, which is water.
ogr2ogr -f "GeoJSON" -where "n != 0" "$TMP_DIR/geojson.json" $TMP_DIR/vector.shp

# Convert to compressed TopoJSON.
topojson -o $OUTPUT_FILE \
	--no-stitch-poles \
	-s $TOPO_COMPRESSION \
	-p -- "$TMP_DIR/geojson.json"

# Clean up.
rm -rf $TMP_DIR

Thank you for this code. Would you create one that converts geojson to geotiff?

The topojson on line 58 does not work anymore. Change it to geo2topo
You can get the executable using npm
npm i -g topojson