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とらりもん - GeoTiffのカラーテーブルを変更する Diff

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2017/04/26 Jin Katagi
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! gdaldemコマンドを使う場合 / use gdaldem command.
多分これが一番お手軽。

I think this way is the most easy.

vim color_table.txt # 4 column is alpha channel?
0. 255 255 255 0
1. 255 0 0 0
2. 180 0 0 0

gdaldem color-relief -of GTiff input.tif color_table.txt output.tif


*[[参考|https://gis.stackexchange.com/questions/130199/changing-color-of-raster-images-based-on-their-data-values-gdal]]

! GRASS GISのr.colorsコマンドを使い場合 / use GRASS GIS command.
一旦GRASSの環境にtiffを読み込む必用がある。GRASS 6.X系と7.X系でコマンドの使い方が若干違う。


vim color_table.txt
0  255:255:255
1  255 0 0
2  180 0 0

grass # start GRASS envirionment
r.in.gdal input=input.tif output=input # import tif to GRASS
g.region rast=input # set region to the image
r.colros # change color, 書きかけ
cat color_table.txt | r.colors map=input rules=- # For GRASS 7.X.
# cat color_table.txt | r.colors map=input color=rules # For GRASS 6.X
r.out.gdal input=input output=input_change_color.tif # save as GeoTiff

*[[参考|https://grass.osgeo.org/grass72/manuals/r.colors.html]]

! gdalbuildvrtコマンドを使う場合 / use gdalbuildvrt command.
gdalbuildvrtでvrtを書き出し、直接vrtを変更して、tiffに戻す。

*[[参考|https://gis.stackexchange.com/questions/130199/changing-color-of-raster-images-based-on-their-data-values-gdal]]