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I am trying to make a map depicting forests in Japan using TIF files downloaded here. I want to reproject the data, clip it, and use it to style a hillshade map. When I attempt to reproject it however, it takes a very long time, and the output file is huge! The original TIF is quite big at 411.6MB, however the reprojected file clocks in at 1.75GB, and this is only one of roughly 8 TIF files I eventually want to use.

Why is this happening? Is there some fundamental step that I'm missing? If there's any other information I can provide, please let me know.

Data for the original file:

Name    1_Hansen_GFC-2018-v1.6_treecover2000_50N_130E
CRS EPSG:4326 - WGS 84 - Geographic
Extent  130.0000000000000000,40.0000000000000000 : 140.0000000000000000,50.0000000000000000
Unit    degrees
Width   40000
Height  40000
Data type   Byte - Eight bit unsigned integer
GDAL Driver Description GTiff
GDAL Driver Metadata    GeoTIFF
Dataset Description /Users/benleamon/Documents/Infographics/projects/japan-forests/data/forests/1_Hansen_GFC-2018-v1.6_treecover2000_50N_130E.tif
Compression LZW
Band 1  
More information    
AREA_OR_POINT=Area
Dimensions  X: 40000 Y: 40000 Bands: 1
Origin  130,50
Pixel Size  0.0002500000000000000052,-0.0002500000000000000052

And then here is the data for the output file:

Name    reproj-full-forests
CRS EPSG:6691 - JGD2011 / UTM zone 54N - Projected
Extent  -439944.6735999999800697,4428235.8196999998763204 : 428345.5341999999945983,5596865.5570999998599291
Unit    meters
Width   36028
Height  48490
Data type   Byte - Eight bit unsigned integer
GDAL Driver Description GTiff
GDAL Driver Metadata    GeoTIFF
Dataset Description /Users/benleamon/Documents/Infographics/projects/japan-forests/output/reproj-full-forests.tif
Compression 
Band 1  
More information    
AREA_OR_POINT=Area
Dimensions  X: 36028 Y: 48490 Bands: 1
Origin  -439945,5.59687e+06
Pixel Size  24.10042766181858553,-24.10042766343575948

My system is a macbook air with 4GB ram, which I know is far less than ideal, hence my plan to process and clip each tile independently before combining on the final map.

1 Answer 1

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Your first file is compressed with LZW and the output is not so it is bigger. Though for reference 1.7Gb is not huge!

When you save your new file select the High Compression profile in the Create Options (if you use save as) or Advanced Parameters (if you use Warp (Reproject):

enter image description here

3
  • Thank you so much! I noticed that you're doing this via save-as, is it better to change the projection that way than by using the warp tool?
    – Ben
    Mar 21, 2020 at 11:10
  • either will give the result you want (and both include a high compression option for the output)
    – Ian Turton
    Mar 21, 2020 at 11:41
  • 1
    You have more options while using command shell. More info here: blog.cleverelephant.ca/2015/02/…
    – christoph
    Mar 21, 2020 at 15:46

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