Hi folks,
I’ve been looking at how to best prepare historical aerial photos for Geoserver. I had issues with exporting from ArcMap the individual aerial frames into Geotiffs – losing quality along the way. I’ve since worked that out.
I tried to apply Paul Ramsey’s GDAL steps to the exported files but didn’t get very far as these errors occurred:
C:\Program Files (x86)\GDAL>gdal_translate.exe -co COMPRESS=JPEG -co PHOTOMETRIC=YCBCR -co TILED=YES Aerial_1930.tif Aerial_1930-new.tif
Input file size is 3541, 3438
ERROR 1: MissingRequired:TIFF directory is missing required “StripOffsets” field
0ERROR 6: PHOTOMETRIC=YCBCR requires a source raster with only 3 bands (RGB)
The 1930 aerial frame is black and white (as you would expect for the era). So I think the 2nd error is related to that. I tried removing the PHOTOMETRIC option from the command but…
C:\Program Files (x86)\GDAL>gdal_translate.exe -co COMPRESS=JPEG -co TILED=YES Aerial_1930.tif Aerial_1930-new.tif
Input file size is 3541, 3438
ERROR 1: MissingRequired:TIFF directory is missing required “StripOffsets” field
0…10…20…30…40…50…60…70…80ERROR 1: JPEGSetupEncode:BitsPerSample 16 not allowed for JPEG
…ERROR 1: An error occured while writing a dirty block
ERROR 1: JPEGSetupEncode:BitsPerSample 16 not allowed for JPEG
I decided to turn to a more recent image:
C:\Program Files (x86)\GDAL>gdal_translate.exe -co COMPRESS=JPEG -co PHOTOMETRIC=YCBCR -co TILED=YES Aerial_1994.tif Aerial_1994-new.tif
Input file size is 5521, 5361
0…ERROR 1: JPEGSetupEncode:BitsPerSample 16 not allowed for JPEG
ERROR 1: WriteEncodedTile/Strip() failed.
ERROR 1: JPEGSetupEncode:BitsPerSample 16 not allowed for JPEG
ERROR 1: WriteEncodedTile/Strip() failed.
ERROR 1: An error occured while writing a dirty block
ERROR 1: JPEGSetupEncode:BitsPerSample 16 not allowed for JPEG
ERROR 1: WriteEncodedTile/Strip() failed.
ERROR 1: JPEGSetupEncode:BitsPerSample 16 not allowed for JPEG
ERROR 1: WriteEncodedTile/Strip() failed.
ERROR 1: JPEGSetupEncode:BitsPerSample 16 not allowed for JPEG
ERROR 1: WriteEncodedTile/Strip() failed.
This is the first workflow I’ve tried and I’m open to any that others on the list might use when preparing Geotiff for Geoserver.
Many thanks and happy Friday (in Australia),
Neil
···
From: Jody Garnett <jody.garnett@…84…>
Sent: Wednesday, 21 July 2021 4:09 PM
To: Neil Saunders <neil.saunders@…9733…>
Cc: geoserver-users@lists.sourceforge.net
Subject: Re: [Geoserver-users] Getting the best results with Raster
Neil:
Can you describe more in what way the quality is lacking? Is it distorted, or pixelated, or what? Did you do any data prep to your geotiff, say introduce an overview? If so what sampling technique did you use?
What does “gdalinfo” return for your image?
Some general guidance from Paul Ramsey is here https://blog.cleverelephant.ca/2015/02/geotiff-compression-for-dummies.html
–
Jody Garnett
On Tue, 20 Jul 2021 at 19:00, Neil Saunders <neil.saunders@…9733…> wrote:
Hi folks,
Apologies if this is a basic question – I’m fairly new to GIS data.
I’m using Geoserver 2.18.2 to host historical aerial clips and exporting the rasters with Arc Map 10.6 to Geotiff with a 500m buffer of a property. However I’m finding the quality of the image in Geoserver does not match the quality in Arc Map when zoomed in.
I’ve tried exporting at different DPI but find 300 or above has no discernible improvement. I’m not using any compression when creating the TIFF and using GeoTIFF Tags. I’ve read about resampling and how it can alter the image quality but not sure if that’s it.
Assuming this is not a new challenge, I’m curious what steps others have taken to get raster clips into Geoserver in a way that doesn’t compromise the image quality? I’m using the most detailed historical aerial photography as the use case requires inspection of features at the street level. Any help gratefully received!
Kind Regards,
Neil Saunders
Business Consultant
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Thanks to others for suggestions - the primary issue appears to actually be related to the initial export from Arc Map 10.6 e.g. when the GeoTIFF is first created. The issue is a loss of quality (visually in pixellation) in the TIFF when working at a large scale (zoomed in). I’ve been exporting using Arc’s “300 dpi” setting with no compression. This might be off topic now but I wondered if anyone had experience / best practice when preparing GeoTIFF clips from Arc Map? Or perhaps there is a better tool like gdal or QGIS (I haven’t used these before). I’m working with large GeoTIFF “aerial frames” (800Mb) and satellite WMS layers and wish to export clipped GeoTIFF to specific buffers (500m) automatically.