GeoTools

Problem GeoTiff Reported

Details

  • Type: Bug Bug
  • Status: Closed Closed
  • Priority: Major Major
  • Resolution: Won't Fix
  • Affects Version/s: 2.6.5
  • Fix Version/s: None
  • Component/s: geotiff
  • Labels:
    None

Description

We have a problem geotiff reported; the file is available as an attachment to the udig bug report.

The geotiff consists of two images:

  • A "scanned map" GeoTIFF, which is color-coded with 256 colors (or less) on 1 band.
  • A "transparency mask," always present in the file. It identifies the padded pixels wich have the color code "0" in the main picture.

The TIFF tag "SampleFormat" is set to "1" (default) to specify an encoding on an unsigned integer value.

I do not know the library used to generate this file. It is likely a library derived from GDAL.

The 'data' part of a ortho-image product type is composed of a single file GeoTIFF. This file may contain two sub-files (as defined in the "subfile" TIFF specification) and thus two IFD :
one for the image itself and one for the possible transparency mask. The image itself is always described by the first IFD of the file.
The transparency mask is used to encode the notion of padding, in the usual raster-spatial data.

The transparency mask is a dual level image which can be superimposed with the picture described by the first IFD. The pixel value "1" means that the corresponding pixel in the main image is significant (it is part of the active area). Conversely, the pixel value "0" means that the corresponding pixel in the image have an unknown value (it is a padding pixel) and typically must be made transparent to the display.
A transparency mask contains no GeoTIFF tag. As part of this specification, it was decided to use a mask with the same resolution and size as the main image. The transparency mask is thus directly superimposed (pixel by pixel) in the master image.

Issue Links

is depended upon by

Bug - A problem which impairs or prevents the functions of the product. UDIG-1694 Can not display correctly some Geotiff

  • Major - Major loss of function.
  • Open - The issue is open and ready for the assignee to start work on it.

Activity

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Jody Garnett added a comment -
See UDIG-1694 for sample.zip containing the image in question; and a series of screen snaps.
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Jody Garnett added a comment - See UDIG-1694 for sample.zip containing the image in question; and a series of screen snaps.
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Even Rouault added a comment -
In my humble opinion, the transparency mask has not been generated correctly. I've extracted just the mask with the tiffcp utility from libtiff and it looks very strange and displayed it with OpenEV. It looks exactly like to geotiffZoom2.PNG from UDIG-1694. One can see some partial vertical lines made of "1" that are horizontally spaced by 8 pixels. The shape of the imagery is not recognizable either.
Show
Even Rouault added a comment - In my humble opinion, the transparency mask has not been generated correctly. I've extracted just the mask with the tiffcp utility from libtiff and it looks very strange and displayed it with OpenEV. It looks exactly like to geotiffZoom2.PNG from UDIG-1694 . One can see some partial vertical lines made of "1" that are horizontally spaced by 8 pixels. The shape of the imagery is not recognizable either.
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Daniele Romagnoli added a comment - - edited
I have attached a screenshot containing The Mask extracted from the sample.tif and loaded on QGis as well as on OpenEV
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Daniele Romagnoli added a comment - - edited I have attached a screenshot containing The Mask extracted from the sample.tif and loaded on QGis as well as on OpenEV
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Daniele Romagnoli added a comment -
I did the same thing of Even: I have extracted the mask from the sample.tif file through tiffcp.
Then, I have loaded the resulting mask tif on both QGis and OpenEV.
You can see the output on the attached Screenshot: http://jira.codehaus.org/secure/attachment/52011/extractedMaskOnViewers.png
As reported by Even, I think the mask has not been generated properly since the only thing you can see, it's something like several vertical lines. Maybe this is due to an improper operation performed by the software generating and storing the mask.

The user reporting the bug on UDIG-1694, states that GlobalMapper, QGis, and the Windows viewer properly opens the GeoTiff.
Maybe these tools are simply ignoring the Mask.


Show
Daniele Romagnoli added a comment - I did the same thing of Even: I have extracted the mask from the sample.tif file through tiffcp. Then, I have loaded the resulting mask tif on both QGis and OpenEV. You can see the output on the attached Screenshot: http://jira.codehaus.org/secure/attachment/52011/extractedMaskOnViewers.png As reported by Even, I think the mask has not been generated properly since the only thing you can see, it's something like several vertical lines. Maybe this is due to an improper operation performed by the software generating and storing the mask. The user reporting the bug on UDIG-1694 , states that GlobalMapper, QGis, and the Windows viewer properly opens the GeoTiff. Maybe these tools are simply ignoring the Mask.
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Daniele Romagnoli added a comment -
There are issues in the image, not in the plugin.
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Daniele Romagnoli added a comment - There are issues in the image, not in the plugin.
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Jody Garnett added a comment -
So can we have a switch to ignore the mask then? Or do you want me to just closed the linked uDig bug as won't fix.
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Jody Garnett added a comment - So can we have a switch to ignore the mask then? Or do you want me to just closed the linked uDig bug as won't fix.

People

  • Assignee:
    Daniele Romagnoli
    Reporter:
    Jody Garnett
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Dates

  • Created:
    Updated:
    Resolved: