"Clip raster by mask layer" produces different results than "Clipper" from Raster Menu

[qgib]

Author Name: Filipe Dias (@fsdias)
Original Redmine Issue: 9400
Affected QGIS version: 2.4.0
Redmine category:processing/gdal
Assignee: Alexander Bruy

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I tried clipping a raster with "Clipper" from the Raster Menu and "Clip with mask layer" from the Processing Toolbox and obtained different results

The outputs of both functions had:

• different raster statistics (Layer properties ->Metadata->Band 1)

• handled no "NoDataValues" differently. While Clipper kept "NoDataValue" undefined, Clip with mask layer assigned "0" as NoDataValue, even though I set "none" in Nodata value

Am I missing something? I attached test data to reproduce the issue

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• clip.zip (Filipe Dias)

[qgib]

Author Name: Filipe Dias (@fsdias)

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SAGA 2.10/"Clip grid with polygon" produced a raster with the same statistics as the output from "clip raster with mask layer" and assigned -32767 as NoDataValue

[qgib]

Author Name: Giovanni Manghi (@gioman)

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The different stats are explained because all the pixels that have 0 value are evidently counted in the stats (that does not happens for NO DATA).

If you need to have NO DATA in the output from the tool in the raster menu then you must check the "no data value" option (and set it to 0).

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• status_id was changed from Open to Closed

[qgib]

Author Name: Filipe Dias (@fsdias)

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Giovanni Manghi wrote:

The different stats are explained because all the pixels that have 0 value are evidently counted in the stats (that does not happens for NO DATA).

You're right

But one issue remains: if the original raster doesn't have a NoDataValue, then the tool in the processing toolbox automatically assigns it to 0. The function "clipper" does not do this.

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• status_id was changed from Closed to Reopened

[qgib]

Author Name: Giovanni Manghi (@gioman)

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Filipe Dias wrote:

Giovanni Manghi wrote:

The different stats are explained because all the pixels that have 0 value are evidently counted in the stats (that does not happens for NO DATA).

You're right

But one issue remains: if the original raster doesn't have a NoDataValue, then the tool in the processing toolbox automatically assigns it to 0. The function "clipper" does not do this.

to me makes much more sense that the areas outside the clipped area are NO DATA rather than 0. So in this sense the processing tool acts better by default than the tool in th vector menu, that has the option unchecked.

[qgib]

Author Name: Filipe Dias (@fsdias)

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There is that. But maybe the tool in the Raster Menu was designed that way because of some use case?

Anyway, it's important that both tools behave the same way.

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• project_id was changed from 78 to 17
• crashes_corrupts_data was configured as 0
• version was configured as 2.4.0
• category_id removed 58

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• category_id was configured as Processing/GDAL

[qgib]

Author Name: Alexander Bruy (@alexbruy)

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Works fine in master. There is a minor difference in statistics cause by the fact that Processing tool aligns the coordinates of the extent of the output file to the values of the resolution ("-tap" option).

Please reopen if necessary.

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• status_id was changed from Reopened to Closed