Bug report #1380
No Data values are counted as values in the histogram
Status: | Closed | ||
---|---|---|---|
Priority: | High | ||
Assignee: | - | ||
Category: | Rasters | ||
Affected QGIS version: | master | Regression?: | No |
Operating System: | Easy fix?: | No | |
Pull Request or Patch supplied: | No | Resolution: | duplicate |
Crashes QGIS or corrupts data: | No | Copied to github as #: | 11440 |
Description
After setting a given value as No Data for a raster, the histogram
and min-max statistics are not updated.
Y axis in the histogram is often too high
History
#1 Updated by Giovanni Manghi over 15 years ago
Seems to me still true on qgis 1.2 from trunk under Ubuntu 9.04
#2 Updated by ersts - over 15 years ago
- Status changed from Open to Closed
- Resolution set to fixed
fixed in 1c3390e1 (SVN r11190)
#3 Updated by ersts - about 15 years ago
- Status changed from Closed to Feedback
- Resolution deleted (
fixed)
I have to reopen this. The nodata values were removed from the raster band stats, but they are still showing up in the histogram. It is either something to do with the GDALGetRasterHistogram() or the logic behind which bins to display in QgsRasterLayerProperties::on_pbnHistRefresh_clicked() or a combination of both
#4 Updated by Paolo Cavallini about 15 years ago
Perhaps related to that: if you build pyramids, the histogram will count all the cells from all levels of pyramids as valid values, thus giving inflated and incorrect results
#5 Updated by Paolo Cavallini about 15 years ago
Confirmed this in Windows XP, not in a fresh Debian box
#6 Updated by alobo - about 14 years ago
- Status changed from Feedback to Open
Hi Agus,
As far as I know this is so because your raster does not define a null
value in the GDAL sense (use GDAL tools to set a null value for that
raster, NOT the QGIS raster properties)
Yes (as extremely delayed feedback to Benoit too) I plan to rewrite
the raster histogramming at some point to not use gdal so that we can
take into account user defined transparency settings etc. I will do
this when I get a few hours to spare!
Regards
Tim
Hope this helps,
BenoitOn 01/12/2010 17:14, Agustin Lobo wrote:
Raster histograms include null values, which in many cases severely distorts the
histograms (i.e., images in which a large part of ocean is present or
just images
in which the scene is not a rectangle)
Also, the ability to customize the axes (in particular the x axis) is
very important
#7 Updated by Alister Hood about 13 years ago
- Pull Request or Patch supplied set to No
Nodata values are also counted when using the "load min/max values from band" feature on the "Style" tab.
This was supposed to be fixed a long time ago: #857-2
I guess I should probably reopen that bug, or file a new one... but it might be the same issue as this with the histogram.
Should this really be "low" priority?
#8 Updated by alobo - about 13 years ago
- Priority changed from Low to High
#9 Updated by Giovanni Manghi about 13 years ago
- Target version changed from Version 1.7.0 to Version 1.7.4
#10 Updated by Giovanni Manghi about 13 years ago
- OS version deleted (
ubuntu 8.04, ubuntu 9.04) - Crashes QGIS or corrupts data set to No
- Assignee deleted (
Tim Sutton) - Operating System deleted (
Linux) - Affected QGIS version set to master
Probably this is related/duplicate/consequence of #3840
Actually the "no data value" does not make anything NULL, it just turn the pixels transparent, but they retain they original value.
#11 Updated by Paolo Cavallini almost 13 years ago
- Priority changed from High to Normal
#12 Updated by alobo - over 12 years ago
- Priority changed from Normal to 6
#13 Updated by Giovanni Manghi over 12 years ago
- Priority changed from 6 to High
#14 Updated by Paolo Cavallini over 12 years ago
- Target version changed from Version 1.7.4 to Version 1.8.0
#15 Updated by Paolo Cavallini over 12 years ago
- Target version changed from Version 1.8.0 to Version 2.0.0
#16 Updated by Giovanni Manghi about 12 years ago
- Status changed from Open to Closed
- Status info deleted (
0) - Resolution set to duplicate
Duplicate of #3840