Feature request #14835

Virtual Raster Load Min Max Values

Added by Lene Fischer over 3 years ago. Updated over 2 years ago.

Status:Open
Priority:Normal
Assignee:-
Category:Rasters
Pull Request or Patch supplied:No Resolution:
Easy fix?:No Copied to github as #:22789

Description

New description:
#14835-8

Old description:
Hi
While creating a virtual raster the result viewed in the layer panel and in the map only shows values for the first rasterfile.
The solution is to enter the Properties>Style and to load min/max values.
If you want to change from singleband gray to singleband Pseudocolor the values are back to the first file again.
Regards Lene Fischer

raster.png (45.3 KB) Giovanni Manghi, 2016-05-23 01:01 AM


Related issues

Related to QGIS Application - Bug report #14853: Histogram min/max values markers and graph are always the... Closed 2016-05-22

History

#1 Updated by Lene Fischer about 3 years ago

When opening a singe file - the min/max is not loaded correct.
Link to data http://ku-gis.dk/blog/wp-content/uploads/2016/05/dtm_1km_6183_693.zip

#2 Updated by Giovanni Manghi about 3 years ago

  • Status changed from Open to Feedback

Lene Fischer wrote:

When opening a singe file - the min/max is not loaded correct.
Link to data http://ku-gis.dk/blog/wp-content/uploads/2016/05/dtm_1km_6183_693.zip

confirmed (but the description/title is about VRT files, so this may need a separate ticket, agree?).

[email protected]:~/Desktop/dtm_1km_6183_693 > gdalinfo -mm dtm_1km_6183_693.tif
Driver: GTiff/GeoTIFF
Files: dtm_1km_6183_693.tif
Size is 2500, 2500
Coordinate System is:
PROJCS["ETRS89 / UTM zone 32N",
    GEOGCS["ETRS89",
        DATUM["European_Terrestrial_Reference_System_1989",
            SPHEROID["GRS 1980",6378137,298.2572221010002,
                AUTHORITY["EPSG","7019"]],
            TOWGS84[0,0,0,0,0,0,0],
            AUTHORITY["EPSG","6258"]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433],
        AUTHORITY["EPSG","4258"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",0],
    PARAMETER["central_meridian",9],
    PARAMETER["scale_factor",0.9996],
    PARAMETER["false_easting",500000],
    PARAMETER["false_northing",0],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    AUTHORITY["EPSG","25832"]]
Origin = (693000.000000000000000,6184000.000000000000000)
Pixel Size = (0.400000000000000,-0.400000000000000)
Metadata:
  AREA_OR_POINT=Area
Image Structure Metadata:
  COMPRESSION=DEFLATE
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (  693000.000, 6184000.000) ( 12d 4'34.68"E, 55d45'47.20"N)
Lower Left  (  693000.000, 6183000.000) ( 12d 4'32.13"E, 55d45'14.90"N)
Upper Right (  694000.000, 6184000.000) ( 12d 5'31.97"E, 55d45'45.76"N)
Lower Right (  694000.000, 6183000.000) ( 12d 5'29.41"E, 55d45'13.46"N)
Center      (  693500.000, 6183500.000) ( 12d 5' 2.05"E, 55d45'30.33"N)
Band 1 Block=256x256 Type=Float32, ColorInterp=Gray
    *Computed Min/Max=-0.238,5.437*
  NoData Value=-9999

#3 Updated by Giovanni Manghi about 3 years ago

#4 Updated by Paolo Cavallini about 3 years ago

  • Subject changed from Virtuel Raster Load Min Max Values to Virtual Raster Load Min Max Values

#5 Updated by Lene Fischer about 3 years ago

Yes agree, but I can´t change the title :-)
Until this morning I thought it was related to VRT...

#6 Updated by Giovanni Manghi about 3 years ago

Lene Fischer wrote:

Yes agree, but I can´t change the title :-)
Until this morning I thought it was related to VRT...

I can change it.

Do you agree also to merge together with #14853 ? seems are two aspectes of the same issue.

#7 Updated by Lene Fischer about 3 years ago

Yes

#8 Updated by Giovanni Manghi about 3 years ago

  • Operating System deleted (Windows 64 bit)
  • Affected QGIS version changed from 2.14.2 to master
  • OS version deleted (2.14.2)
  • Target version deleted (Version 2.14)

Lene Fischer wrote:

Yes

Hi Lene,
it seems there is "no issue" after all.

QGIS by default computes min/max using by default an accuracy that is set to "estimated (faster)" and this gives "wrong" results, but if you switch to "Actual (slower)" then the values are the same as gdalinfo (both for single files or vrt rasters).

I think that we can argue why using "estimated" by default and why this give min/max values that are so different (at least in cases as your dataset) from real values. I guess we have to choose another title/description for this ticket if decide that this is indeed worth to be left open.

Note:
at this point #14853 is another issue: in the histogram graph min/max markers/graph are always set to the values computed as "estimated" even if the numeric values are the ones computed as "actual".

#9 Updated by Giovanni Manghi about 3 years ago

  • Tracker changed from Bug report to Feature request
  • Status changed from Feedback to Open

#10 Updated by Giovanni Manghi over 2 years ago

  • Easy fix? set to No

#11 Updated by Jürgen Fischer over 2 years ago

  • Related to Bug report #14853: Histogram min/max values markers and graph are always the ones for values computed as "estimated" added

#12 Updated by Jürgen Fischer over 2 years ago

  • Description updated (diff)

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