Opened 15 years ago

Closed 15 years ago

Last modified 14 years ago

#778 closed bug (fixed)

Displaying raster images extremely slow

Reported by: cdavila Owned by: homann
Priority: critical: causes crash or data corruption Milestone:
Component: Rasters Version: Trunk
Keywords: Cc: cdavilam@…, msieczka, warmerdam
Must Fix for Release: Yes Platform: Debian
Platform Version: testing Awaiting user input: yes


After updating from 0.8.1 to 0.9 ecw rester images that before were displayed at once now take very long time: 4 images of 9 MB each one take about 8 minutes and images of about 700 MB don't display after one hour. More information can be found here: Reproduced in two machines with debian-testing and reported by other user in windows XP

Attachments (1)

diff_7951_vs_7952 (2.5 KB ) - added by cdavilam 15 years ago.
Diff between revisions 7951 and 7952

Download all attachments as: .zip

Change History (13)

comment:1 by cdavila, 15 years ago

Cc: cdavilam@… added
Platform Version: testtingtesting

I have just replace 0.9.0 package with 0.9~svn20071023-1 from and the problem has disappeared.

comment:2 by homann, 15 years ago

Awaiting user input: set
Owner: changed from nobody to homann
Status: newassigned

Let's check with 0.9.1 when it is released.

comment:3 by homann, 15 years ago

0.9.1 is now released. I believe this error has disappeared. Can you check?

comment:4 by cdavila, 15 years ago

I'm still not using definitive 0.9.1, but 0.9.1~pre20071219 from, but problem has certainly disappeared, so I think bug can be closed if no one has same problem.

comment:5 by homann, 15 years ago

Resolution: fixed
Status: assignedclosed

I also noted slow performance on 0.9.0, but not anymore.

comment:6 by cdavila, 15 years ago

Resolution: fixed
Status: closedreopened

I'm having the same problem again. Tested with versions r7994, r8009 and r8022 and in two different machines. Not with 0.9.1 packages.

comment:7 by cdavilam, 15 years ago

The problem persists in r8223. Now a bug squashing is being planned, I would really appreciate if this bug is resolved, as I need to use ecw rasters in my daily work and it's really annoying to wait so much time each time I move map canvas, having to use other programs too often.

comment:8 by msieczka, 15 years ago

Cc: msieczka added

I'm not sure if this is relevant, but in general QGIS is very slow displaying tiled GeoTIFFs. Stripped GeoTIFFs display about 10 (ten) times faster.

Stripped GeoTIFF can be created with:

gdal_translate -co "TILED=NO"

and a tiled one with:

gdal_translate -co "TILED=YES"

by cdavilam, 15 years ago

Attachment: diff_7951_vs_7952 added

Diff between revisions 7951 and 7952

comment:9 by cdavilam, 15 years ago

After some investigation compiling various revisions, I have found this bug was introduced in r7952. I have attached diff between revisions 7951 and 7952. Log for r7952 is:

r7952 | ersts | 2008-01-14 04:48:11 +0100 (lun, 14 ene 2008) | 1 line

-Set default contrast enhancement to STRETCH_TO_MIN_MAX

comment:10 by warmerdam, 15 years ago

Cc: warmerdam added

comment:11 by ersts, 15 years ago

Resolution: fixed
Status: reopenedclosed

There is now an ability to set the default contrast enhancement that will remain persistent between sessions, which resolves this problem to some extent. If stretching is too slow and not needed, the user can elect not to stretch on initial load.

I think this closes this ticket for QGIS, if there are any upstream issues with GDAL that are also fixed in the future, all the more better.

If this is still not a satisfactory solution, feel free to reopen.

comment:12 by (none), 14 years ago

Milestone: Version 0.9.2

Milestone Version 0.9.2 deleted

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