QGIS » QGIS Application

File is too big to be attached (3 MB) so I put it on http://kosatka.fns.uniba.sk/~1balazovic/qgis/layer.tar.gz

Works for me with qgis 3a8b8164 (SVN r2579), gdal version 1.2.6. It does however take about 30 seconds to display the map. This is probably due in part to the large size of each separate geometry. The .shp file is 7.8MB, but there are just 36 polygons in it. Can you confirm that the layer eventually loads if you wait long enough?

Version of Qgis : Qgis-user] QGIS 0.8.0 Preview Release 1 source downloaded and compiled this morning.

The layer d09_pente_vecteur_class.shp (see http://dedibox.acacs.org/pentes/ ) can be opened, but it takes 11 minuts on my machine:

cat /prop/cpuinfo

processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 9
model name : Intel(R) Pentium(R) M processor 1500MHz
stepping : 5
cpu MHz : 1499.879
cache size : 1024 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr mce cx8 sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 tm pbe est tm2
bogomips : 3001.08

Then the zoom in is fast, but the zoom out to full extent take about 10 minuts.

This layer is opened in 11 seconds on qgis 0.7.4 and 9 seconds on Arcexplorer 4 Java Edition.

Do you have anti-aliasing turned on in qgis? Could you try loading your layer with and without anti-aliasing to see if there is a large time difference?

The files are a bit big for me to download over my dialup modem, so if you could also run 'ogrinfo -a d09_pente_vecteur_class.shp' and let us know how many features are in the file that would be useful too.

-anti-aliasing turned of in qgis= 11 minuts to download d09_pente_vecteur_class.shp

-anti-aliasing turned on in qgis= 3 minuts 30 seconds to download d09_pente_vecteur_class.shp, but a zoom in is 12 minuts !

-extract of the command: ogrinfo -a d09_pente_vecteur_class.shp

Beginning and end of the output.(The full output is at http://dedibox.acacs.org/pentes/ogrinfo_a_d09.zip )

INFO: Open of @/home/bernard/MNT_classes/d09_pente_vecteur_class.shp'
using driver @ESRI Shapefile' successful.

Layer name: d09_pente_vecteur_class
Geometry: Polygon
Feature Count: 141953
Extent: (476460.000000, 1729980.000000) - (586800.000000, 1813140.000000)
Layer SRS WKT:
(unknown)
cat: Real (11.0)
value: Real (11.0)
label: String (80.0)
OGRFeature(d09_pente_vecteur_class):0
cat (Real) = 2
value (Real) = 3
label (String) = de 5 à 10
POLYGON ((476550 1813140,476640 1813140,476640 1813050,476550 1813050,476550 1813140))

OGRFeature(d09_pente_vecteur_class):1
cat (Real) = 3
value (Real) = 4
label (String) = de 10 à 15
POLYGON ((476640 1813140,476730 1813140,476730 1813050,476910 1813050,476910 1813140,477180 1813140,477180 1813050,477090 1813050,477000 1813050,477000 1812960,477090 1812960,477090 1812870,477000 1812870,477000 1812780,476910 1812780,476910 1812870,476730 1812870,476730 1812960,476640 1812960,476640 1813050,476640 1813140))

OGRFeature(d09_pente_vecteur_class):2
cat (Real) = 4
value (Real) = 5
label (String) = de 15 à 20
POLYGON ((476730 1813140,476910 1813140,476910 1813050,476730 1813050,476730 1813140))

OGRFeature(d09_pente_vecteur_class):3
cat (Real) = 5
value (Real) = 3
label (String) = de 5 à 10
POLYGON ((477180 1813140,477360 1813140,477360 1813050,477270 1813050,477180 1813050,477180 1813140))
......
......
OGRFeature(d09_pente_vecteur_class):141949
cat (Real) = 141193
value (Real) = 5
label (String) = de 15 à 20
POLYGON ((583380 1729980,583380 1730070,583470 1730070,583470 1729980,583380 1729980))

OGRFeature(d09_pente_vecteur_class):141950
cat (Real) = 141195
value (Real) = 4
label (String) = de 10 à 15
POLYGON ((584550 1729980,584550 1730070,584640 1730070,584640 1729980,584550 1729980))

OGRFeature(d09_pente_vecteur_class):141951
cat (Real) = 141196
value (Real) = 3
label (String) = de 5 à 10
POLYGON ((586260 1729980,586260 1730070,586350 1730070,586350 1729980,586260 1729980))

OGRFeature(d09_pente_vecteur_class):141952
cat (Real) = 160000
value (Real) = 0
label (String) = a la main
POLYGON ((512523.781980661384296 1735157.792264741146937,512523.782013707736041 1735157.792264741146937,512523.782002692285459 1735157.792215171502903,512523.781980661384296 1735157.792215171502903,512523.781980661384296 1735157.792215171502903,512523.781980661384296 1735157.792264741146937))

As a side note, its worth building a spatial index on your shapefiles - it should offer significant performance improvement for zoomed in redraws. It takes a couple of seconds only to redraw when zoomed in on my 1.5ghz pc with indexes built.

When trying the sample layer from lulaby I've found out that it's once again bug in Qt - this very long rendering time takes place when QImage is used for rendering, with QPixmap it's OK.

The question is how to fix this issue - use QPixmap by default and offer QImage rendering just as "unstable" option?

This bug is also in newly released Qt4.2 RC1, together with bad polygon filling. Might be interesting to try to create an example from this data for Trolls...

Tested again with Qt 4.2.1 with following results how long it has been rendering:

• antialiasing off, rendering to QImage: 40 seconds + bad polygon filling
• antialiasing on, rendering to QImage: 6 seconds
• antialiasing off, rendering to QPixmap: 4 seconds

Milestone Version 0.8 deleted