Misalignment of an imported .asc raster

[pcav]

• import (-o) the .asc file from ​https://www.dropbox.com/s/w60ywwddl3aj03h/cavallini.zip
• r.to.vect

(you can see the results of these operations in the location, in the zip above)

Display raster and vector, either in GRASS or in QGIS (in this second you can also load the original raster).

Results: the original raster and the derived vector align perfectly, the imported raster shows shifts while zooming in and out. See attached screenshots as an example.

Additionally, in qgis-dev I get errors querying the raster: 168 bytes expected but 3200000 byte were read from qgis.d.rast

Tested on 3 different machines (Debian Unstable, Ubuntu, Windows).

[mmetz]

Replying to pcav:

• import (-o) the .asc file from ​https://www.dropbox.com/s/w60ywwddl3aj03h/cavallini.zip
• r.to.vect

(you can see the results of these operations in the location, in the zip above)

Display raster and vector, either in GRASS or in QGIS (in this second you can also load the original raster).

In the first (GRASS), you can also load the original raster via r.external.

Results: the original raster and the derived vector align perfectly, the imported raster shows shifts while zooming in and out. See attached screenshots as an example.

Looking at the metadata:

> g.region -g zoom=GR23B07 rast=GR23B07
n=4895155
s=4894780
w=1568780
e=1569043
nsres=1
ewres=1

> v.info -g map=G23B07vectV
north=4895155
south=4894780
east=1569043
west=1568780

The raster and the vector are exactly aligned, also when displayed with GRASS wxGUI at different zoom levels, both with GRASS 6.4 and GRASS 7.

The attached screenshots 33.png and shot2.png are not made from GRASS display with the location in cavallini.zip. Please try to display the imported raster map and the derived vector map in the GRASS location in cavallini.zip using GRASS.

Additionally, in qgis-dev I get errors querying the raster: 168 bytes expected but 3200000 byte were read from qgis.d.rast

File a bug for qgis?

Tested on 3 different machines (Debian Unstable, Ubuntu, Windows).

Unfortunately, the misalignment is not reproducible by others (at least 3 different people with different OS's and different GRASS versions).

Markus M

[pcav]

OK, let's see if it's a pure qgis problem then.