4,247 reputation
11224
bio website whatutmzoneamiin.blogspot.com
location Ontario, Canada
age 33
visits member for 4 years
seen 12 hours ago

Open source GIS user & advocate.


Sep
25
comment QGIS, drawing entity with a magnetized knot
I'm guessing you may mean 'snapping'? If so, check the Snapping Options in QGIS, or do a search using that as a keyword.
Sep
18
comment Unknown red rectangle appears in map window
Glad to hear it Silvia. If this answered your question, please mark my answer as the accepted answer.
Sep
16
comment Unknown red rectangle appears in map window
QGIS editing doesn't have the concept of a 'region' and thus would have no reason to have an extent rectangle shown. As per my answer, the rectangle is the Grass region being shown.
Sep
5
comment Wrong $area from field calculator (QGIS)
Is it possible you have multipolygons, and the $area is returning the total area of all constituent pieces?
Jul
25
comment Extract one GPS fix per day from data?
In this case, however, it would not, especially given the colon at the end of the 12--even December would not match that pattern. Obviously it's a very data-specific answer, and your answer would work for other data.
Jul
23
comment Displaying large number of polygons on web map?
If you are open to different platforms, you may want to take a look at GIS Cloud. Their HTML5 Canvas implementation is able to handle huge datasets: directionsmag.com/articles/…
Jun
25
comment How to create atlas along line/route in QGIS
Are you sure you have "Controlled by Atlas" enabled under the map frame "Item Properties", with a "Margin Around Feature" set (to say 10%)? You should have a page centered on each feature, with the appropriate margin. If you're only getting a small segment (smaller than your 'split' length?) then you've got something set wrong.
Jun
25
comment Qgis making a backgound map for topolines on Garmin
It creates a raster map in .kmz format.
Jun
25
comment How to create atlas along line/route in QGIS
Adam; the Atlas by default will rotate to follow each segment of the "Coverage Layer" -- is it not doing so?
Jun
24
comment How to create atlas along line/route in QGIS
What I would do is "split" your linear layer into a second layer (for using in your atlas only) using v.split.length under Processing (it's a GRASS tool.) Set this as your "Coverage Layer," make it invisible so it doesn't show up on the map, and you're all set. The Atlas pages will then follow the line, rotate appropriately, and overlap based on the 'buffer' you set, which should meet all of your criteria.
Jun
13
comment Split Lines at Intersection of Other Lines
This is bizarre. I just tried the exact same syntax with a single subset (one road, one contour) and it worked exactly as expected. When I run it on the larger database, it doesn't work!
Jun
13
comment Split Lines at Intersection of Other Lines
After viewing the results, it in fact does not appear to work. It simply output my original roads. What am I doing wrong here? SELECT ST_AsText(ST_Split(r.geom, c.geom)) as geom FROM roads r, contour c
Jun
13
comment Split Lines at Intersection of Other Lines
After some more work, I was able to import the data using the DB Manager Plugin, and checked off "Create Single Part Geometries instead of multi-part" and it seems to work!
Jun
13
comment Split Lines at Intersection of Other Lines
Thanks! I am not familiar enough with Python to try your first solution just yet. The OpenJump solution somewhat works, but leaves all of the data in one layer, with no attributes present to separate them back out into the original layers. Any thoughts on how to do this?
Jun
13
comment Split Lines at Intersection of Other Lines
Thanks! I was able to mess around with this a bit, and found it didn't quite work. I had the error "Splitting a Line by a MultiLineString is unsupported." After some further research, it seems that ST_LineMerge may solve the problem, so I tried: 'SELECT ST_Split(r.geometry, c.geometry) FROM (SELECT ST_LineMerge(geom) from contour AS linemergec) c, (SELECT ST_LineMerge(geom) from roads AS linemerger) r' - but now I'm getting the error: "cannot cast type record to topogeometry ^ DETAIL: Cannot cast type geometry to integer in column 1"
Jun
13
comment Is it possible to create Rule-Based Styling with $geometry intersecting a second layer?
Thanks underdark; at least I wasn't missing something! I figured perhaps it was not possible.
Jun
6
comment Is it possible to create Rule-Based Styling with $geometry intersecting a second layer?
The second layer is a polygon shapefile that has been added to the QGIS project.
May
29
comment Split Lines at Intersection of Other Lines
gene; as per my above comment, the Union in OpenJump is not working as expected (in fact it is doing nothing.) I also noticed that there are multiple Union commands (which is bizarre). Can you walk me through that step? How is Tools>Analysis>Union/Dissolve/Merge command different than Tools>Geometry Functions>Union (Function)? Neither of these seem to make sense based on any "Union" command I have used in other software.
May
28
comment Split Lines at Intersection of Other Lines
gene; can you walk me through this? I can't actually seem to perform a Union of the two line layers in OpenJump either--it just does nothing, presumably because it is also expecting a polygon layer as one of the inputs.
May
27
comment Split Lines at Intersection of Other Lines
Care to expand on that with a possible solution?