Tagged Questions

1
vote
0answers
110 views

Handling “bad layers” in QGIS version 1.9

I'm having a problem every time I try and open any project in qgis 1.9. It will load part of a few layers and then a yellow bar comes up across the top of the map area that says "Handle Bad layers: 23 ...
3
votes
2answers
107 views

What Is The Ideal Workflow To Map (British) Postcode Territories

I'm looking for the best workflow for mapping postcodes and calculated territories, but being relatively new to mapping I'm struggling on a few details and also the best practices for displaying these ...
0
votes
1answer
78 views

How can i select many rows from a table?

I want to create an action that select many rows from PostGIS table to show many lines in QGIS. How can i select many rows from table with python to add these rows in a layer? Thank you
1
vote
1answer
75 views

How can I change SQL query through a layer of an action (python)?

I have three layers from three diferent database tables. When I click in other layer I want to change (with an action) the query of that three layers. How can I do that? Thank you
0
votes
1answer
72 views

In QGIS can I show just the lines in a Postgis query? How can I do that?

I have three tables in Postgresql, each table with one layer of lines. I want to show the path of an initial line to another final. Is it possible executing a SQL query? Thanks My three tables are ...
1
vote
1answer
61 views

Join attributes by date in Qgis

I learned (thanks!) to use the join feature built into the layer properties, but in my case it doesn't work because data do not match perfectly. Infact shape refers to geotagged photos, csv is a log ...
1
vote
0answers
65 views

How can I move two layers at once in QGIS?

I'm trying to move two digitized layers, one containing points, the other polygons to a different location at the same time. QGIS doens't seem to allow this. Even if I select both layers and features ...
0
votes
1answer
74 views

How do I style lines to show gradient colors for two attributes?

I have a layer with the city streets. I have a database with traffic values, including traffic going into the city and traffic going out from the city. I need to show the street links with different ...
0
votes
1answer
78 views

Split Map using Python in Qgis

I have a map, in which each region is defined as an attribute of the map (I can select each region from the attribute table). I am trying to create new layers each one containing only 1 region using ...
2
votes
1answer
139 views

How to realign (PostGIS) layers in QGIS?

I'm trying to realign layers in QGIS. As you can see here, the "background" light-blue layer is not aligned with the top layers. I'm working with pgAdmin III and importing PostGIS Layers in QGIS. My ...
4
votes
1answer
161 views

Extracting donut holes as separate layer in QGIS

Does anyone know how I can extract the holes in a polygon layer as a separate layer in Quantum GIS? An example could be a country with a number of lakes cut out of the polygon - I need the lakes. I ...
0
votes
0answers
65 views

How to apply an existing symbol in pyQGIS?

I'd like to change the layer rendering style from python code. Basically I want to do the same operations I can do from QGis by: Right-click on a layer Select Properties Select one of the displayed ...
2
votes
1answer
147 views

What is the easiest way to let a user upload overlayers to openlayers (Geoserver/Mapserver)?

I need to let a user upload vector layers he created with QGIS or MapInfo professional to my website (using OpenLayers as client and either Geoserver or Mapserver as WMS). What will be the easiest ...
5
votes
1answer
337 views

Sort layers in QGIS table of contents?

When I load a bunch of layers into QGIS from PostGIS, they seem to load in reverse alphabetical order. Is there any tools or plugins that allow you to quickly sort the QGIS TOC in a different order? ...
5
votes
1answer
104 views

How to convert PostGis Table (Grid data) to Continuous field using Qgis?

I'd like to transform my Gridded Layer (generated form a PostGIS table of points) to a continuous and colored layer. How could I do this with Qgis or any other program? Many thanks and best regards, ...
2
votes
1answer
177 views

QGIS identify features button issue

Is there anyway to get the Identify Features button in QGIS to automatically select a layer and provide the information without having to highlight it first in the layers TOC? MapInfo and ArcGIS ...
6
votes
4answers
1k views

How to georeference a vector layer with control points?

I have a non-georeferenced vector layer that I need to be georeferenced. With raster layers the task is easy and straightforward, but I have no idea what should I do with my vector layer. I have a few ...
3
votes
3answers
183 views

Why does the layer list context menu not open anymore?

I cannot access layers properties (i.e. change color, filter by query, anything). The mouse right click doesn't do anything. Is there a way restoring qgis to default? Ubuntu 12.04, QGIS 1.8
2
votes
0answers
370 views

legend groups and layer position/order qgis 1.8

I'm tring to programmatically create layer sequence also using groups. Simple python code: layer = QgsVectorLayer("004cp000.shp", "004cp000", "ogr") QgsMapLayerRegistry.instance().addMapLayer(layer) ...
1
vote
2answers
95 views

Fetching field values from uncommitted features on Qgis

I'm trying to fetch a feature's field value on Qgis, I use QgsFeature.attributeMap().value(cont int & key).toDouble() This works fine for committed features but it always returns " 0 " if the ...
2
votes
5answers
1k views

vector layer co-ordinate extraction QGIS

I add my own road vector data on top of Google map using open layers plugin with QGIS. The vector layer is generated using PostgreSQL DB. Is there any way to extract co-ordinates of a road segment ? ...
4
votes
2answers
356 views

How to copy a group of layers between QGIS projects?

In ArcGIS I am used to being able to have a couple of MXD documents open and copy-paste groups of layers from one MXD's table of contents to another. This can save a LOT of time ensuring consistent ...
4
votes
1answer
341 views

Can QGIS preserve layers?

I saw this posted about a year ago (Can QGIS preserve layers when exporting to PDF?) but figured it was worth asking again -- is this possible? My usual workflow with ArcGIS is to export to AI then ...
7
votes
2answers
912 views

How can I iterate over map layers in QGIS python

I'm having trouble figuring out how to iterate over map layers. I can access the currently highlighted layer in the table of contents via iface.activeLayer() but I want my code to operate on all ...
2
votes
2answers
1k views

Creating new layer from selection in Quantum-GIS

I have been using ArcMap for the last three years. But I am now considering switching to Quantum-GIS. Is it possible to create layers from selection in Q-GIS? I am using QGIS 1.7.4-Wroclaw. I will ...
3
votes
1answer
367 views

Can I change properties of several layers simultaneously?

I'm working on bulk data. I have a few hundred GeoTIFF images imported into a QGIS project, and I'd like to modify their layer properties - things like the no-data-value, transparency of certain pixel ...
2
votes
1answer
79 views

Keeping a vector layer always on top

I want to know how to keep a layer always on top of other layers! After adding a vector layer ( QgisInterface->addVectorLayer ), I want that layer to always be displayed on top of layers added later. ...
0
votes
1answer
254 views

Tiff raster display with polygon layer

Does any body have an idea about why *.tiff images are not displayed when added as raster layer to QGIS after adding a vector layer which has a polygon geometry? SOLVED !! In fact the tiff is ...