QGIS is a user-friendly, cross-platform GIS application licensed under the GNU General Public License.

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3
votes
3answers
634 views

Convert 800 .hdf4 files to Tiff using GRASS/QGIS/SAGA/GDAL/R

I've have MODIS ndvi data (MODIS_Grid_16 days NDVI) from the iberian peninsula, from February of 2000 to August of 2012 (really big data). How do I batch convert about 800 .hdf MODIS files to .tif ? ...
3
votes
1answer
616 views

QGIS 2.2 problem, loading layer into road graph

I have the road graph plugin installed, but when I try to configure it with the Settings dialogue, no layer names appear in the Layers field. I have tried various shapefiles, but the Settings dialogue ...
3
votes
1answer
242 views

Show alternating contour lines

Is it possible to show only every other counture line? And how do you do that? (Im new to QGIS Lisboa 1.8.0, but even newer to QGIS Dufour 2.0.1, but have used ArcGIS a bit a while ago, and also ...
3
votes
2answers
867 views

How to resize the map item in QGIS print composer without changing scale?

Is it possible to lock the scale in the QGIS 2.0.1 print composer? Every time I resize the map, the scale is adjusted. This makes trying out different map layouts really annoying.
3
votes
3answers
1k views

QGIS - Convert Vector points to GPS waypoints and route

I'm new here. I have a shape file with a series of points (around 300) using British National Grid. I need to put them on my Garmin Etrex 10 as waypoints. Can someone tell me how to convert this ...
3
votes
2answers
1k views

how to for loop a folder to batch clip rasters by polygon using python and QGIS

I am using python and QGIS 2.0. I am trying to clip rasters in a folder by one polygon feature. It's the first time for me using (let's say) "PyQGIS", I was used to arcpy before. Anyway, I don't get ...
3
votes
1answer
1k views

What expressions for QGIS field-calculator?

I do not understand what language I have to use in field-calculator and labels on QGIS: SQL or Python? And where I can find the possible script/expressions to use? in the image you can see the ...
3
votes
1answer
2k views

How to manually edit point coordinates in QGIS?

Is there a tool for shapefiles or a QGIS plugin available, which will enable me to edit the coords of a point manually ? ("tool" -f1 "Tsunami Gauge"-move x1.abcdef -to x2.ghijkl) I do have ...
3
votes
1answer
529 views

Watershed extraction using different DEM tiles

I would like to extract the watersheds for a particular area using QGIS. However, I only have Aster 30m DEMs to work with, each tile covering one degree square. The problem is that I need to use ...
3
votes
2answers
246 views

How to write an equivalent to MapBasic's CreateLine in pyQGIS?

I know this kind of question has been asked, in part, before - specifically: Seeing QGIS Python Commands and: How is object created as line using createline stored in .tab file? but this is a specific ...
3
votes
1answer
677 views

How to set up QGIS print composer options from the python console?

If I have a print composer called "ABC", I would like to "tell" its composer that I would like to update "Map 0" to simulate the "set to map canvas extent" button activation update certain text ...
3
votes
1answer
770 views

How to get the distances (shortest path) between all pairs of points in the river network?

I have 2 vector shapefiles (one line, one point), and I have tried at least 4 ways to try to get the distance matrix at one time (and most concern the directions of each river segment) quantum ...
3
votes
2answers
534 views

Creating seperate layers out of one big polygon shape by using attributes

I try to explain may problem. I have a big polygon shape (> 200 fields). I have the owners of these fields in a column. I need the seperated shapes for each owner. Is there a tool to do that? Is it ...
3
votes
5answers
2k views

Batch processing DEM rasters in QGIS/GDAL

I am attempting to add relief shading to map using .asc raster files, following this tutorial. It works well, but I have only tried it on single tile of raster data which is 20x20km. I want to ...
3
votes
1answer
160 views

Button to add a new line in a non-spatial table without opening the table itself using QGIS?

While using QGIS and having loaded a non spatial table (from PostGIS), is it possible to add a new row to its table attributes without having to open the attribute table first as in here Is it ...
3
votes
1answer
297 views

How to create a line with start and end points which are in another layer in QGIS?

In my map, there are lots of points in layer A. I want to make a line layer B and I want to make start & end points of lines snapping to points in layer A manually. Can I use points of layer A as ...
3
votes
2answers
343 views

Looking for qml specification

Where I can find qml specification which is used for store symbology information in QGIS? Try to googe it - no result.
3
votes
1answer
2k views

What's the proper format for WKT linestrings when importing into QGIS?

I'm trying to run the following test CSV through the Delimited Text plugin as WKT data: oid,Line 1,LINESTRING((45.554194 -122.686101, 45.433001 -122.762632)) 2,LINESTRING((45.432505 -122.598327, ...
3
votes
2answers
289 views

Why can't I see all records in my personal GDB in QGIS?

I am running QGIS 1.8. I have a layer from an ESRI Personal GDB. There are 431 features in the layer. When you load the layer into QGIS, and look at the Metadata properties, it shows the number of ...
3
votes
1answer
480 views

QGIS Polygon layer table of adjacent polygons

In a polygon layer, how can I generate a table of adjacent polygons?
3
votes
2answers
2k views

How to perform volume calculation in QGIS

EDIT 07/12/12 Ok, meanwhile I came to another problem I want to discuss. I just tried around with the volume calculation with some layers and came to a point where I receive the following error. ...
3
votes
4answers
7k views

How can I import georeferenced photos (jpg, kml, kmz) using QGIS or ArcGIS for Desktop?

I've got several georeferenced digital photos as jpg, kml, and kmz. How can I import them into my GIS projects (QGIS or ArcGIS for Desktop) so I can open them as a popup?
3
votes
3answers
1k views

How to extract the US from a North America Shapefile?

I have a north america shapefile, downloaded from ftp://ftp.epa.gov/wed/ecoregions/cec_na/NA_CEC_Eco_Level2.zip How can I get a new shapefile from this showing only us? Is there a way doing this in ...
2
votes
1answer
68 views

Finding and using data on population density files

I'm attempting to replicate this map for the state of Nevada in QGIS: source: http://www.bostonfed.org/commdev/c&b/2014/spring/map-distance-to-closest-snap-outlet.htm (A SNAP outlet is just a ...
2
votes
1answer
104 views

QGIS crash when I try print geometry

I do (it works): from osgeo import ogr inputds = ogr.Open(r'c:\temp.shp') inputlyr = inputds.GetLayer() for i,feature in enumerate(inputlyr): print i, feature.GetGeometryRef() Output: 0 ...
2
votes
1answer
185 views

How to create a catchment from a point using a DTM raster in QGIS?

I need to find a better way to delineate a catchment from a given point on a watercourse using a DTM - currently I am either using FEH, or if the catchment is too small using contours to draw ...
2
votes
1answer
112 views

QGIS show gdal_polygonized file in EPSG:54004 instead of EPSG:3857

I am polygonizing a TIFF with the gdal_polygonize.py and the resulting Shape is shown in QGIS in the wrong projection - EPSG:54004 instead of EPSG:3857. I have a TIFF in EPSG:3857 and polygonize it ...
2
votes
2answers
164 views

Auto populate field as concatenation of other fields

I'm searching for a way to automatically combine several field values entered in the feature edit dialogue, resulting in a new column comprised of the former values. I have, say fields A, B and C ...
2
votes
1answer
145 views

How to exactly georeference in QGIS

When I georeference a raster image in QGIS, it's always a bit displaced as in the attached image (the cyan polygon is the template, the red border is the georeferenced image), although I try to set ...
2
votes
1answer
156 views

Route to cover entire network

I have a road network where I have to cover every road for visual inspection. I need to design a route map for this task. What tools are available to a QGIS user? How would you describe the workflow ...
2
votes
3answers
161 views

How to apply a specific Rendering to an Image and export to JPEG?

We have a specific process which generate an interpolated single band 32-bit Float Raster in Erdas Imagine (.IMG) format. This process generates an image every hour. We wish to apply a specific ...
2
votes
1answer
339 views

How to import a 3D DXF file into QGIS with z information as attribute value?

I have a dxf file of 3d contours. after import it does have only layer,x,y attribute and doesn't have Z attribute. how can I provide Z attribute to create a TIN file.
2
votes
1answer
165 views

QGIS 2.2 Raster Merge losing color data

I'm trying to merge a couple of GeoTiff maps using Raster > Miscellaneous > Merge but the merge is only coming out in grayscale. The geotifs are using palettes color. How do I get the merge to keep ...
2
votes
1answer
838 views

How to identify line intersection in QGIS when I have more than 2 lines?

I am trying to identify where overlaps exist between multiple shapefiles. I would use the intersect tool, but it only allows me to intersect two layers. I have over one hundred individual line ...
2
votes
2answers
765 views

Unable to load 'nviz' through GRASS

I am using QGIS 2.0.1-Dufouron on Windows 7. When I try to load nviz via GRASS, I get the message "Module nviz not found". Weirdly enough, I can load it via the toolbox and be able to 'run' it (it ...
2
votes
1answer
159 views

Why does writing large shapefiles crash QGIS?

I'm trying to write large shapefiles with QGIS 2.0 API, using Python, which crashes QGIS. The data is composed of simple two point lines and a data table of five columns. A thousand features or so ...
2
votes
0answers
146 views

Accessing existing instance of qgis from stand-alone python script

For my own data analysis pipeline, I am running a split screen setup with iPython notebooks on one side, generating variables from source data, pushing them to a csv file which qgis then reads/joins ...
2
votes
0answers
213 views

how to make decent sense from scattered river depth measurements

I sampled river depth at scattered positions and I want to be able to make a map and GIS layers out of it. My problems are: As the river meanders the interpolation I do in scientific packages i,e. ...
2
votes
3answers
222 views

Census.gov TIGER down, suggestions?

Census.gov is down for now. I have a friend who is a teaching a GIS class in the San Francisco bay area and only has so many datasets downloaded for specific projects. Does anyone have a large copy ...
2
votes
1answer
2k views

interpolation methods in qgis

I have a points layer and I want to create an interpolation grid with QGIS 2.0. If I use Raster -> Analysis -> Interpolation the extent of the output raster is good (rectangular shape) but it ...
2
votes
3answers
1k views

Add points for every 100 m at polyline (QGIS/Mapinfo)

I have a polyline and want to set points for every 100 m. And if possible, with unique values for each point, 100, 200, 300 etc. Can it be done? The QGIS-plugin, Sextante algoritmes "v.to points" ...
2
votes
2answers
3k views

Exporting shapefile to PostGIS database in QGIS

How do I export a vector shapefile to PostGIS database? I am asking what format I have to export it.
2
votes
2answers
332 views

Vehicle tracking by QGIS

I need to do routing for a vehicle. A map with detailed turn-by-turn driving directions should be generated. For example, it should be like car race game in which the map with vehicle tracking is ...
2
votes
2answers
1k views

Local Tile Cache in QGIS

I was wondering if there is a way to load a local tile cache (ie: MB Tiles etc.) of imagery that is sitting locally into QGIS? I am hoping to use some tablets for field verification and would like to ...
2
votes
1answer
442 views

How to keep the same style of a OSM map converted to SHP file

I saved a OSM file as a Shapefile, this is fixing my previous question how to handle bad layers. My question is how to retain the original style from OSM plugin to SHP files, when I copy the style ...
2
votes
1answer
2k views

How to find the watershed area for each point in the river network using DEM?

Update#1: Thanks, Micha, I have followed your instruction and successfully use the modules in GRASS. I use r.watershed to get the basin raster and the drainage line: and I use r.water.outlet to get ...
2
votes
0answers
108 views

Raster area (QGIS) problem explained

I would like to know the area that each value in a raster has... The raster I have has values from 2-15 and I would like to know the area that each value is occupaying within my polygon... Thanks! I ...
2
votes
3answers
316 views

How to route railcars along railroads?

I'm very new to the world of GIS, but I'm learning a great deal from this site, as well as others. I fell like this should be 'easy' but I need to be pointed in the right direction. I'm trying to ...
2
votes
1answer
1k views

How to create a line in a given distance to an existing one?

I am looking for a possibility to create a second line in a given distance to an existing line. The existing line is curved, so simply create parallel line segments with CAD tools will not work. Any ...
2
votes
2answers
634 views

Trimming Specific Text Values in QGIS Field Calculator

Sorry if this is a dumb question, but I am wondering if there is a way to copy the text from one field to a new field, but eliminate specific words. For example: **Old Field** ...