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0

Maybe can you try ogr2ogr -clipdst DATASOURCE destinationFile sourceFile. For example : ogr2ogr-clipdst yourPolygon.shp destinationFile yourPolylines.shp. But, in this case, you will cut one shapefile with another. If you want to cut your polylines shapefile with each features of a polygon shapefile, you must split the polygon shapefile and iterate over ...


0

You may have swapped the coordinates somewhere. If I reproject your resulting lonlat coordinates 103.919768 1.125312 103.690059679 1.35650722603 I get with cs2cs using: cs2cs -f "%%.6f" +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs +to +proj=tmerc +lat_0=1.366666666666667 +lon_0=103.8333333333333 +k=1 +x_0=28001.642 +y_0=38744.572 +ellps=WGS84 ...


0

I actually worked out the answer while composing the questions but I am sure others will get tripped up with this so I decided to continue. The confusion arises because (at least on Mac ) there ate two sets of export symbols: Note pdf is missing from the second row. The ones on the top row appear to export the feature currently previewed. If you click ...


2

It's a already answered question, but I suppose that this could be helpful for the others. I had the same problem and finally ended up writing my own GUI utility. It allows a user to adjust Code Page of input data, rename/remap columns of the destination table, set it's name and primary key. Once imported, the data from the SQL Server can be viewed in ...


0

Check your bit depth. ArcGIS does strange things to rasters sometimes. It may have changed the radiometric resolution of the file.


6

While PostGIS can handle mixed geometry types, this won't help you for QGIS. Regardless of their source all layers in QGIS can only be of a single geometry type.


0

You can join .csv file to your shapefile attribute table by (as you wrote) matching unique identier (ID or something else) add your .csv file to project same way as a layer add your shapefile open shapefile properties (right click -> "Properties") click on "Joins" and then add join via green + button as a layer select your csv file, in join and target ...


1

Please DO NOT use Set CRS for Layer if you want to reproject a vector layer to another CRS. This will corrupt your data, because it does not recalculate any coordinates. Use Rightclick Save As ... under a different file name and different CRS. You better set the layer back to the previous CRS, or delete it and reload a fresh copy.


1

I don't think it makes any sense to try use the raw values from a heatmap in the legend, as they will have practically no meaning to anyone who reads your map. You're much better using descriptive terms in your legend like "higher density" and "lower density". If you REALLY need to use raw values, then it would be something like "0.039 sum of point values ...


1

I had similar problems with an earlier version of QGIS, and solved the problem by storing my data in spatialite databases. The shapefiles I used before seamed to have reached a critical size (not in Gigabyte, but number of features). Especially point shapefiles, like bus stops, which tend to grow rapidly.


2

Apologies if I misunderstood your question but perhaps you could create a new attribute column and calculate the length of each feature from there using: $length Hopefully others will help if I am indeed mistaken.


1

You dont need geoserver or mapserver to serve the tiles. Put them on a webserver and access them with OpenLayers.Layer.GeoWebCache


1

I asked a similar question (Key for a Heat Map) and found the answers very useful. If it does not fully address your question it might point you in the right direction. I also suggest you read the QGIS User Guide section on the heat map plugin (http://docs.qgis.org/2.0/en/docs/user_manual/plugins/plugins_heatmap.html). Good luck with you mapping.


1

I may have found why the call to SAGA:MERGESHAPESLAYERS is not working in ubuntu from QGis Regardless of my 2.0.8 syntax setting QGis generates the following line of shell script shapes_tools "Merge Shapes Layers" -MAIN "/tmp/vlayer_01.shp" -LAYERS "/tmp/vlayer_01.shp;/tmp/vlayer_02.shp" -OUT "/tmp/output.shp" When run it generates the following error: ...


0

Suggest you try building a virtual raster from the DEM TIFFs: Raster -> Miscellaneous -> Build Virtual Raster (Catalog). It seems to work with your sample data. Sorry, I just had to put some hillshade on the result. N.


0

Lowering the marker's alpha channel will make overlapping vertices of the same feature stand out but only after entering editing mode. For a sharper distinction between duplicated nodes than the aforementioned, there is another solution, although it is less practical: Use the Extract nodes algorithm (or Vector->Geometry Tools->Extract nodes from the menu) ...


1

You could try here. They seem to have a lot of shape files that might fit your description. Though the European dataset is in 30 year increments. Your best bet is probably going to have to be recreate it. Wikipedia has some WWI maps in PNG format. As others have mentioned, there are plenty of sites with historical raster maps that you could digitize.


2

It seems that there are two things going on here. First, your tiles are not seamless, in that in the areas of overlap at the edges of the tiles, the elevations are not identical. I can confirm this as I digitized several points along the overlapping area and extracted the elevations in both raster DEMs and found this: In the case of the two tiles that you ...


0

As well as the comment by Mapperz, you may be interested in this thread on the mailing list: http://lists.osgeo.org/pipermail/qgis-user/2014-October/029429.html To sumarise, "this is a side effect of the MDB driver in the GDAL framework" - the developer of that knows about it and is working to resolve it. It may not be a fatal error for QGIS though (as in, ...


0

I also just upgraded to Yosemite, but was also installing QGIS for the first time. I put on the older version of Java supplied by Apple and so far, no problems. I'm keeping an eye out here to see if anyone encounters other issues running QGIS under Yosemite.


0

I ended up using this workflow in Arc.: Buffer road lines by a trivial distance (e.g. 1 Foot) Select the “Dissolve All” options in Arc to merge all overlapping road buffers. Convert multi-part to single part. Convert feature to line. Collapse dual lines to center lines.


0

I gather from a few articles that support for ECW (a highly proprietary format) heavily favours Windows installations: http://www.surfaces.co.il/qgis-on-windows-with-ecw/ I'm not sure how to get the ERDAS support files for Linux, but that's what you'll have to do as noted in the blog post referenced above.


0

Actually the problem was that the raster that I was looking at was loaded from a GRASS database and did not offer pixel size in it's metadata. I then saved the raster onto disk, loaded it, and it did show pixel size.


0

Hm, ok, let's make a proper answer from my comment: Google Fusion allows you to import data from a number of sources, including csv and kml. But as far as I understand, it only understands plain data tables during csv-import. When you exported your geometry as a csv-file, QGIS used the Well-Known Text-Format to represent it in one of your table's fields ...


2

At the moment (and I know it's a bit gross) but you also have to update the layer set on the canvas to update the layer state change canvas.setLayerSet([ml2, ml]) This will also control the render order. m1 will reneder first then ml2 on top of it.


0

You have to refresh the mapCanvas as well: ml.setVisible(True) ml2.setVisible(False) qgis.utils.iface.mapCanvas().refresh() After this the map Canvas will redraw and you can see the changes. Normally you should see changes when you zoom in and out to force a refresh of the mapCanvas manually. To set the layer visibility you can use this: ...


1

It seems your questions are just very basic GIS management operations. If you don't know how to do a select by attribute or export data, you should first read the general QGIS operation manual that explains it. Nevertheless, in order to extract and save, do the following: Have your polyline and point layers loaded in your project table of contents Make ...


1

Ok, I solved. I use Global Mapper instead of GRASS or QGis. There is an option to add elevation data to all vertices from the dtm. Then I exported the vector as a dxf. I still have in Autocad a 3D DXF. Great and easy! :)


-1

+towgs84=33.4,-146.6,-76.3,-0.359,-0.053,0.844,-0.84 is the best i've encountered so far ...


2

The plugin layer has no functionality to export to an image file. Instead, you can save map canvas image (File - Save as Image. A world file is outputted together), and then convert the image to GeoTIFF with the Translate (Convert format) tool of GDALTools. In the tool dialog, the target SRS field should be filled with the CRS of your map (EPSG:27039).


2

You just right click the layer and select Properties. Then go the Metadata tab. Scroll down and look for "Pixel Size".


1

For a visual effect, you can use QGIS's blending options. Create your marker line symbol like you have, with a light colour and on every vertex, and at the bottom of the style tab, put Feature Blending Mode to Multiply (not Layer Blending Mode). Then from a glance, it becomes apparent which nodes are overlapping. In the picture below I have two copies of ...


0

I remember reading that OSM-based layers will print in QGIS at pre-defined scales (see http://wiki.openstreetmap.org/wiki/Zoom_levels). Related to QGIS issue http://hub.qgis.org/issues/5827.


3

Given the forumla: GVF = (x - min) / (max - min) (Notice the brackets.) It is impossible for the values to be outside the range 0 - 1 for all values of x between min and max, which by definition it is. In fact, it should occupy the full range from 0 - 1. So we can conclude that either your min and max values aren't representative of the actual range of ...


3

You are looking for what is called the "strongly connected components" in graph theory jargon. These network islands can be computed in QGIS with the grass plugin - See v.net.components.


1

Boundless has a tool called GeoGig: http://geogig.org/ Users are able to import raw geospatial data (currently from Shapefiles, PostGIS or SpatiaLite) in to a repository where every change to the data is tracked. These changes can be viewed in a history, reverted to older versions, branched in to sandboxed areas, merged back in, and pushed to ...


0

I took the same style values as you, and it looks quite good: but it looks better with a svg symbol. With the standard > I get this: The saved style looks as follows: <renderer-v2 symbollevels="0" type="singleSymbol"> <symbols> <symbol alpha="1" type="line" name="0"> <layer pass="0" class="SimpleLine" ...


2

Given a starting point, bearings and distances the Azimuth and Distance plug-in will do this too.


2

There are a number of sources with examples showing what syntax can be used for rasters. Basically, common mathematical logics are used such as: Mathematical (+, -, *, /) Trigonometric (sin, cos, tan, asin, acos, atan) Comparison (<, >, =, <=, >=) Logical (AND, OR) Here you can find how some of those syntax are used in some examples. Other sources ...


2

You can use the Field Calculator to create a new column and then use a similar command like the following in the expression: toreal("your column") for real numbers. toint("your column") for integers.


1

The plugin Cadinput might be what you are looking for (https://plugins.qgis.org/plugins/CadInput/). See http://vimeo.com/85052231 for a demonstration.


0

Well, this is not the perfect solution, but I created SVG marker with the required symbology. Then I set the needed interval and finally it works how I want!


3

@Martin has provided excellent links in order to create plugins for QGIS. To make life a little easier, there is a plugin called Plugin Builder which very easily creates all the core files you need for your plugin. You can download and install this from the QGIS toolbar: There is also a tutorial here which describes how to use the Plugin Builder ...


2

You could use the Intersect function (Vector > Geoprocessing Tools > Intersect) to provide you with another line layer with where the duplicates lie. You can then give your 2 layers different colours (eg. make the original layer to be thicker and darker; the intersect layer to be thinner and lighter): If you want to see the duplicates in a single line ...


3

I recommend you to read the qgis cookbook: http://docs.qgis.org/testing/en/docs/pyqgis_developer_cookbook/ There you can read how to program a plugin that suits your needs. In the section plugins: http://docs.qgis.org/testing/en/docs/pyqgis_developer_cookbook/plugins.html it is shown how to set up a plugin with a user interface that is using qt


3

I just found a solution. There is also an active psycop2 connection. When I commit it or close the connection before osm2pgsql runs and open it afterwards again it works. Probably osm2pgsql can't access to the database if this connection is open.


0

While it is not possible with QGIS yet it is possible to print layered but not georeferenced PDF files directly from OpenJUMP Plus.


1

To my knowledge Qgis does not currently support the creation of geospatial Pdf's. It can however be done relatively easy using gdal - see this tutorial : http://latuviitta.org/documents/Geospatial_PDF_maps_from_OSM_with_GDAL.pdf


5

This was a tough problem to track down because I had thought that the effect was at the edges of tiles when it fact they are throughout the data. You're right that the phenomena isn't in the data before mosaicking the data. The problem results from the resampling process that is inherent in mosaicking. You need to use either the cubic convolution or bilinear ...


1

Vector -> Analysis Tools -> Distance Matrix will create a CSV output of the distances between each point. You can then select all rows that are 5 or less. Then join your table to your point data, and only points that join are within 5 meters of another point.



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