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5

The effect that you are seeing is called Anti-Aliasing. When ArcMap draws a jagged Line, It will draw all pixels. When QGIS draws a jagged lines, it makes the outer pixels of a color with lower intensity, which gives a smoother appearance. Unfortunately, there is no option to enable Anti-Aliasing in ArcGIS desktop. You should upvote these two idea for ...


5

File Geodatabase in QGIS 2.4 Note: Use Directory rather than File Once the file geodatbase is loaded save the shapefile


4

You can right click with a Mac, hold 'ctrl' and click. Or use two fingers to tap on the touch pad, or plug in a mouse with two buttons. When you do that, you right click your layer (that has selected items) and choose 'save as' then check the box 'save only selected features.'


4

Buffer the lines. Use Difference to subtract the buffer polygon from the original polygon (p0).


4

Reiterating the comments as an answer for the convenience of others: Always make sure that each layer has a unique shapefile associated with it, otherwise data losses will be likely if more than one layer is based on the same shapefile and you edit its attributes.


3

To use the GRASS tools directly, you need to first import the data you want to work with into a GRASS database. If you use GRASS algorithms through the Processing toolbox, you can skip this importing step because Processing takes care of all the data conversion. It's therefore much more convenient. You don't have to explain to your students how GRASS works, ...


3

Yes, there is a Flicker group. See also, the Screenshots page on the QGIS.org site for latest samples of maps. Not sure about the Chugach State Park map. Generally, the splash screen map is of a specific area, but not necessarily produced with QGIS.


3

Yes. It does as it appears from looking at the source code for the Spatialite Data Provider. The QgsSpatiaLiteFeatureIterator class is the one that supplies the features to the map upon sending a rectangle extent. You can just search for 'spatialIndex' in that class to see they actually use the index if available.


2

You may need to tick the "control rendering order" option at the bottom of the layers panel.


2

You experience the limitations of the csv driver. Saving as shapefile and working on with that is really the best opportunity. For the data type issue, you can create a csvt file to predefine the data type of the columns: http://www.gdal.org/drv_csv.html http://anitagraser.com/2011/03/07/how-to-specify-data-types-of-csv-columns-for-use-in-qgis/ You have ...


2

You can build queries by using the Query Builder or an alternative is to use the Expression string builder (Layer Properties > Style > select Rule-based > add a rule > insert your command in the Filter box or click the '...' button to bring up the string builder interface. In both cases, I do not think QGIS supports the comments function when creating ...


2

They are still there in 2.4, they've just been renamed and moved slightly. "Feature Filtering" is now "Filter With" and uses the one-line filter from the attribute table. "Feature Sorting" is now just "Sort by" and is just below the file name expression.


2

Just add another attribute to the vector layer's attribute table and fill it with the value using Field Calculator. For help with the field calculator, please check the docs: http://docs.qgis.org/2.2/en/docs/user_manual/working_with_vector/field_calculator.html Note that QGIS does not support 3D geometries so you have to store your z value in the attribute ...


2

The shapefile from Natural Earth contains the south pole. The Mercator projection is not able to render that point for mathematical reasons (it would be in inifinity). What you can do: Set Project CRS from Layer (that would be EPSG:4326) switch to edit mode Delete the bottom line of the antarctic save the layer Change Project CRS to EPSG:3857 If you ...


2

I assume two things causing your described error. Make sure you chose the right in- and output coordinate system. If the input image has a wrong coordinate system the output is adjusted according to these distorted information. Try to distribute your control points over the whole image. Additionally, if they are too close smaller inaccuracies have a larger ...


2

Assuming you just want the general orientation of the polygon, rather than a specific segment... try the Minimum Bounding Geometry (Data Management) ArcGIS tool with the RECTANGLE_BY_WIDTH or RECTANGLE_BY_AREA geometry type and the MBG_FIELDS option. The MBG_FIELDS option will add the following fields to the output attribute table: MBG_Width—The ...


2

My solution is to digitize the boundaries one after each other, using a snapping tolerance of 10 pixels to fetch the vertices of the existing polygon. Another option is to use the polygonizer: How to go with...somewhat complex geological maps in QGIS?. It combines lines to polygons in an automated way.


2

Do not use Set CRS for Layer if you want to reproject your data. It changes only the CRS definition, but does not recalculate any coordinate. So set it back to what it was before (WGS84 I assume), and use Save As ... under a different name and different CRS.


2

One option that may be a bit faster (less clicks) or you could call from a script would be to use ogr2ogr command (using OSGeo4wShell (which comes with installation of QGIS)). ogr2ogr -f "ESRI Shapefile" C:/Temp/Shps C:/Temp/test.gdb If you want to export out a subset you may use the same command above but at the end list out the table name(s) (e.g. ...


1

myVectorLayer = QgsVectorLayer("polygon", "mypoly", 'ogr') does not create a valid vector layer, therefore mySymbol1 = QgsSymbolV2.defaultSymbol(myVectorLayer.geometryType()) does not return a valid symbol and causes the error you see. Replace "polygon" with a valid file path.


1

I may have a solution for you. If flow in one direction is consistently lower than in the other direction, this would work. I think you have much of the answer included in the question. I would attempt to duplicate the layer and draw the limited flow on top of the greater flow and have them both symbolized by the flow value.


1

It's possible in the current development version of QGIS (which will eventually become 2.6 - there's instructions on how to obtain development snapshots here), and a potential workaround is available in 2.4. Both methods are done by checking the "Filter with" checkbox under the table's "item properties" tab, and entering a filter expression. In development ...


1

Not currently - there's some outstanding feature requests for this: http://hub.qgis.org/issues/10273 http://hub.qgis.org/issues/8006


1

Looks like you want a Mercator Projection. Try to save-as your shapefile assigning the WGS 84 / Pseudo Mercator (EPSG: 3857) projection or assign this projection to your project (using transformation on the fly). See also: What is the standard Mercator projection?


1

To check the number of points per grid cell from a LIDAR point cloud in GRASS you can use the r.in.xyz module. This module creates a grid from the point cloud using a "method" parameter by which you choose how to aggregate the points when importing. If you choose method=n then the resulting raster will contain a count of points for each cell. By setting ...


1

Go for print composer. Increase the page size and resolution. Add the map and if you want to create a map of the whole world, make sure you zoom to full extent. Then save as image. If the size is not big enough, increase the paper size further. A0 with 300dpi should easily be possible if you have enough RAM.


1

If you have georeferenced images, you can use Raster -> Miscellaneous -> Build Virtual Raster or Merge to make a single raster from them. The first one does not even create large files. If you have finished adding images, you can still export to geotiff.


1

I'd suggest to poligonize the grid and to then intersect the polygon grid with the other input polygon layer. That should be much less trouble.


1

The mmqgis plugin is a bit more comfortable than the delimited text import. You can read from csv, and choose whether the result should be points, lines or polygons. EDIT The source data you now added to your question looks pretty much like Openstreetmap format. So you can add it using Add Vector Layer or the Openstreetmap plugin, part 2 and 3. Part 1 ...


1

The distortion is caused by your selection of target SRS, and the CRS you are using in your QGIS project. As soon as you are using a different CRS in QGIS as the one used to create your the raster (jpg file), you will see this distortion. This normal behaviour. If you're setting the same CRS to the QGIS project, the image shown will resemble your original ...



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