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1

You may check out the 'Trace Downslope Flowpaths' tool in Whitebox GAT. It will identify the cells in a DEM that receive flow from upslope target cells. It is however based on the D8 flow algorithm and therefore cannot model flow dispersion, which would yield downslope 'areas' as you are referring to them as. Nonetheless, there is some debate in the ...


0

If you want a GUI for pgRouting, you can install the pgRoutingLayer plugin for QGIS. It provides a GUI to access pgRouting functions to compute routes. The routes can be displayed and exported to QGIS layers which you can manipulate and analyze any way you want. You can see the plugin in action in the following screenshot (panel on the right). The plugin ...


0

Some if not all ftools tools have been ported to Processing. You should find Create grid in the toolbox.


0

Our RW Net 4 library can handle your three needs, from either QGIS (python) or MapInfo, with MapInfo being somewhat easier. But it isn't open source and I hope it isn't confusing.


2

It is the obscurity of Pseudo Mercator that leads to the offset. Both projections (3857 and 54004) share the same WKT definition, but it is treated differently. Google (Pseudo) Mercator takes lat/lon coordinates of the ellipsoid, and uses them as they were on a sphere. Hence the different definitions a=b= 6378137 in the proj string vs SPHEROID["WGS ...


1

If I understand your question correctly, you can achieve this by using the Distance to nearest hub function via Processing Toolbox. Select the required options (first image), and choose what measurement you want the distance to be calculated in which will be added into a new column. You can repeat this step to then calculate the centre of each cell to the ...


4

The syntax is almost correct (see the note in the end), but you might be using it in the wrong place. The correct way of doing it is like this. Label your layer using your "Column Y" field, in the example below that's field "codigo". go to the "text" sub-menu, color and click the data defined button; There choose the edit... option below Expression; ...


0

If I understand the question correctly, the QGIS Raster Calculator will do what you want. For some examples that touch on your problem see: http://spatialgalaxy.net/2012/01/25/using-the-qgis-raster-calculator/ I think you would then clip the output raster using your flood polygon. N.


2

The postgres provider requires integer datatypes (i.e. ones, that are internally handled as QVariant::Integer or QVariant::LongLong) Integer: int2 int4 LongLong: int8


1

The quickest solution might be to copy the style file, open it in a text editor and find and replace the column names.


1

I've run into this same problem in the past. I'm sorry but I don't use QGIS very often so my answer is going to use Whitebox Geospatial Analysis Tools and I'm sure you can find the equivalent tools in QGIS to perform the same task. The basic idea is to interpolate a flood surface based on the elevations from the DEM that coincide with the perimeter of the ...


0

Thanks for the links, I had a little look through them. Unfortunately, there's not a lot of common attributes between these 2 shapefiles to get a decent enough result. For example, simply using the JOINS option on the name columns CEO_CODE13 and SA2_NAME11 would only give you ~67 fields in the attributes table. Personally, I would spatially join the layers ...


1

SOLVED: I was convinced that the raster was in EPSG:3003, but actually it was not! The raster layer was coming in as EPSG:4326 from the map server, even though I had set it to 3003 in the layer property (see screenshot). This is where the problem came from and all my other layers had the same problem. So I have now specified a new layer source, being sure ...


2

If you use the Openlayers plugin inside QGIS, you have to set the project CRS to EPSG:3857, not EPSG:3003. 3003 is for Italy only, but the Openlayers plugin is worldwide. The other layers may still have other CRS.


1

You can use the classQGSCredentials to set and get credentials: http://qgis.org/api/classQgsCredentials.html


1

I have managed to figure out how to achieve this but I don't know if this is the best way to do this. I used Rule-based styling, screenshots below: And then I individually set the sizes of svg marker for each "category": And this is what it looked like in my canvass: Unfortunately, I don't like the results I have in print composer: I've read a ...


2

You could calculate a buffer (not more than 5 meters) for the start- and endpoint of every linestring. Then, intersect the buffer with the road network. A line that doesn't intersect with the buffer is likely to be a "correct" unconnected road. However, you'll have to play with the buffer radius for satisfactory results.


1

You can set up the initial colour ramp and then change each symbol and range manually by double clicking on it.


1

I like DigitalOcean as a host, it's really cheap, like, $5 per month. Super simple web-interface for starting machines, you can add SSH keys to make it secure, it's just right for testing VMs. I have no affiliation with DigitalOcean. I can give you $10 referral credits. (Disclaimer, I get something out of it if you continue to use it, see here.) Once you ...


3

It's not currently possible (as of version 2.4). It's a valid request though - you should file it over at http://hub.qgis.org/issues


0

Assuming your LiDAR .asc file is a bare-earth model, use the plugin Raster based terrain analysis. Set the analysis as "Slope". From QGIS 1.8 documentation: Slope: Calculates slope angle for each cell in degrees (based on first order derivative estimation). To calculate the slope on each cell of the raster it uses a 3x3 cell grid (the 8 neighboring ...


0

Put this end of you code last line: QgsMapLayerRegistry.instance().addMapLayer(vlayer) If it also is not working. You probably unchecked the Render off in bottom status bar just after where co-ordinates shown:


4

No the API is fine what is happening is Python is seeing \n and treating it as a new line which is what \n means. You will need to put a r in the front of your string. (r"c:\yourpwth")


2

ARCGIS shapefiles don't contain EPSG codes, only WKT definitions, so QGIS has to make a guess which one from its own EPSG database fits. In your case, it does not succeed, maybe due to rounding errors for x_0 and y_0. In WKT, they are in feet (like the coordinates), while the proj4 string always uses metres. You can open the .prj file from ARCGIS and ...


1

I suggest that you replace the .prj of your shapefile (same name as the other files ) with the prj from Spatial Reference site, which seems to be correct. The difference in X and Y northing comes from the conversion in feet. Probably this is a rounding problem for the two WKT. PROJCS["NAD83 / California zone 3 ...


8

Maksim already provided the answer with ArcGIS, so here is the (very similar) QGIS solution right click on your shapefile to open its attribute table click "toggle edit mode" button (a pencil) (or ctrl+E) on the right, click the icon for field calculator (an abacus) (or ctrl + I) write sqrt(name_of_field) Note that you can check "create in a new field" ...


4

Using Field Calculator, either VB Script Sqr([FIELDNAME]) or Python math.sqrt(!FIELDNAME!) under the Number Type will yield square roots. You can either calculate into a new field, or on the field itself.


1

The elevation service on ArcGIS Online includes ready to use worldwide data, and also a built in raster function to generate aspect. It's also pretty simple to filter simultaneously for a range of aspect values (290-250 degrees) as well as elevation (e.g. 0 to 10 meters, depending on how you define a beach - or perhaps you already have the beaches ...


0

Supposed you are using QGIS: Project CRS must be EPSG:3857 when youn intend to use the Openlayers plugin. The layer CRS may have other CRS, as long as On-the-fly-reprojection is enabled.


1

You need to digitize the boundaries (assuming a search online has drawn a blank for any existing datasets - that would be my first port of call! EDIT - On that note, I just found this link which may be worth a look). To digitize the boundaries, there are several approaches you can use but I would start by creating a line-dataset that represents the ...


1

Unless the borders are coloured in a unique colour, you have to digitize the borders as polygons manually. There is no tool that can digitize monochrome line patterns if they lay over other map objects of the same colour like roads and rivers. Make sure that your boundary polygons snap to each other. I use a snap radius of 10 pixels (not Map units!) for ...


7

In the field calculator select "update the column" where you have numbers and use this string "COLUMN_NAME" || ' M' If you just want to label them with the 'M' paste the same code in the "expression based label panel".


3

Shapefiles have no type MultiPolygon (type = Polygon), but they support them anyway (all rings are stored in one polygon = list of polygons, look at GDAL: ESRI Shapefile) It is easier with Fiona and Shapely: import fiona from shapely.geometry import shape, mapping # open the original MultiPolygon file with fiona.open('multipolygons.shp') as input: # ...


4

from GDAL mailing list using python import os from osgeo import ogr def multipoly2poly(in_lyr, out_lyr): for in_feat in in_lyr: geom = in_feat.GetGeometryRef() if geom.GetGeometryName() == 'MULTIPOLYGON': for geom_part in geom: addPolygon(geom_part.ExportToWkb(), out_lyr) else: ...


-1

Try opening your .prj files in a text editor (Notepad, Notepad++, etc.) and then check out the text there. If the CRS saved correctly it should say: PROJCS["NAD_1983_StatePlane_Texas_Central_FIPS_4203_Feet", GEOGCS["GCS_North_American_1983", DATUM["North_American_Datum_1983", SPHEROID["GRS_1980",6378137,298.257222101]], ...


2

Instead of Intersect, use Clip. Vector > Geoprocessing Tools > Clip


0

Exkoria, I know you're using QGIS, but I figured I'd post this code from ArcMAP in-case you can get some help from it. It pans to each feature in a shapefile and exports an image, and then repeats for all features in the shapefile you specify. Like I said, its not QGIS, but it might help somehow. # This script pans ArcMap, once for each feature in Layer ...


0

I don't know how it is working but these piece of code works. vlayer = QgsVectorLayer("home/sanjayr/Desktop/india-latest.shp/buildings.shp","sanjay","ogr") QgsMapLayerRegistry.instance().addMapLayer(vlayer)


0

geocat offers a commercial ArcMap plugin called 'Bridge' that can convert all of your ArcMap symbology to SLD (there is an open source alternative arcmap2sld). In QGIS you can import SLD and use this as style for QGIS layer. In bridge the tree structure of the TOC is exported as WMC, and the data as shapefiles (including metadata .shp.xml) and tiff's. I ...


2

Judging from the coordinates we can see on your second screenshot (-99,30), I think that you changed the layer CRS in layer properties instead of properly reprojecting the data to state plane. Reproject the layers and try adding the scale bar then.


3

if not availble you can always create your own convertion function: http://nathanw.net/2012/11/10/user-defined-expression-functions-for-qgis/ and should be good to share it in some place or to propose to insert in the expression library


2

Kadeem's modified answer will prevent your features from being visible, but they will still be present, if you are trying to identify an individual ship track you may click an invisible feature by mistake. What it seems like you need to do is define your layer so that it's as if those features don't exist. In ArcGIS this would usually be done using a ...


0

Perhaps use the Spatial Query to select all lines that intersect or touch or overlap other lines. Then could you invert the selection (to select all lines that do not intersect, touch or overlap) and delete the lines? Perhaps the topology checker could work to help you select or identify lines not touching other lines.


3

Open the "Layer properties" and go to the "Fields" tab. You will see a column "Alias". Whatever you enter there will be used throughout the user interface.


2

Yes you can do it with fewer values, depending on the combinations you want of course. In the Data Defined Properties section, click on the curly E button to define an expression. When the Expression dialog box opens, you will probably want to define a conditional expression. Use the CASE ELSE option and create an expression something like this (for the ...


1

I'm not sure if I understand you correctly but if You're trying to translate english names of columns into your local language automaticaly I think you can't do this in QGIS. The only resolution that I mind is creating a view on database and show this view in QGIS Create view translated_table as select id as translated_id, field2 as ...


2

I haven't tested this but perhaps this might help: Settings > Options > Locale EDIT: The only other method I can think of is: Add Vector Layer > Encoding And select whichever one you think is suitable. Hope this helps!


0

The open-source GIS Whitebox Geospatial Analysis Tools has a tool called Extend vector lines that can be used to perform this task exactly. From the help documentation: This tool can be used to extend vector lines by a specified distance. The user must input the names of the input and output shapefiles, the distance to extend features by, and whether ...


0

Based on your comments, the problem is solved. In summary: 1-Using the excel tool, here, Excel tool for converting LatLong to UTM. In the Batch Convert LatLong to UTM sheet, paste the LatLong coordinates into collumn L, M then, the UTM coordinates are automatically calculated and save in AE,AF collumn. Saving the UTM coordinates to a file. (This step also ...


1

This One has step by step tutorial. Hope you like it. QGIS http://www.qgistutorials.com/en Quickstart Making a Map Working with Attributes Importing Spreadsheets or CSV files Using Plugins Searching and Downloading OpenStreetMap Data Basics GIS operations Basic Vector Styling Calculating Line Lengths and Statistics Basic Raster Styling and Analysis ...



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