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5

This is a bit messy thing. You should read at least this GeoTIFF document http://www.remotesensing.org/geotiff/spec/geotiff2.5.html#2.5.2.2 and some GDAL considerations http://trac.osgeo.org/gdal/wiki/rfc33_gtiff_pixelispoint. As a rule of thumb all rasters (aerial, satellite images) use pixel-is-area and measurement data like DEMs use pixel-is-point. ...


4

I would do this in two steps. Firstly add a new field to contain the area of your polygons (see below) give it a basic name such as Area and make the type double (see this for more details). You can then calculate the geometry of your polygons in your new field by right clicking the field heading and selecting Calculate Geometry. Which will bring up the ...


4

If you divide those "strange" latitudes and longitudes by 11930465, you get the North and East degree values you expect: But don't ask me why ;-)


4

First of all, some performance metrics, comparing the two different ways of producing points for a random selection of a million points. create table test (id serial, x real, y real, geom geometry(POINT, 27700)); insert into test (x, y) select random(), random() from generate_series(1, 1000000); update test set geom = ST_SetSRID(ST_MakePoint(x, y),27700); ...


3

Both are common, and neither can be considered entirely standard. For GeoTIFF, both are possible - see Section 2.5.2.2 for the GTRasterTypeGeoKey that describes the interpretation method. The GeoTIFF FAQ suggests using the default (PixelIsArea) value of that tag for compatibility with older versions of GDAL. The World File format uses the centre of the ...


3

You can have your WFS server reproject the data by adding the srsName parameter to your URL (i.e. http://ec2-54-69-8-151.us-west-2.compute.amazonaws.com:8080/geoserver/WRIA9/ows?service=WFS&version=1.0.0&request=GetFeature&typeName=WRIA9:2009BuildingsCOS&maxFeatures=50&outputFormat=application/json&srsName=epsg:4326). Then your ...


2

I clearly don't know the "best" solution between ST_PointFromText and ST_MakePoint. The thing you should notice is that ST_PointFromText and PointFromText are the same function (syntax change due to function normalisation SQL MM). Now, the right ones are ST_* So what you want is something like below (|| are for concatenation) UPDATE points_of_interest SET ...


2

Taking the suggestion by mkennedy for EPSG:28992, the points are located this way: which does not fit well, unless the WGS84 coordinates are rough or wrong. There is also an Amersfoort RD Old projection, but that is far off. Looking closer, the RD New points perfectly match to adresses in Openstreetmap, while the WGS84 are just road junctions; the lower ...


2

Your dataset should appear in QGIS with EPSG:5652. If not, use Set CRS for Layer to get it. The 6-digit CRS is EPSG:25832. Rightclick on the layer, Save As ... under a different name and that CRS, and add it to the canvas. It might be even enough if you just change the project CRS to EPSG:25832, leaving the dataset unchanged.


2

First you will need an iterator to go through your shape files, there are two methods I employ: Method One: a folder full of shape files: import arcpy, sys InF = sys.argv[1] arcpy.env.workspace=InF for fc in arcpy.ListFeatureClasses(): Method Two: a whole tree full of shape files: import sys, os, arcpy InFolder = sys.argv[1] for (path, dirs, files) ...


2

With libtiff you can't get altitude from you file. I spent a lot of time trying to do it with libgeotiff. My advice is to install GDAL. Example: GDALRasterIO( hBand_ , GF_Read , p, l, 1, 1, &pafScanline, 1, 1, GDT_Float32, 0, 0 );


1

I do not know if there is a convention, but coordinates on images normally refer to pixel centres. This this can differ in the case of rasters produced from, for instance, computer models. If you are not sure, you can use GMT, the Generic Mapping Tools, to test you rasters and convert them to some appropriate format, since it explicitly offers the option of ...


1

Just wish to add two things to John Barça's fine answer: First, ST_PointFromText() would be most useful if your coordinate data were already in the form of lines of text like this POINT(xxx.xx yyy.yy) where each xxx.xx yyy.yy were actual coordinates, perhaps as output from another process/system. Going out of your way to add in the text "POINT" is ... ...


1

There is a rule for detection of columns containing coordinates based on attribute name. Coordinate column is detected if the attribute name of X coordinate is: x, xcoord, xcoordinate, coordx, coordinatex, longitude, long or the attribute name contains: x_*, *_x Similar for Y coordinate: y, ycoord, ycoordinate, coordy, coordinatey, latitude, lat or ...


1

You first need to import the CSV and give it which fields are x and y co-ordinates and the projection of your data. This should be the large comma icon which says Add Delimited Text Layer. If you then go to the Vector menu (you may need the Ftools plugin installed but this comes as standard in recent versions of QGIS I believe) then Analysis, you have a ...



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