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7

There's a good answer over at Stack Overflow, which goes a little something like this: The geography type is a little bit more restrictive than geometry. It can't cross different hemispheres and the outer ring must be drawn counter-clockwise. The rest can be found here. Another article goes into some more detail: If you’re looking for the ...


4

Maybe check out the properties of Projected Coordinate Systems, to get a view into their utility? There are 3 aspects or properties presented in Projected Coordinate Systems that establish their utility and rationale. Any projection of 3D space on a 2D surface will of course exhibit distortion versus reality. Depending on your application, using a specific ...


3

Assuming you have an ASCII XYZ file with SRTM-like data loaded to the canvas: go to Raster -> Projections -> Warp (Reproject) select your input file (if not alredy selected) Unfortunately, gdalwarp can not write XYZ raster files, so we use a vrt file for intermediate saving select an output file test.vrt (format .vrt) Set Source SRS to EPSG:4326 ...


2

If you load the file, the CRS should be assigned automatically. You can check that with Rightclick, Set CRS for Layer. If not, create a custom CRS with the proj string you mentioned under Settings -> Custom CRS. Then rightclick on the layer, Save As ... under a different file name, Select CRS and navigate to a lat/lon CRS from list.


2

After looking in the API docs at http://openlayers.org/en/v3.0.0/apidoc/ol.source.GeoJSON.html and unchecking the checkbox Stable Only on the top right of the banner, I see a projection option for the source. It's here you have to set the projection to say to OpenLayers 3 to transform the data coordinates. Trying changing your fiddle with below part, it ...


2

The value k = 0.0818191908426 is referred to as the First Eccentricity of the Earth. This value is used in equations to convert between coordinate system values of position, such as lat-long-alt to ECEF coordinates.


2

Traditionally, topographic maps are plotted using a conformal projection, not an equal area projection. A conformal (or orthomorphic) projection preserves angles and, at any point, has isotropic scaling. Such qualities allow relatively easy computations involving angles and distances. en.wikipedia.org/wiki/Map_projection#Conformal ...


2

The above code looks more like you just clone shp into shputm and then assign the output of crs(shp) to shputm without performing an actual reprojection. Anyway, if you import both the shapefile and the NDVI raster, and then reproject shp using spTransform, subsequent data extraction should work out fine. Also, the output of extent(shp_utm) roughly agrees ...


1

Apparently my underlying assumption of expecting a 3m drop over 40km was incorrect. I had taken an answer I found stating that the earth dropped off by .078m over 1km, and I attempted to apply it linearly over 40km. But due to the nature of this problem, the drop over 1km does not linearly scale as the geodesic distance increases.


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At the end I used the shapefile from the National Land survey of Finland even though not perfect, they seemed to be of a higher quality


1

One of the most overlooked aspects of transforming coordinates from NZGD1949 to NZGD2000, including NZMG1949 to NZTM2000, is that it should use a transformation method. There are three methods: 3 parameter similarity, with 5 metres nominal accuracy 7 parameter similarity, with 4 metres nominal accuracy Distortion grid, with 0.1 - 1.0 metres nominal ...


1

I was actually trying to do the same thing except with the OH south state plane grid and I came across your question. I was getting wrong results with 3735, now I get correct results with 3729. I expect if you change from 3734 to 3728, you will get the correct results. EPSG:3728: NAD83(NSRS2007) / Ohio North (ftUS) EPSG:3729: NAD83(NSRS2007) / Ohio South ...



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