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5

Because you are "near" the equator, the cylindrical projections (like Mercator) work well (not too many distortions). If you want to be perfectly fair in terms of areas, you could use cylindrical equal area or sinusoidal projection. But this would not markedly differ from Mercator.


3

The Mercator projection, is a conformal map projection so any angles measured on the map are the same as if measured on the globe. It also has the property that all straight lines on the map represent loxodromes, or lines of constant azimuth. Those are useful properties in surveying and navigation. Beyond that, however -- and especially when mapping very ...


3

This set of extracts from OSM data may be what you're looking for. In particular, this shapefile of the coastline around Helsinki.


3

Two common cases: If you created the shapefile you will have to use the Define Projection tool to define the projection/coordinate system. If you downloaded the shapefile: Shapefile has spatial reference (nothing technically you have to do here, should load and re-project on the fly in ArcMap) Shapefile is projected, but no set spatial reference (look ...


3

What's happening is that the data you are trying to insert does not have an SRID assigned. To assign one, try wrapping the inserted geometry in your insert statement with ST_SetSRID(). E.g., INSERT INTO public.borne (num_borne, shape_borne) (SELECT num_borne, ST_SetSRID(shape_borne, 26191) FROM public.sometable); or INSERT INTO public.borne ...


2

The problems arise because the CostDistance calculations use the (Euclidean) distance in a map as a surrogate for the true distances experienced on the globe's surface. This surrogate will be distorted in two ways: The relationship between map distance and globe distance will vary according to location on the map. At any given point, the map-globe ...


2

When you say that you have imported your CAD drawings into ArcGIS, I am assuming that you now have either file geodatabase feature classes or shapefiles. Consequently you should be able to perform a spatial adjustment transformation on them: Transformations move or shift data within a coordinate system. They are often used to convert data from unknown ...


2

Orthographic projection is able to show the poles, which mercator can not do. Furthermore, the projection looks like the view from outer space, which feels kind of natural. It only shows half of the worlds surface, but that's what you see from outer space. An even more "natural" view would have resulted from a perspective projection, which looks like the ...


2

Yes, as whuber says, the gnomonic projection is the way to go. GeographicLib (written by me) includes an ellipsoidal generalization of this projection in which geodesics are very nearly staight. For example, if you consider two points 4000 km apart, the straight line connecting them in the gnomonic projection deviates from the geodesic by less than 30 m. ...


2

Do the computations using the Cartesian formulas in a Gnomonic projection. These projections cover a single hemisphere and map all portions of great circles to line segments. Presumably, in the representation of your spherical polygons as sequences of (lon,lat) values it is implicit that each successive pair of vertices is to be traveled along a geodesic. ...


1

I have constructed below a well-known text (WKT) file for the projected coordinate system that your data is using. You should copy it to a text file that has an extension ".prj". The WKT string must be a single line. Put the text file into your ArcGIS installation folder, then "Coordinate Systems, Projected Coordinate Systems". When you want to project your ...


1

I believe what you are experiencing is more or less a copy of this question. The coordinates in the rainfall data are in longitude/latitude, but with values ranging from 0 to 360, instead of -180 to 180 (as your political boundaries are). See the GPCC spatial note here (emphasis mine): Spatial Coverage: 0.5 degree latitude x 0.5 degree ...


1

Given your examples above, you must be using "Nearest Neighbour" option to do the resampling in the Project Raster tool. That's why some values "disappear". What else can it do, it takes the nearest value (measured by cell center position) and assigns it to the new cell in the new coord sys. A histogram of the cell values between the old & new can never ...


1

Web Mercator has only real metres as units close to the equator. The more to the poles you come, the more x and y distances get apart. You should better use a "good" projection like the UTM zone of your area if you want to see the lines in correct length.


1

The error is not on your side, but on Google's side. See http://alastaira.wordpress.com/2011/01/23/the-google-maps-bing-maps-spherical-mercator-projection/ http://www.hydrometronics.com/downloads/Web%20Mercator%20-%20Non-Conformal,%20Non-Mercator%20(notes).pdf They claim to use a sphere (a=b), but really use the WGS84 ellipsoid (a>b) lat/lon coordinates. ...


1

Your problem is that WFS 1.0.0 does not support reprojection of the coordinates. If you switch your request version to 1.1.0 then GeoServer will take your srs into account.


1

You'll need to define both a horizontal coordinate system (could be projected, like UTM) and a vertical coordinate system (like NAVD88, making sure to be in the same units as your horizontal). A vertical coordinate system expresses elevations relative to a baseline, usually a mathematical representation of the Earth's surface. Your measured elevations ...


1

If you think of accuracy of distance measurement, mercator or transverse mercator with lat_0 and lon_0 set to the center of your area will do fine. Mercator has true lengths along the latitude, while transverse mercator has them along the meridian. So it depends on the format of your area which one is better. You can use omerc if you need a rotated grid.


1

I think you need to specify the srs parameter of your layer: srs : '32024' //NAD27 or srs : '32126' //NAD83


1

As far as I know this is not supported. Ask from geoserver-users mailing list first and make a feature request to Geoserver jira because it feels like a useful addition. Meanwhile you can use the standard OGC filter instead <Filter> <Intersects> <PropertyName>the_geom</PropertyName> <gml:Point ...


1

Funnily enough I have just answered a similar question a couple of minutes ago. Calculating a circle in Lat/Lons This link will take you to a page that has describes algorithms for calculating forward azimuths, which is the type of calculation you have described in your question. I don't know if it will have all of the details you need but it should get ...



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