Questions tagged [projection-mathematics]

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31 views

Web Mercator square and not 1x2?

I can not understand why Web Mercator projection is strictly square. In my mention: We have a planet as a sphere. We have 360 degrees of longitude and only 180 degrees of latitude. That means if we ...
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1answer
26 views

How to check for PostGIS Function Support Matrix for new custom EPSG imported from EPSG site

I need a support for CRS that was not available in PostGIS 2.5 so I looked up into the EPSG site they had simple easy straight forward insert query to add EPSG so I did that now how do I check or know ...
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1answer
334 views

Whats the name of this projection?

a) Whats the name of this projection? Source:http://www.viewsoftheworld.net/?p=5737 b) Is it possible tu use this projection in qgis?
1
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1answer
39 views

Calculate Coordinates on the Beeline between two Coordinates on a Spheroid/Ellipsoid (Earth)

I have two coordinates of locations on the earth and want to calculate points in between these two coordinates on the Beeline, for example the coordinate in the middle or at 10%. I am able to do this ...
2
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0answers
41 views

Is there a difference in using Haversine distance vs re-projecting coordinate frame?

I have a GeoTIFF raster file in the EPSG 4326 (WGS 84) geographic coordinate system. I want to crop a 20 km x 20 km square around a particular (lat, long) coordinate, and save that as a new raster. ...
3
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1answer
88 views

Procedure of transforming coordinates?

I'm trying to understand the math behind this transformation. I should note that I've been able to perform the transformation using GeoPandas, but I'd like to understand what is going on under the ...
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0answers
16 views

Transformation from Sphere_Natural_Earth to WGS1984

I have a set of files that are stored in Tom Patterson's Natural Earth Projection, and I would like to convert them to WGS1984. This will require a transformation, but I can't locate one and don't ...
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0answers
23 views

Correlation between varying bearings

Problem: The Bearing of point B from point A on one datum and projection varies from that on another datum and projection. Can a consistent correlation be established for the variation in the Bearings?...
3
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1answer
244 views

Projecting points on line and calculating distance from line start

I have a vector layer with a number of points which correspond to magnetic targets axis retrieved from AutoCAD The task is to project the points on the axis and then calculate the distance of each ...
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1answer
67 views

What parameters do azimuthal and transverse cylindrical projection in secant case have as proj4 string

conical equal-area projection, secant case has e.g. +proj=aea +lat_1=... +lat_2=... +lon_0=... +lat_0=... +x_0=... +y_0=... etc... I would ask if there is such thing, for transverse cylindrical ...
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0answers
28 views

Will I get the same area results using different equal area projections in QGIS?

If I want to calculate areas with $area in QGIS in metric units (sq. unit) of a vector layer containing polygons represented in WGS84 lat/lon, I must reproject the layer onto an equal-area projection. ...
5
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2answers
181 views

Geometric difference between equal-area and conformal projection

For simplification, let's have a source light for a map projection. I know where to put the source light in order to get an orthographic, stereographic, gnomonic map projection, but I still don't ...