# Questions tagged [cartesian]

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### How can Cartesian and ellipsoidal perimeters and areas be so different in an EPSG:3857 layer?

For a particular polygon of mine in a "EPSG:3857 - WGS 84 / Pseudo-Mercator" layer, the derived measurements QGIS reports are: Ellipsoidal perimeter: 1015 m Cartesian perimeter: 1218 m ...
• 183
60 views

### Transformation needed for placing cartesian coordinate rectangle on map using geographical coordinates

I have come across a requirement to convert rectangle image with specific width and height to geographical coordinates so that it can be placed on map. I have all the four geographical vertices for ...
136 views

### Generating 3d points from GeoTIFF using libgeotiff and proj

I'm working on a C++ library where I need to ingest several different DEM formats (such as GeoTIFFs, SPC Maplets, and some other internal formats) and convert them to a 3d triangular mesh. In the ...
• 111
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### Converting point coordinate from local Cartesian to WGS 84 in QGIS?

I need to convert some cartesian (x,y) meter points coordinate from an origin to WGS 84 using QGIS 3.x API. I have the lat and long of the origin: lat is +44.0 lon is +9.0 degrees. I try to make a ...
• 31
1 vote
55 views

### Map projection from latitude/longitude to cylindrical system [closed]

I have some questions about projections. First of all, I would like to plot some positions on a x-y grid, graduated in km from latitude/longitudes coordinates. Is this conversion relevant: https://en....
45 views

### Is order among distances preserved when using Geodesic and Cartesian distances?

Let's say I have a set of points and I need to know which of them is the closest from some reference point. I also need to know the geodesic distance to it. Can I first calculate Cartesian distances, ...
1 vote
249 views

### Measuring distance using QGIS

Normally if you measure the distance of line and polygon in Cartesian is smaller compare to Ellipsoidal in QGIS. However, when I am measuring the distance Cartesian system gives greater value compare ...
• 55
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### Extent of a proj4 string

I have a custom proj4 string in which my data is represented in Cartesian local coordinates. The example proj4 is below. +proj=tmerc +lat_0=44.155877943 +lon_0=141.655514872997 +k_0=1.000004976 +a=...
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3k views

### Converting Velocity ECEF to NED or LLA/Geodetic

I'm able to get a correct position from ECEF to Geodetic to NED with a relative footpoint and can verify using online conversion tools: https://www.oc.nps.edu/oc2902w/coord/llhxyz.htm https://www.ngs....
1 vote
90 views

### Horizontal coordinate adjustment using EPSG 9621 operation method in PostGIS

We have some Cartesian coordinates which needs to be applied with similarity transformation. The transformation operation method describing how to do the same is explained in EPSG 9621 method. How to ...
• 180
1 vote
321 views

### Reprojecting OSM vector Data in UTM32N EPSG:32632

Unfortunately my QGIS doesn't really want me to change the Projection of the OSM Vector data. I downloaded processed Vector OSM Data which was in the (normal) Mercator Projection. I put the layers in ...
433 views

### How to convert NAD83 coordinates to Cartesian coordinates expressed in meters?

I have coordinates (longitude, latitude) expressed in NAD83 and I would like to be able to convert them to Cartesian coordinates (X [m], Y [m]) in order to use them for modeling. A similar topic deals ...
3k views

### Getting accurate distance measurements using EPSG:3857 in QGIS

I'm still a beginner at QGIS and am currently using it to plan trap placement for an upcoming fieldwork session in Central Europe. Traps should be placed along a transect 100m apart. So far when I ...
• 31
1 vote
468 views

### Calculate the area of a polygon on the surface of the Earth

I'm trying to write a function that will accept an array of coordinates and calculate the area of the polygon. function getArea(lat_long: Array<LAT_LONG>){ lat_long.push(lat_long[0]) const ...
1k views

### What is the projected coordinate system equivalent for ETRS89?

ETRS89 (EPSG: 4258) is the EU-recommended frame of reference for geodata for Europe 1. This coordinate system is geographic. However, in the software world, we need to transform it into a projected ...
1 vote
661 views

### How to calculate corners of a rectangle based on Cartesian coordinates

I would like to draw a rectangle based on a center point lat and lon assuming a given length and width, let's say 4.5m and 1.5m, respectively. I guess, we need the bearing too. I've made a simulation ...
• 11
3k views

### Convert x, y, z local points to WGS84 having only 3 coordinates known

I have a set of (x, y, z) points on a local coordinates system cartesian plan. For only 3 of these N points, I have the corresponding WGS84 coordinates (latitude, longitude and altitude). How can I ...
• 23
1 vote
129 views

### Gauss-Krüger system to Unity cartesian Coordinate Conversion

I have to deal with coordinate conversation into my unity (a game engine which uses cartesian co-ordinate) project but I am zero in this field as it is involved math, geometry, and geography with lots ...
176 views

### Why are topocentric coordinates of point A relative to point B not strictly the negative of the topocentric coordinates of point B relative to point A

I just tried to play around with some geodesy lately, using CartConvert in bash: \$ echo -43.4242920E -22.9145118N 0 | CartConvert -l -43.7954220E -22.7454621N 0 38072.841396 -18768.489365 -141.336023 ...
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237 views

### Resizing objects from Cartesian measurements to Ellipsoidal

I have been working on a project in QGIS 3.12.2 in EPSG 3857 so it works with google earth. Without realising the difference there would be between cartesian and ellipsoidal I buffered some points. By ...
• 21
174 views

### Getting displacement in meters from "XYZ ECEF" or "NMEA" data

I am new to this field. I am working on a GNSS receiver that gives me live location data in NMEA and XYZ ECEF format. The receiver is mounted on my rover and I wish to use this data to get the rover's ...
• 101
1 vote
214 views

### QGIS DXF measurements in AutoCAD are in Cartesian and not Ellipsoidal

I'm trying to export some land boundary polygons to AutoCAD using the Export to DXF function. The issue I am having is that the distance measurements in AutoCAD, of the exported DXF file, represent ...
• 11
1 vote
442 views

### Map from video game with Cartesian coordinates in Mapbox GL JS

I want to create an interactive map in the browser from the RPG video game. I think I'm quite experienced in both backend and frontend development, so this is definitely not one of that naive ...
391 views

### What is the area of my shapes?

I created overlapping geometries and I would like to know the area of the intersection. import geopandas as gpd from shapely.geometry import Polygon polys1 = gpd.GeoSeries([Polygon([(0,0), (0,1), (1,...
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### 90 angle between coordinate breaks when applied to world

I have a point A and direction DIR and a distant DIST Let's use A: `longitude: 139.33435143, latitude: 35.5385006, altitude: 0` DIR : `longitude: 139.33547146, latitude: 35.54034106, altitude: 0` ...
• 123
792 views

### QGIS Buffer distance vs Distance in Distance Matrix

I created Buffer (with Vector, Geoprocessing Tools) with 500 M distance from a point in the map (let's say Point A). I made another point (Point B) and it is not inside the 500 m Buffer. The Distance ...
3k views

### Cartesian coordinate convert to WGS84?

I am lost by various coordinate systems. This problem may be simple for you, but I still have no idea. A point P which WGS84 coordinate is (a, b, c). a, b, c represents longitude, latitude, altitude, ...
• 21
289 views

### QGIS Advanced digitizing switch from Cartesian to Ellipse

I´m trying to draw a line per length, but I need to enter the length in the Ellipse value. Is there a way to switch the values in the length window in the advanced digitizing panel from Cartesian to ...
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### How to use Leaflet with Proj4.js when GeoServer is serving tiles in EPSG:404000?

I have a GeoTIFF served via a GeoServer WMS service and referenced in the EPSG:404000 CRS (Wildcard 2D cartesian plane in metric unit). I would like to display the tiles in my Leaflet client and keep ...
1k views

### Non-Earth System in QGIS?

What I need is a function for Non Earth Coordinates in QGIS (both projects and layers). They should be mappable to any projected coordinate system (like SWEREF99TM). Why: In the Mining industry we ...
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180 views

### Which architecture to adopt when working with tile layers and Cartesian coordinates?

I'm currently working on a webmapping application dedicated to warehouse management. Where data is based on indoor geolocation and Cartesian coordinates system. More precisely, the map background is ...
3k views

### Treating latitude/longitude as a pair of polar coordinates

I have latitude longitude coordinates covering the whole globe that I wish to perform arithmetic operations (mean, interpolation) on without concern for ambiguous points and wrap around and without ...
1 vote
2k views

### QGIS Identify feature Cartesian area in degrees

In QGIS 3, the identify feature tool automatically calculates area. However, there are two areas: Cartesian and ellipsoid. The first is being calculated in degrees (not wanted) and the second in ...
1 vote
234 views

### Projecting latitude/longitude coordinates to Cartesian?

Let's say I have a square whose vertices are defined by coordinates in latitude/longitude format. I want to represent this square (and which ever shapes it contains, also defined as latitude/longitude)...
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1 vote