36 votes
Accepted

Understanding difference between Coordinate System and Projection?

Both examples are coordinate systems. The difference is that WGS 84 is a geographic coordinate system, and UTM is a projected coordinate system. Geographic coordinate systems are based on a spheroid ...
Jyler's user avatar
  • 1,165
35 votes
Accepted

Re-project raster in python using GDAL?

So, thanks to @Luke I used the simple line: gdal.Warp(output_raster,input_raster,dstSRS='EPSG:4326') and it works, this was exactly what I was looking for, simple code with few line to execute simple ...
user88484's user avatar
  • 1,749
34 votes
Accepted

Is re-projection needed from SRID 4326 (WGS 84) to SRID 4269 (NAD 83)?

Well, technically, NAD83 is not a subset of WGS84. If you mine further in the SpatialReference.org projetion definitions, you can see the difference between the two projections. PROJ.4 definiton of ...
Gabor Farkas's user avatar
  • 4,578
33 votes
Accepted

Choosing coordinate system for mapping Mars in ArcGIS Desktop?

This is an intrinsic feature of ArcGIS. Just open "Geographic Coordinate Systems" folder, then the "Solar System" folder, then choose "Mars" and the datum associated with your data.
Vince's user avatar
  • 19.9k
32 votes

Unable to snap vertices and segment in QGIS 3.0

In QGIS 3.0, the snapping settings are accessed through the snapping toolbar. This is a change from previous versions. In QGIS 2.x they were accessed through Options menu > Snapping Options... ...
csk's user avatar
  • 24.5k
30 votes

Transforming Shapely Polygon and MultiPolygon objects

If you're using pyproj2, it's much easier to use a Transformer. Here's an example: import pyproj from shapely.ops import transform project = pyproj.Transformer.from_proj( pyproj.Proj(init='epsg:...
Nick ODell's user avatar
26 votes
Accepted

Extracting EPSG from a raster using gdal bindings in Python

I found the following workaround. I am unsure if it is the most efficient, but it does work for me. from osgeo import gdal, osr path = r"C:\temp\test2.tif" d = gdal.Open(path) proj = osr....
Lennert De Feyter's user avatar
25 votes
Accepted

Understanding reprojection?

Reprojection in GIS consists in changing the coordinates values of a dataset from one coordinate system to another coordinate system. Let's take a one dimensionnal case as an exampple. Imagine that ...
radouxju's user avatar
  • 49.4k
25 votes
Accepted

Changing shapefiles from geographic (WGS84) to projected (EPSG:2263) coordinate system using QGIS

This answer has four sections: What you should do to solve the problem and what you should avoid An example to better illustrate why assigning CRS and reprojecting are not the same An analogy that ...
Babel's user avatar
  • 67.2k
22 votes

How can EPSG:3857 be in meters?

It is a projection of a spheroid on a flat surface. Every projection has strengths and weaknesses and will preserve some elements of direction, distance or area better or worse than others (which is ...
MappaGnosis's user avatar
  • 33.7k
20 votes
Accepted

Showing the bounding box for every coordinate system in QGIS

Yes, QGIS holds this information in an SQLite table. Go the menu layer / data source manager and select Browser then go to where QGIS is installed (like C:\Program Files\QGIS 3.16\) and dig down to ...
JGH's user avatar
  • 40.8k
20 votes
Accepted

Calculating area of lat/lon polygons without transformation using GeoPandas

Overview Since version 0.7.0 geopandas has embedded the pyproj library as the crs object. pyproj, since version 2.3.0, has the ability to calculate the area of arbitrary polygons on a sphere. (see ...
Shawn's user avatar
  • 1,650
19 votes

Converting projected coordinates to lat/lon using Python

When using pyproj, note the differences from various releases in how it is used to transform data. Here are a few examples using new/old capabilities based on the question: Using pyproj >= 2.2.0 ...
Mike T's user avatar
  • 41.8k
19 votes
Accepted

Difference between datum and ellipsoid for geodetic coordinates?

No, a datum and ellipsoid are not equivalent. For a loose definition, think of the ellipsoid as defining size and shape. The datum then fixes that ellipsoid to the earth. NAD83 (various realizations) ...
mkennedy's user avatar
  • 18.8k
19 votes
Accepted

Does transforming to a new projection, then back, affect data accuracy?

I don't know which projection engine ArcGis uses, but a very interesting question also for proj.4. So I give it a try to test the proj.4 projection engine within the GNU-R environment. I use the NAD ...
huckfinn's user avatar
  • 3,518
19 votes
Accepted

Auto-select suitable UTM Zone based on Grid Intersection

There's the utm package, a bidirectional UTM-WGS84 converter for python. It's able to convert a (latitude, longitude) tuple into an UTM coordinate: import utm utm.from_latlon(51.2, 7.5) >>> (...
Antonio Falciano's user avatar
19 votes

What does "¢" mean in a coordinate?

Your viewer, or the website, has some problem with the fonts. Perhaps your browser does not get access to the defined fonts. Works for me, though, and this is how it should look: Coordinates are ...
user30184's user avatar
  • 63.1k
19 votes

Understanding Coordinate Reference System of QGIS Project and Layer

Short answer: there is project CRS and layer CRS: You can more or less freely choose any project CRS, QGIS handles the rest automatically. You can't "set" another CRS for your layer (your ...
Babel's user avatar
  • 67.2k
18 votes

EPSG 3857 or 4326 for Web Mapping

It's confusing when an API says it uses SRID 3857 but gives a location using SRID 4326 Quick way of telling what SRID your lat/lon is in: Look at how big the number & the precision EPSG:4326 is ...
user179876's user avatar
18 votes
Accepted

EPSG code for UTM zone

The UTM zones and their respective EPSG codes cover the whole area of their respecive zone from the equator to 84N / 80S. These areas are subdivided by the letters from South to North, and these again ...
user6072577's user avatar
  • 1,552
18 votes

Opening PRJ file in text editor?

Right click and open with a text editor like notepad (or Notepad ++). It's not a GIS layer, just some projection metadata on your layer. A shapefile is made of severall files with some mandatory. The ...
gisnside's user avatar
  • 7,798
17 votes
Accepted

Transforming single QgsGeometry object from one CRS to another using PyQGIS

Use QgsGeometry.transform(QgsCoordinateTransform). For example after created your instance of QgsCoordinateTransform with source and dest crs, for each geometry instance do: sourceCrs = ...
Luigi Pirelli's user avatar
17 votes

Create spatial polygon grid from spatial points in R

here is a solution using sf and sf::st_make_grid: library(raster) library(sf) e <- as(raster::extent(-125, -65, 25, 49), "SpatialPolygons") %>% st_as_sf() grd_lrg <- st_make_grid(e, ...
sebdalgarno's user avatar
  • 1,703
17 votes

Why do zones differ for WGS84 UTM in Google Earth Pro vs. in QGIS 3.4?

There are 60 UTM Zones, each 6 degrees wide (about 700km at the equator), and stretching from 84 degrees North to 80 degrees South (the poles are reference with the Universal Polar Stereographic grid ...
Christiaan Adams's user avatar
17 votes
Accepted

What kind of coordinates are 38,40.1365N, 75,4.23933W?

Mobile devices use WGS84 coordinates, and the coordinates might be displayed in different formats. One of them is DDM format. A comma for separating degree and minute, a dot for decimal. Your ...
Kadir Şahbaz's user avatar
16 votes

Difference between CRS (Coordinate Reference System) and SRS (Spatial Reference System)

As of Wikipedia: A spatial reference system (SRS) or coordinate reference system (CRS) They are synonyms. What you see in the linked article is the difference between the reference-ellipsoid ...
MakePeaceGreatAgain's user avatar
16 votes
Accepted

ST_DWithin Calc Meters - transform or cast?

As described, the answer is "neither", for the following reasons: Take a spatial table in 4326. Build a spatial index on it. The spatial index is a planar index, consisting of the 2D bounds of the ...
Paul Ramsey's user avatar
  • 19.8k
16 votes
Accepted

Creating custom Coordinate System in PostGIS

It's easy here Look it up on http://www.spatialreference.org Find it SR-ORG:7069 NAD_1983_HARN_StatePlane_Michigan_South_FIPS_2113_IntlFeet Click PostGIS spatial_ref_sys INSERT statement Run that ...
Evan Carroll's user avatar
  • 7,031
16 votes
Accepted

Adding Properties to a feature in Google Earth Engine

Yes, you can use the feature.set()option which Feature Overview covers with these examples: // Make a feature and set some properties. var feature = ee.Feature(ee.Geometry.Point([-122.22599, 37.17605]...
whyzar's user avatar
  • 12k
16 votes
Accepted

Reprojecting layer using PyQGIS

You can use processing algorithm native:reprojectlayer. Example: lyr = iface.activeLayer() parameter = { 'INPUT': lyr, 'TARGET_CRS': 'EPSG:4326', 'OUTPUT': 'memory:Reprojected' } result = ...
Fran Raga's user avatar
  • 7,808

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