6
votes
Accepted
Rotating a set of points with an angle with rotation matrix: why is result "distorted"
There is nothing wrong with the rotation. It is a side effect from visualization. If you look at the picture captured from QGIS, you will see that the dots do not only get bigger and smaller, but also ...
- 76.2k
4
votes
Artefacts in Sentinel 1 Imagery
This is RFI from (mostly) ground based radars and other EM sources. I've wrote about it here. You can't "clear" it up completely, but using lower DB values, or aggregating them over time, ...
- 8,566
4
votes
Accepted
Clipping vector layers with different CRS
Eliot has right. You might perform a projection instead of reprojection.
Your data were created in differents CRS, that's mean that coordinates of your geometries are not the same but with OFP (on ...
- 2,191
4
votes
Accepted
Distorted H3 hexagons - even though projection is matching
The definition of EPSG:4326 is simply just a representation of the WGS84 coordinate system which is a 1:1 mapping from the spheroid to an XY plane.
And, while WGS84 is the correct spheroid for h3 ...
- 3,741
3
votes
Accepted
ST_AsMVT vector tiles distort at low zoom levels
The tile_ul function computes lon/lat values (EPSG:4326), assuming that its inputs are tile coordinates in the Pseudo-Mercator projection (EPSG:3857).
The code then uses the lon/lat values to clip the ...
- 1,973
3
votes
Accepted
Fix distortions when reprojecting cshapes world maps?
You can use raster::crop to remove nodes that are just smaller than -180 or larger than 180
library(cshapes)
library(raster)
wmap <- cshp(date=as.Date("2012-06-30"))
w <- crop(wmap, extent(-...
- 10.4k
3
votes
Accepted
Distance in SRTM image vs. Google Earth/etc
Yes, this is most likely a projection issue.
Google/Bing imagery are presented at a Spatial Reference System known as Pseudo Mercator (also known as Web Mercator). This is a projected SRS based on ...
- 3,151
2
votes
Distorted image of KML in QGIS
I had this experience, and it stopped being a problem when I switched my Qgis projects over to use EPSG:3857 as the CRS.
KML files can only have by default one particular CRS which can't be changed. ...
- 307
2
votes
Resampling WGS84 to ETRS89 causes change in pixel dimension
The 30m is a rough estimation. The actual number of meters depends on the latitude. See https://gis.stackexchange.com/a/208739 for some numbers.
PS: For Europe the EPSG:3035 "ETRS-LAEA" is ...
- 10.8k
2
votes
True non-projected 3D grid world modeling
A high-precision, global 3D Cartesian coordinate system is quite useful to the aerospace industry, where satellites orbit the Earth at large enough distances that understanding the true geometry ...
- 1,474
2
votes
True non-projected 3D grid world modeling
It is true that data in a global 3D cartesian coordinate system will allow you to do distortion-free calculations of 3D distances and angles. And if users are happy with perspective views of the 3D ...
- 8,888
2
votes
Creating time-space map by distorting city-points polygons using QGIS?
To create a cartogram as in your first image you can use either Darcy software or DistanceCartogram Qgis plugin (there probably are other tools for distance cartograms - but if I'm not mistaken those ...
- 883
2
votes
Accepted
What is the area of my shapes?
All geometric operations that GeoPandas performs depends on Shapely package. Shapely performs all operations in the x-y plane. That means Shapely doesn't care if a shape is located at equator or at a ...
- 76.2k
2
votes
Accepted
Shift country polygons to other world-regions in QGIS, adapting it's size corresponding to the true area
A relative simple solution would involve these steps:
On the layer in Web Mercator projection (EPSG:3857), create a new attribute with field calculator, calclulating the area distortion of each ...
- 67.3k
1
vote
Accepted
Export distortion grid and displacement vectors from MapAnalyst and use them in QGIS: incorrect projection
The trick is to apply the distortion grid to the new map (the OpenStreetMap basemap on the right side). This map is georeferenced, unlike the (ungeoreferenced) old map image, basically a scanned ...
- 67.3k
1
vote
Distorted h3 hexagons using h3js with Mapbox
Something is definitely off there - while H3 hexagons do have some distortion in various parts of the globe, and while this distortion is further distorted at extreme latitudes when rendered in a ...
- 346
1
vote
Accepted
Leaflet activearea interferes with esri-lealet imagelayer
Problem stems from the fact that esri-leaflet image layer is calling Leaflet map getBounds() method, which is modified by leaflet-active-area plugin to return only active area bounds instead of map ...
- 24.1k
1
vote
How do I rectify a distorted aerial image in QGIS?
The image is being reprojected on-the-fly to the map Coordinate Reference System (CRS), which is not the same as the image CRS.
You can change the map CRS with the Project ~> Properties ~> CRS ...
- 14k
1
vote
Accepted
QGIS distorted contour from DEM
Oddly the MME GeoTIFF looks like a rhombus too in QGIS, but not in a
TIFF viewer.
Obviously the projection (CRS) of the TIFF file differs from the projection (CRS) of your QGIS map canvas. To ...
- 2,050
1
vote
Evaluating map projection scale error
We used a similar spreadsheet method developed by NGS for evaluating projection distortion statewide. We mapped the points and gave them a symbology classification that made it easy to visually ...
- 41
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