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1500 questions
45
votes
9 answers
Downloading OpenStreetMap Data
Is there a straightforward way to download data from OpenStreetMap (OSM)?
Using North America as an example, I realize Cloudmade (Cloudmade no longer provides downloads of OSM) and Geofabrik (http://download.geofabrik.de/osm/north-america/) both…
djq
- 16,297
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- 182
45
votes
6 answers
Trilateration using 3 latitude/longitude points, and 3 distances?
I want to find out an unknown target location (latitude and longitude co-ordinates). There are 3 known points (latitude and longitude co-ordinate pairs) and for each point a distance in kilometers to the target location. How can I calculate the…
nohat
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45
votes
4 answers
How to insert a GeoJSON polygon into a PostGIS table?
I need to insert a polygon from GeoJSON to my PostGIS table. This is how the SQL query looks like.
INSERT INTO tablename (name, polygon)
VALUES (
'Name',
ST_GeomFromGeoJSON(
'{
"type": "Polygon",
…
danijar
- 1,184
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45
votes
2 answers
What is the difference between EPSG:900913 and EPSG:3857?
I'm using the QGIS google layers plugin to digitize a parcel as a shapefile. Later I want to import it to PostGIS. I know that google maps use a special 'google mercator' projection. What is the correct code of this projection: 900913 or 3857? Or…
Jiri Kadlec
- 451
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- 3
45
votes
9 answers
GRASS not working with QGIS says This algorithm cannot be run
I updated QGIS to version 3.6 using OSGEO4w
When I try to run any GRASS script, I get the following error message :
This algorithm cannot be run :-( The specified GRASS 7 folder
"C:\OSGEO4~1\bin\bin" does not contain a valid set of GRASS 7…
Kantan
- 1,917
- 2
- 14
- 26
45
votes
2 answers
Setting print layout to portrait using QGIS 3?
I can't get the print layout to appear in portrait. It opens in landscape and Layout/Page Setup... allows for portrait, but the layout canvas remains in landscape.
In 2.18 the "Composition" Panel has "Page Size" as its first item, with a drop down…
David
- 453
- 1
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- 5
45
votes
4 answers
Deciding what interpolation method to use for resampling raster data?
Are there hard and fast rules about which interpolation methods are suited to each kind of raster data?
ninesided
- 605
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45
votes
3 answers
What is the current Web Mercator projection code?
The web mercator projection, popularised by Google Maps, seems to be given a new EPSG code every couple of years.
EPSG:900913 (Google in calculator text) was an unofficial code
EPSG:3785 - is the projection I currently use for my datasets
However…
geographika
- 14,320
- 4
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- 77
44
votes
12 answers
Seeking top tier conference in GIScience?
In many fields, such as computer sciences, it seems to be quite clear which conferences are top tier and how a paper accepted to those conferences compares to journal publications in the same field.
Is there a general agreement in GIScience about…
underdark
- 84,148
- 21
- 231
- 413
44
votes
16 answers
Interview questions for hiring GIS Analyst?
What are some suitable interview questions to ask candidates for a GIS Analyst position?
I am looking for techniques for interviewing analysts at varied experience levels (we are currently looking at hiring for entry and senior-level positions). …
Britt Wescott
- 3,476
- 5
- 40
- 59
44
votes
7 answers
Comparing two spatial point patterns?
If I have two point pattern distributions within the same geographic region, how would I go about visually and quantitatively comparing those two distributions?
Also assume I have many points within a smaller region, so simply displaying a pin map…
Andy W
- 4,234
- 5
- 45
- 69
44
votes
10 answers
Seeking spatial R tricks
R is becoming pretty strong tool for handling and analyzing spatial data. I learned some useful things through questions like these at SO and thought it might be useful to have something simmilar, but more 'spatially' oriented.
Can you share some…
radek
- 10,579
- 12
- 86
- 121
44
votes
3 answers
Ignoring invalid input features with Intersection tool in QGIS?
In QGIS 2.18, when I used the Vector > Geoprocessing Tools > Intersection tool, I was able to check an option which said "Ignore NULL geometries [optional]".
Now I've downloaded QGIS 3.2 and that option no longer exists. But when I try to create the…
Felipe D.
- 2,509
- 2
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44
votes
2 answers
R convert sf object back to SpatialPolygonsDataFrame
How do I convert an sf object back to a SpatialPolygonsDataFrame?
I am running R 3.4.0 and sf version 0.4.1. The sf documentation mentions an as_Spatial function, but this isn't available in my install (for some reason).
Simon
- 835
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44
votes
5 answers
Calculating average width of polygon?
I'm interested in examining the average width of a polygon that represents the road surface. I also have the road centerline as a vector (which is sometimes not exactly in the center). In this example, the road-centerline is in red, and the polygon…
djq
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- 182