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1500 questions
35
votes
5 answers
Comparing different open source GIS servers?
I currently know the following open source GIS servers:
Geoserver: java based, vector and bitmap support, also supports. Is now on par with mapserver (performance-wise).
mapserver: c/c++, used to be the fastest server. Better for raster than…
nathanvda
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35
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3 answers
Finding centroid of cluster of points using R
While searching the web, solutions for finding centroids of polygons come up rather often. What I'm interested in is finding a centroid of a cluster of points. A weighted mean of sorts.
Can you provide some pointers, pseudo code (or even better, an…
Roman Luštrik
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35
votes
3 answers
Learning to think spatially rather than just follow point and click tutorials
The college I work for is considering revamping their intro to GIS course. Traditionally, they've used the ESRI suite but are now open to using other options. There are two factors responsible for the desire to make a change:
The text book provided…
NWT Adam
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35
votes
3 answers
Creating polygon grid using GeoPandas
I'm working with a GeoDataFrame of points and I need to create a grid of rectangular polygons.
I know how to have bounds of the GeoDataFrame with gdf.geometry.bounds. Now using this information and with two variables length and width (L, W) of…
Tim C.
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35
votes
2 answers
Was QgsMapLayerRegistry being removed in QGIS 3?
Is QgsMapLayerRegistry going to be availabe in PyQGIS with QGIS 3?
When I typed it into the QGIS python console (2.99), python seems to recognize it because it auto-completes qgis.core.QgsMapLayerRegistry, but then gives an error that it's not…
tinlyx
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35
votes
7 answers
Statistical tests for spatial line patterns?
There are plenty of tests for spatial point patterns that can be used to determine if points are distributed randomly or not, but are there any established tests for spatial line patterns? (I'm thinking straight lines, with just start and end point…
underdark
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35
votes
12 answers
Bulk geocoding 20 million US addresses
Are there any free or reasonably priced databases for the US which can be searched and return latitude and longitude information?
Chris Muench
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35
votes
10 answers
Shifting all features in vector dataset using Bash/OGR
Let's say that I put together a Shapefile and all the features have their vertices shifted by a constant amount.
What's the easiest way of shifting all the features (hence the (x,y) position of their vertices) by an arbitrary shift?
I have lots of…
Jose
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35
votes
9 answers
Adding GPX files into ArcMap?
What is the smoothest route, the easiest user experience, to add gpx files to ArcMap?
Ideally, I'd like to interact with .gpx with the same facility as .shp, being able drag'n'drop onto the map canvas and so on. Ultimately the results will be…
matt wilkie
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35
votes
3 answers
Why are Data Projections relevant?
Why is it useful to store data in unusual projections and datums?
I understand the value of projections as output constructs, because of distortion, etc: that much is justifiable.
However, I don't understand why, for instance, states use state…
tmcw
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35
votes
6 answers
Is there GIS Video "that Mom can understand"?
Working as a professional within the GIS discipline, I often find it challenging to describe to people what GIS is (in a face to face conversation). Telling them that GIS stands for Geographic Information Systems, which encompasses a set of…
artwork21
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35
votes
3 answers
Refering to another layer with Field Calculator in QGIS
Is there a way to select an attribute from a polygon layer and insert the value into a Virtual field of a point layer using "within" in the Field Calculator?
CASE
WHEN within($geometry, geometry_polygon) THEN attribute_polygon
END
Lunar Sea
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35
votes
5 answers
PostGIS nearest points with ST_Distance, kNN
I need to obtain on each element on one table the closest point of another table. The first table contains traffic signs and the second one the Entrance Halls of the town.
The thing is that I can't use ST_ClosestPoint function and I have to use…
Egidi
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35
votes
4 answers
More Efficient Spatial join in Python without QGIS, ArcGIS, PostGIS, etc
I'm attempting to do a spatial join much like the example here: Is there a python option to "join attributes by location"?. However, that approach seems really inefficient / slow. Even running this with a modest 250 points takes almost 2 minutes and…
jburrfischer
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34
votes
6 answers
PostGIS Geometry type not matching column type in QGIS
I'm trying to import some polygon shapefiles to Postgis in QGIS via SPIT. One of them can't be imported and returns this error:
ERROR: Geometry type (Polygon) does not match column type (MultiPolygon)
I've tried to change attribute "Feature Class"…
dmh126
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