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1500 questions
91
votes
5 answers
Getting polygon boundaries of City in JSON from Google Maps API?
When searching Google Maps for a city, the city's administrative boundary is displayed.
Is there a way to get the polygon boundaries of City in a JSON format using google maps api?
Luis Tiago
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88
votes
13 answers
Creating point features with exact coordinates in QGIS
How do I create point features with exact (manually entered) coordinates in QGIS?
I get precise GPS coordinates from a survey team which I need to add to a point layer. What I want: add point, type in the coordinates and when pressing enter the…
Per Engstrom
- 889
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- 6
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87
votes
8 answers
Managing large amounts of geospatial data?
How do you manage your geospatial data? I have terabytes of data spread out over hundreds of datasets, and have an ad-hoc solution using symbolic links within projects which link back to an domain-name based archive directory for each dataset. This…
scw
- 16,391
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87
votes
2 answers
Difference between WMTS and WMS
What is the main difference between a Web Map Tile Service (WMTS) and a Web Map Service (WMS)?
When should you choose one over the other?
What are the (dis)advantages by choosing one over the other?
I have read the Wikipedia entries.
Edward van Raak
- 1,047
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87
votes
6 answers
Visualising WKT geometry string in QGIS
Is there a simple tool in QGIS to graphically visualise geometry formatted as text?
Example geometry:
POLYGON((571178 6337246,571178 6402217,598061 6402217,598061 6337246,571178 6337246))
Result:
A layer in QGIS showing the polygon from above.
The…
Chau
- 4,480
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85
votes
5 answers
Getting started with PostGIS?
I have been reading a lot about PostGIS, but I am struggling to find a good beginner's guide.
Which tutorials/books do you recommend?
relima
- 2,810
- 4
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- 37
85
votes
2 answers
Calculating longitude length in miles
Suppose I have the geographic coordinates of "Saratoga, California, USA" as
Latitude: 37°15.8298′ N
Longitude: 122° 1.3806′ W
I know from here that in the case of latitude 1° ≈ 69 miles and that longitude varies:
1° longitude = cosine…
ABC
- 961
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- 7
- 7
84
votes
5 answers
Displaying coordinates and inputs as LatLon or LonLat?
I'm trying to get a sense if this is an issue for others or every input/output should be labeled so user is not confused and just go with it?
I think almost everyone pronounces it as "LatLon".
Who started it?
Is it because it's in alphabetical…
Vadim
- 3,971
- 2
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83
votes
31 answers
How to Start Web Mapping?
I want to start working on a web map at work to map some of our statistics by city.
I have an idea, but I'm not exactly sure where to start.
Are there any definitive resources that provide step by step guidance on how to do this?
Brian L
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81
votes
15 answers
Running Create Extension postgis gives ERROR could not open extension control file?
I have installed PostgreSQL 9.x and PostGIS 1.5/2.0 several times and have never had this problem.
I just got a new CentOS 6.3 server up and running and and I have Postgres 9.3 functioning as expected. I have run
yum install postgis2_93
and I can…
losthorse
- 913
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- 6
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79
votes
3 answers
Converting Pandas DataFrame to GeoDataFrame
This seems like a simple enough question, but I can't figure out how to convert a Pandas DataFrame to a GeoDataFrame for a spatial join?
Here is an example of what my data looks like using df.head():
Date/Time Lat Lon ID
0 …
atkat12
- 1,549
- 2
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78
votes
12 answers
Alternatives to using ArcPy
I seem to use ESRI's ArcPy site package for virtually all of my Python geoprocessing. To ESRI's credit, these are an incredible suite of tools that can help accomplish a great deal. However, I would also like to create geoprocessing scripts outside…
Aaron
- 51,658
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77
votes
12 answers
How much math does a GIS Analyst need to know?
For someone studying to pursue a career as a GIS Analyst, what math courses should he/she take?
Here's a long list of free Math courses from MIT to serve as a frame of reference.
Which are essential, useful, useless?
Kirk Kuykendall
- 25,787
- 8
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- 153
77
votes
2 answers
How accurate is approximating Earth as sphere?
What level of error do I encounter when approximating the earth as a sphere? Specifically, when dealing with the location of points and, for example, the great circle distances between them.
Are there any studies on the average and worst case error…
Jeff B
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77
votes
7 answers
Creating regular polygon grid in PostGIS
How to create, on the shape of a polygon, a regular grid of polygons/squares of an given size, in PostGIS?
I have thought about a function like Creating regular point grid inside polygon in PostGIS only for squares, so that squares can be 5m x 5m or…
mk.archaeo
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