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1500 questions
57
votes
3 answers
How can I get a shapefile from a postgis query?
My data is in a PostGIS database. I would like to generate a shapefile from a query. How can I do that?
rudivonstaden
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57
votes
6 answers
How to call gdal_translate from Python code?
Is it possible to use some gdal API to call gdal_translate from Python code? I do not mean simply executing the gdal_translate.exe from the file system, but rather call it somehow in code so I do not need to know the exact directory the…
Katie E.
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57
votes
5 answers
Which character encoding is used by the DBF file in shapefiles?
Which character-encoding is used by the dbf-file in shapefiles? It seems it is handled different, based on the program and the local encoding-settings of the machine. Which encoding is 'right' - specified for the format?
Mnementh
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57
votes
6 answers
Is there an automatic function in QGIS to package all files in a project for transferability?
In my project, I use a lot of geodata from different directories.
Now I want to give the QGIS project to a colleague (eg on a CD).
Is it possible to copy the shapes from different directories automatically to one directory?
Hendrik Pehlke
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57
votes
10 answers
Missing Processing Tools in Vector Menu of QGIS
I'm missing all the usual processing tools in the Vector menu in QGIS 2.16 (e.g. Vector Overlay, Analysis, etc). They do appear in the processing toolbox but there's no sign of them in the Vector menu. Has anyone come across this issue?
user77875
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57
votes
8 answers
Сreating polygons with straight lines and right angles in QGIS
When creating a polygon, how do I do it so that the lines are straight (90, 0 degrees, etc.) and when I create corners they can be right angles?
For instance, how do I create a perfect square or rectangle?
hpy
- 3,157
- 13
- 43
- 43
57
votes
9 answers
Why does GPS positioning require four satellites?
I have a question on the GPS positioning algorithm. In all books I've read for 3D positioning we need four satellites, and I don't understand why.
We need to calculate three variables: x, y, z. We know when satellite send the signal to earth and…
matekm
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56
votes
10 answers
Selecting features that do NOT intersect in PostGIS
Using PostGIS, I just want to select points that fall outside of polygons. Ultimately this is the inverse of the ST_Intersects, as far as I can see it.
Example: I have a taxlot layer and a address point layer. I assume I should be using the…
RyanKDalton
- 23,068
- 17
- 110
- 178
56
votes
3 answers
Transforming Shapely Polygon and MultiPolygon objects
Is there an easy way of transforming Shapely objects (namely, Polygons and MultiPolygons) from one projection to another without having to dig around and extract coordinates by hand?
In fact, I don't even care if they are Shapely objects at this…
Chris Fonnesbeck
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56
votes
4 answers
Why has Web Mercator (auxiliary sphere) become the web map standard?
I understand what the difference is between the Web Mercator projection and Web Mercator Auxiliary Sphere (WMAS). I also understand that both Google and Esri have adopted this projection as their primary projection for their web-maps which is why we…
dkroy
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55
votes
14 answers
The GIS of War - Tracking Conflicts and Their Effects
I was idly speculating on the many sorts of things people are keeping track of these days with GIS - natural/human catastrophes, demographic and economic patterns, climate change, etc. In that vein, I started to look around for GIS' applications in…
Nathanus
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55
votes
3 answers
How to calculate polygon centroids in R (for non-contiguous shapes)
I've spent a little while figuring out the answer to this question.
It's not immediately obvious from a Google search, so thought it may useful to post the answer on here. There is also an additional question about non-contiguous polygons.
Instant…
RobinLovelace
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55
votes
7 answers
Converting KMZ-file to KML
Is there an easy way (like unzip) to convert a KMZ-file to KML?
Abe
- 1,933
- 3
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55
votes
9 answers
Creating drive time polygons using Open Source tools?
Is anyone using open source tools and/or data to generate drive time polygons that radiate out from a given location? For example, I have used ESRI products like Network Analyst and Business Analyst to generate polygon boundaries that represent the…
RyanKDalton
- 23,068
- 17
- 110
- 178
55
votes
6 answers
Will the OpenLayers Plugin be updated for QGIS3?
Upon searching for the OpenLayers plugin, it shows that this plugin is incompatible with version QGIS 3.0. Will this be updated? Is there another way to add Google imagery or any other aerial imagery other than through this plugin?
I noticed the…
TMAC_0819
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