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1500 questions
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3 answers

Adding shapefiles to PostGIS database

I was able to create a Postgresql database and then I executed, createlang plpgsql geospecies psql -d geospecies -f postgis.sql psql -d geospecies -f spatial_ref_sys.sql So now can I directly import the shapefiles? Would this be the right…
Sam007
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47
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3 answers

Reprojecting all geometries in PostGIS table?

I created a spatial table with SRID:4326. Now I want to change total projection to SRID:32644 into a new table. The old table should remain unchanged.
Satya Chandra
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47
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1 answer

What is the default plugin folder location in QGIS 3?

I am searching for default location for QGIS 3 Plugin folder I checked here but could not find: C:\Program Files\QGIS 3.0\apps\qgis\python\plugins C:\Users\Abhijit\.qgis2 (cannot locate .qgis3, should it be there ?)
Abhijit Gujar
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47
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5 answers

Splitting shapefile into separate files for each feature using QGIS or SAGA

I have a polyline shapefile with about 20 kinds of roads. I would like to know how can I create automatically a vector file for each one. I am aware of how to do it using ArcGIS Desktop - see Exporting feature class into multiple feature classes…
Bobo
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47
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3 answers

Manually placing labels in QGIS?

Is there a way to manually place labels in QGIS? I have a map which has almost-duplicate labels in some places (e.g. E 1st St and 1st St) and I'd like to remove some of them. Also, I'd like to move some of the labels around and maybe label some…
mattwigway
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47
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4 answers

Free GIS workshops, tutorials, and applied learning material

This Q&A lists free as in $0 workshops in GIS and related fields that have their material available to view or download online. The list is not limited to FOSS GIS, as GISers usually use a combination of open and closed source tools to accomplish…
dassouki
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47
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7 answers

Tuning PostGIS for production environments

What PostGIS documentation have you come across that has been helpful when tuning PostGIS for a production environment? I would like to get together with my DBA to setup a Postgresql/PostGIS installation that is fit for production. I have read that…
Ando
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46
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12 answers

Map matching links and ideas?

I'm using OpenStreetMap and its vectorial road network and I'd like to implement a map matcher algorithm. Currently I'm able, for each GPS position, to retrieve the nearest road segment and calculate the projection of this position to that segment,…
yonel
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46
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1 answer

Getting pixel value of GDAL raster under OGR point without NumPy?

I am working on a computational model of the abundance of wild pollinators across a landscape. The model itself is complete, and I am now struggling with a post-processing step. I have my GDAL pollinator supply raster that looks something like this…
James
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46
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10 answers

Determining the centroid of polygons in QGIS

I have a polygon vector and I want to quickly attain the centroid of this polygon for insertion in a text document. I am working with QGIS. I searched through other questions and although some are somewhat close they don't quite answer my…
David
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46
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1 answer

Installing QGIS plugin when offline

Due to various IT policies at my workplace, QGIS is installed on a machine that is not connected to the Internet. I wish to install a couple of QGIS plugins on this system. I have downloaded the required plugins from…
Devdatta Tengshe
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46
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3 answers

How can I convert data in the form of lat, lon, value into a raster file using R?

I have a data set of values over a km grid in the continental U.S. The columns are "latitude", "longitude", and "observation", e.g.: "lat" "lon" "yield" 25.567 -120.347 3.6 25.832 -120.400 2.6 26.097 -120.454 3.4 26.363 -120.508 …
Abe
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46
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6 answers

Using geohash for proximity searches

I'm looking to optimize point proximity geo searches time. My input is lat,lng point and I'm searching on a precomputed set of locations to n nearest points. I don't care how much time/space the building of the precomputed index of locations will…
Maxim Veksler
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46
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3 answers

Are there newer routing algorithms (than Dijkstra, A*) in GIS databases?

There are works like Reach for A* from Microsoft researchers and Highway Hierarchies by Sanders and Schtolz (if I spell the name correctly) from Karlsruhe Uni. Both of them reduce the calculations order a lot, and speed up thousand times on large…
culebrón
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45
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3 answers

Performing bounding box query in PostGIS?

I have a PostgreSQL table, with almost 2 million rows, with a long-lat coordinates field in the form POINT(-73.4938 33.2405). Supposing there's a geospatial index on that field, what's the most efficient, fastest way to select all the rows within…
Avishai
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