GIS Stack Exchange
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1500 questions
27
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1 answer

Accessing QGIS plugins in Python?

Is there a way to access QGIS plugins in Python? I'd like to write a script to do some geoprocessing, and I'd like to use the clip, regular points and convex hull tools in fTools, as well as the Road graph plugin. The latter is probably a different…
mattwigway
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6 answers

Creating a small web-mapping/map-tiling service

I am looking for a small-scale and easy way to present one or more polygon shapefiles online (on a municipal website without any existing map-server infrastructure, to be precise). Right now, I'm doing all work with QGIS, and I would prefer to stay…
SAnderka
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26
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5 answers

Obtaining print quality PDF or PNG output from QGIS?

I work with people who use ArcGIS Desktop and they have found the best resolution output images are made by creating PDFs. They tell me that *.png and the rest out of ArcGIS Desktop are not satisfactory and that they do not bother with them.…
BWill
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26
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9 answers

Getting started with ArcObjects?

What is the best route or place to get started with ArcObjects if one is not a developer and not aiming to become a developer? I've been using gis professionally for a long time, almost two decades, arcinfo/arcgis for most of that; I'm pretty good.…
matt wilkie
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26
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4 answers

Making map where overlapping symbols increase Opacity?

I was looking at some maps like: Map from Ship Logs or the Facebook worldwide friendships Mapped (via the Flowing Data blog) These Maps look good because single lines are almost transparent, and as more and more lines are drawn, the opacity goes…
Devdatta Tengshe
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26
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5 answers

Adding attribute field to existing Shapefile via Python without ArcGIS

I have a Python script that adds an attribute field to a Shapefile if doesn't exist. This is easy to do with ArcGIS (graphically or via Python), but I'm looking for something that doesn't depend on ArcGIS. I tried this unsuccessfully with OGR, since…
Mike T
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26
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3 answers

Displaying world country shapefiles centered on Pacific Ocean using Robinson or Miller Cylindrical projection in QGIS?

I wish to display a map in QGIS (world country shapefiles) showing all countries but centered on the Pacific area. I am not familiar with Proj4, so is there any way this can be done in QGIS?
user21658
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26
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5 answers

What makes a MXD file size larger and how to decrease its size?

I know that MXD contains information about layers, symbology and configuration of default tools. I have a few that are exceeding 50 MB and are starting to take a while to load up. What are some of the main things that will increase a MXD's file…
Cody Brown
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26
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7 answers

Creating points in specified distance along line using QGIS

I want to use QGIS creating points along the line, but in specified distance. I found two GRASS tools in SEXTANTE Toolbox： v.to.points v.segment I tried v.to.points, setting the maximum distance between points in map units to 100 and got…
Heinz
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26
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1 answer

What does the adoption of Python by NVIDIA for GPGPU mean for GIS?

Today NVIDIA announced support for the Python language on its flavor of GPGPU (CUDA). Manifold GIS uses CUDA to enable some accelerated raster operations but it is not a programmable environment and is limited to what functions its developer has…
blah238
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26
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1 answer

Change marker icon on click using leaflet

I have a map with many (>100) markers on it. I would like to make it so that clicking on these changes the icon to a highlighted version. I've created two custom icons, one regular, and one highlighted. I've gotten this to work with single…
DaleSwanson
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26
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3 answers

Differences between Raster Dataset, Raster Catalog, and Raster Mosaic

I have about 40 scanned, colorful Geology maps that are GeoTiffs. I want to bring them into an Esri FileGeodatabase to lower their size, combine them as one and display them with a mostly transparent overlay that is also scanned. Right now they…
cndnflyr
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26
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2 answers

Creating Thiessen (Voronoi) polygons using lines (rather than points) as the input features?

I have a set of line features inside a particular polygonal boundary. For each line, I'd like to generate a polygon inside which every possible point is closer to the given line than to any other line in the layer. I've done this in the past for…
Dan C
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26
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4 answers

Is there any online tool for converting coordinates between different EPSG?

Every time I want to do conversion, I need to get into the console to run proj.4. Is there any online tools for converting coordinates between different EPSG?
Harold Chan
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26
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1 answer

Merging adjacent polygons in shapefile that has been split at tile boundaries?

I'm currently using building data from the Ordnance Survey Vectormap District and I've noticed that a lot of building polygons are split in 2 because of the way the OS split up the shapefile. This is what I'm seeing in QGIS – I've highlighted some…
Robin Hawkes
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