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1500 questions
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3 answers

What does M-value represent?

I am trying to wrap my ahead around the meaning of the M-value. I read ESRI's dictionary definition here: https://support.esri.com/en/other-resources/gis-dictionary/term/m-value and was not able to get a good grasp of the concept. What does the…
NULL.Dude
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What algorithm should I use for wifi geolocation?

School Pickup Use Case (update) It might be helpful to go into a more concrete use case instead of the original backyard example below. Local law enforcement has started cracking down on use text messaging and cell phone use in school zones. This…
Kirk Kuykendall
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Setup QGIS with local plugin repository only

Is there a best practice how to setup QGIS without the official repository but only with a local repository? The idea behind this is to setup a stable environment where local GIS-admins check plugins before they are added to the local repository.…
Thomas B
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16
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7 answers

Find/Replace Double Quotes using Python Parser of ArcGIS Field Calculator?

I'm trying to use the Field Calculator (ArcMap 10.0) to strip out double quotes in an address field (I didn't put them in there, believe me). I've tried many incantations but am still unable to even get off the ground with a calculation. yes, both…
Random Geo guy
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3 answers

Cartographic techniques for symbolizing routing data

Some common problems with displaying routes created from street data, such as bus routes, include: Routes may overlap themselves, such as when a route takes the same road in opposite directions Routes may overlap other routes that take the same…
blah238
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16
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2 answers

How do you protect your PostGIS credentials when using QGIS 1.7?

I'm fairly certain this should be a community wiki, but I don't know how to make it one. So if an admin sees this please change if appropriate. So... how do you protect your PostGIS database data when using QGIS 1.7? (I am using QGIS 1.7 and PostGIS…
Ando
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1 answer

Seeking AutoTrace/Trace Tool in QGIS 3?

Have made the move to QGIS 3 but am having trouble locating the AutoTrace/Trace tool. I have enabled advanced digitizing tools where the magnet button sat in QGIS 2.18 but it is not there in QGIS 3. I also can't find any AutoTrace plugins in the…
Ben
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How does QGIS Zonal Statistics handle partially overlapping pixels?

There are a couple Stackexchange posts asking this question, but neither of them were sufficiently answered: How does Zonal Statistics work exactly? How does Zonal statistics handle pixels that are on the border of the polygon? I am writing Python…
Jon
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Merging Multiple Tables into New Table in PostGIS

I am looking to merge a number of individual tables into a new table in PostGIS. This is an easy task when working with Shapefile data, but I am unsure how to do this in PostGIS. I think I use Append, but I am unsure even where to start.
Ryan Garnett
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2 answers

Why are Galileo satellites inaccessible in USA?

I see that some (or all?) Android devices that support Galileo global positioning system are deliberately programmed to self-disable their Galileo support when used in USA or US territories. This applies to Sony Xperia XZ Premium, for one example,…
AnT stands with Russia
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2 answers

Clipping Error 1: Cutline polygon is invalid

I used the sample files located at this URL to learn QGIS: https://qgis.org/downloads/data/. I tried to clip SR_50M_alaska_nad.tif using a shapefile as a mask (alaska.shp). The problem is I got this error which states that: Ring…
bryan
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1 answer

Performing Network Analysis for Emergency Response using ArcGIS Desktop?

I am working on a project using Network Analyst to determine official emergency response zones for fire departments. The shape of each zone will be determined by the network (at least 1 department must arrive at the destination within 4 minutes of…
Tanner
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3 answers

Creating Spatial Index for GeoPackage using QGIS

Working in QGIS 2.18.14 standalone on Windows, is there a way to create a Spatial Index for GeoPackage (gpkg) layers?
Kazuhito
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2 answers

How to filter features in a layer?

I am trying to display certain features in a shapefile-based layer using QGIS. I have found the subset function in the properties panel, which does exactly what i want, but is too tedious given that I have to manually sift through a large number of…
dietmar
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5 answers

Changing feature class and field aliases in bulk using ArcPy?

I have over a hundred FCs, each with 10 or 20 attributes to add or change the aliases for, two or more times a year. Needless to say, this is not something I'm going to grunt my way through. How can I automate this process? Python solution preferred…
matt wilkie
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