Geographic Information Systems Stack Exchange Community Digest

Top new questions this week:

Removing/detecting polygons that are infinitely thin, and look like lines

I have a a dataframe of polygons in GeoPandas/shapely. Most of them are valid, and remaining invalid polygons can be removed with ".is_valid" command. However, some polygons are in theory ...

qgis python polygon line geopandas  
user avatar asked by Sjieke Score of 5
user avatar answered by GBG Score of 6

Is "order by" clause in DBSCAN necessary?

In the following code, is "order by" necessary for the DBScan function or is it adding an overhead for no reason? clustering as( SELECT row_id, city_id , imei, speed, points_geom ,...

postgis clustering  
user avatar asked by analyst92 Score of 4
user avatar answered by dbaston Score of 6

Why would the NHD have wrong information / how to correct it?

According to the National Hydrography Dataset, the Blanco River in Texas consists of 108.3km of "artificial paths", 36.677km of it is a perennial river and 2.297km of it is an intermittent ...

united-states nhd  
user avatar asked by neubert Score of 3
user avatar answered by Hornbydd Score of 1

Maximisation of circles that don't intersect other geometries within a given layer using QGIS

My context is an orchard in which certain trees already exist. I want to plant new trees that have to be at 10m from any other trees and from the border of the orchard. The grey points in the image ...

qgis tools circle  
user avatar asked by jo.H Score of 3
user avatar answered by Comrade Che Score of 2

How to mask everything but a polygon in QGIS?

I am able to draw polygons over areas of interest in QGIS. For example via: Layer -> Create Layer -> New Temporary Scratch Layer, name the layer, select Polygon as Geometry type, OK, select the ...

qgis polygon masking qgsmapcanvas mapcanvas  
user avatar asked by zabop Score of 3
user avatar answered by katagena Score of 5

Determine if a polygon can be translated to contain another

I would like to determine whether a polygon could or could not fit inside another polygon. This latter polygon can be translated arbitrarily. A Python example: from shapely.geometry import Polygon ...

python polygon geometry shapely translate  
user avatar asked by zabop Score of 3
user avatar answered by swiss_knight Score of 2

Deleting vertices inside polygon area in QGIS

I am trying to remove vertices inside a polygon area which do not form an outside boundary to the polygon. Example picture below with the vertices to be removed in red markings. Deleting the vertices ...

qgis polygon geometry vertices dangle  
user avatar asked by gishelp Score of 3
user avatar answered by Federica Gaspari Score of 4

Greatest hits from previous weeks:

Renaming attributes/fields in shapefile attribute table using QGIS

I would like to rename some fields in my attribute table: Like rename "XRF_N3"in something else. It seems quite a easy issue but I don't find any information about how can I do that.

qgis shapefile attribute-table fields-attributes rename  
user avatar asked by G M Score of 92
user avatar answered by underdark Score of 125

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 ...

postgresql postgis-2.0 centos  
user avatar asked by losthorse Score of 73
user avatar answered by Paul Ramsey Score of 15

Merging multiple vector layers to one layer using QGIS

I've imported several shapefiles which where exported from a Mapinfo .tab. Several .tab-files are imported resulting in 20+ layers. Afterwards I want to export it to GeoJSON; but I'm reluctant to ...

qgis shapefile merge  
user avatar asked by stUrb Score of 107
user avatar answered by Aragon Score of 90

Creating Centrelines from Road Polygons/Casings using ArcGIS Desktop?

I want to create center lines from road polygons. Are there any automated tools in ArcGIS for Desktop to do this? I am including a Screenshot of my vector file below.

arcgis-desktop road  
user avatar asked by Binoy Score of 31
user avatar answered by Binoy Score of 11

Fixing Runtime Error R6034: application has made attempt to load C runtime library incorrectly?

I just downloaded QGIS 2.0 and every time I open it I get this error message window popping up: Does anyone know what this means or how I might be able to fix it?

qgis installation qgis-2  
user avatar asked by CZuck Score of 8
user avatar answered by shawty Score of 8

Displaying only selected features on map in QGIS

Not sure if this option ever existed, but the new QGIS version hides a lot of things somewhere else and this seems so simple that I'm kind of convinced it was possible to do this before. I have quite ...

qgis features select display  
user avatar asked by Kristina Score of 41
user avatar answered by Dan C Score of 43

Panchromatic Image association with high spatial resolution

How and Why is a Panchromatic Satellite Image associated with high spatial resolution? I googled and found that it is a single band image, but then why is it called pan-chromatic(All Colors). Does it ...

remote-sensing imagery image digital-image-processing  
user avatar asked by Abhishek Potnis Score of 20
user avatar answered by WhiteboxDev Score of 38

Can you answer these questions?

Moving database from ArcGIS Online Feature Layer to Microsoft Access

I have a project that involves collecting data in Survey123 (hosted as a ArcGIS Online Feature Layer) and conducting QA/QC in Microsoft Access. We're trying to come up with the best process for moving ...

arcmap arcgis-pro ms-access arcgis-survey123  
user avatar asked by WindRiver Score of 1
user avatar answered by Hornbydd Score of 0

Calculating speed at points via window functions

I want to calculate speed at every point for each device_id, such that there is a new column of "speed" attached to the current dataset My dataset is like: imei(device_id) point_geom(...

postgis  
user avatar asked by analyst92 Score of 1

Looking for proper GIS terminology - polygon with a cut in it

(QGIS,GDAL/OGR) I have a polygon produced by contouring that has a small short overlapping line segment. I am wondering if there is a proper GIS term for this and whether there is an automated method ...

qgis gdal polygon ogr  
user avatar asked by Brendan Score of 1
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