All Questions

33,120 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
32 votes
0 answers
3k views

Leaflet v1 plugin: layer control for ungrouped, grouped, and nested-grouped layers

I need a Leaflet plugin which extends L.Control.Layers. I have the following requirements: works with Leaflet 1.x handles ungrouped layers alongside grouped ones handles nested layer groups does not ...
user avatar
  • 5,582
17 votes
0 answers
825 views

Parsing file format for attributes in Raster Product Format (RPF) maps and imagery?

I'm trying to implement an open-source NITF reader (using only java, no external libraries such as GDAL or NITRO), and its mostly going OK. However I'm having trouble understanding the RPF extensions, ...
user avatar
  • 12.5k
16 votes
0 answers
2k views

Extract TopoJSON directly from PostGIS

I have a simple "region" table: id (TEXT), name (TEXT), geom (MULTIPOLYGON). Here's the query I can use to extract a GeoJSON FeatureCollection: SELECT row_to_json(fc) FROM ( SELECT '...
user avatar
  • 469
16 votes
0 answers
1k views

Constructing a Voronoi diagram using a complicated travel time metric

I have in my possession four sets of shapefiles: 1. Locations (points), around 1000 2. Roads (lines), each road has a speed attribute 3. Terrain (polygons), each zone also has a speed attribute 4. ...
user avatar
  • 281
14 votes
0 answers
646 views

High PostgreSQL/PostGIS memory and disk usage when saving QGIS project

Why would simply pressing the Save button in QGIS cause my local PostgreSQL instance to cause memory and disk usage to spike to "Not Responding" levels? Seems to me like the PostgreSQL ...
user avatar
  • 22.4k
13 votes
0 answers
552 views

Remove reference to raster layer object PyQGIS

I am developing a plugin to load a set of raster files on QGIS. When there is a large number of files to be loaded, the main UI freezes. So I use QgsTask to move the creation of raster layers to a ...
user avatar
  • 136
12 votes
0 answers
405 views

Accessing watershed boundary for lakes in R

I have had success accessing unique database IDs and polygons for various lakes in the US. I'm now looking to get polygons for the watersheds associated with these lakes, but have stumbled a bit. ...
user avatar
  • 205
12 votes
0 answers
2k views

Making polygon for every point in set using Voronoi diagram

I'm trying to make polygons from points, where each point will be represented by one polygon. I tried using Voronois, but the results are incomplete. While I more or less understand where this ...
user avatar
  • 569
12 votes
0 answers
278 views

Processing post-execution script hook to clear scratch layers?

I've been cobbling together some Processing scripts for QGIS 2.18 (I'm not a fan of QGIS 3 scripts), and I keep running into one particular problem: my script creates a lot of scratch layers and they ...
user avatar
  • 565
12 votes
0 answers
506 views

MapScript with Python 3

I am trying to build raster summarizing features into a GeoDjango webmap, and would like to use the django-raster and django-wms packages to do so. I believe that I have them set up correctly, but am ...
user avatar
  • 1,249
11 votes
0 answers
368 views

Multithreaded DB connection for QGIS plugin

I am using QGIS 2.18.21 and PostgreSQL 9.6. on a Windows 8 machine. I am trying to do processing of a certain database task in the background, and I want the user to be able to continue to work in ...
user avatar
11 votes
0 answers
299 views

ESRI Runtime Geodatabase Shape storage

Does anyone out there know the geometry storage encoding for ESRI's Runtime Geodatabase (.sqlite) format? aka mobile geodatabase. There are 'GDB_ tables', 'st_ tables', 'RTREE indexes' and other ...
user avatar
  • 1,990
10 votes
0 answers
251 views

Saving ArcGIS Pro symbology to PostGIS DB for each layer

I want to have a default style/symbology assigned to each layer in a PostGIS database so that whenever it is loaded in ArcGIS Pro, it will come up with the default style. There is a way in QGIS to ...
user avatar
  • 1,385
10 votes
0 answers
579 views

PyQgis Exporting Print Layout: "ERROR 6: The PNG driver does not support update access to existing datasets."

I am trying to export a .tif loaded into a pre-configured print layout template and further exported as .png def openLayer(project, fp, basename, vector=True): layer = QgsVectorLayer(fp, basename) ...
user avatar
10 votes
0 answers
387 views

PyQGIS script crashes QGIS 3 when removing a custom pluginLayer which has custom legend

I upgrade a 2.18 plugin to 3.4. PluginLayer has been refactored and I could not create a custom legend as simple as previous major version of QGIS 2 : QgsDefaultPluginLayerLegend was removed. Use ...
user avatar
10 votes
0 answers
473 views

Calculate volume of space defined by multiple overlapping 3D polygons

I have thousands of 3D polygons scattered in space but they mostly overlap with many of their neighbors in big extent. Is there any way how to compute volume they define effectively? I would love ...
user avatar
  • 203
10 votes
0 answers
323 views

Defining partial or complete overlap with QgsSpatialIndex

I'm working on adding some functionality to a QGIS plugin. It currently uses a QgsSpatialIndex to efficiently compute whether the features of a vector layer intersect (potentially millions) of ...
user avatar
10 votes
3 answers
917 views

Raster smoothing using ArcMap

I need to simulate a debris avalanche, but in my elevation raster the avalanche deposit is included so I'd need to take it off to simulate on a pre-avalanche-like surface. Unfortunately the only data ...
user avatar
10 votes
0 answers
1k views

What is the convergence threshold for ArcGIS Iso Cluster?

The ArcGIS tool Iso Cluster Unsupervised Classification does not seem to have any documentation on the convergence threshold used in the tool. To compare, Erdas Imagine has all of the necessary ...
user avatar
  • 50.3k
9 votes
0 answers
4k views

Exporting GeoTIFF raster to GeoPandas dataframe

I'm just starting in the field of GIS (mostly worked with just python before) and got stuck on a problem. I'm looking for a way to polygonize an already masked GeoTIFF raster with population data in a ...
user avatar
  • 201
9 votes
0 answers
183 views

Intersections in linestrings using PostGIS

I need to get the intersections of streets and create a graph, so to get the intersections I use this select: SELECT ST_GeometryType(geom), geom FROM ( SELECT a.gid, ST_Intersection(a....
user avatar
9 votes
1 answer
5k views

Filtering a layer based on property that's an array in with Mapbox GL JS?

I've got a relational dataset broken into two layers: members and organizations. They're GeoJSON, with features that look something like this: // Org Features { "type": "Feature", "geometry": { ...
user avatar
  • 526
9 votes
0 answers
708 views

Grouped "labels" for QGIS 3.0 Point Cluster styling?

I'm trying to make a cluster visualization of a vector point layer about trees with a few requirements: The clusters need to change depending on zoom level (solved) The clusters need to indicate how ...
user avatar
  • 113
9 votes
1 answer
2k views

QGIS GRASS Processing Not Working on MacOS?

Recently upgraded to QGIS3 (3.0.2) for MacOS (High Sierra) and encountered GRASS (7.2.2) issues. Tried adding a custom variable and now when running GRASS algorithms (e.g. r.reclass) I get the ...
user avatar
  • 91
9 votes
0 answers
440 views

QgsRubberBand Move Event

I have created a QgsRubberBand which copies feature from layer. I need to be able visually move this rubberband on mouse event 'move'. Actually same visualisation like during self.iface....
user avatar
9 votes
0 answers
493 views

Removing overlapping features by percentage in PostGIS

I have geometry records of type MultiLineStringZM and I am trying to INSERT new records that overlap some of the records currently in the table. If they were type MultiPolygon I could use ST_Area() as ...
user avatar
  • 695
9 votes
0 answers
3k views

Get rid of jumping GPS data with pykalman

I have gps data that I get from a smartphone application. Whenever the smartphone is stationary, the gps points are jumping. I understand that the signal is inaccurate due to the reception in a city ...
user avatar
9 votes
1 answer
1k views

How to access Google Earth Historical Tiled Imagery Url to other Map APIs or Cesium.js?

Does anyone know how to access Google Earth Historical Tiled Imagery url? Then, the users can load the xyz tiled imagery by using different map APIs such as OpenLayers 3, Leaflet, and Google Map APIs ...
user avatar
9 votes
0 answers
2k views

How to prevent cross-world lines in ggplot world map?

I'm having issues displaying 'great circles' paths and polygons in ggmap, an extension of ggplot2. Please enter the following code to replicate my issues: https://gist.github.com/Robinlovelace/...
user avatar
8 votes
0 answers
221 views

Projection: Mollweide to Equirectangular

I am trying to reproduce in Python a coordinate transformation of a map from Mollweide coordinates (see Figure A) to Equirectangular coordinates (see Figure B) that I saw done in Mathematica in the ...
user avatar
8 votes
0 answers
67 views

Regex_replace in the Field Calculator: unexpected duplication of replacement elements

After testing things out for a different question, I found something unexpected about the way regex_replace works in the Field Calculator, compared to PostgreSQL. The suggested insert ends up ...
user avatar
  • 2,769
8 votes
0 answers
75 views

Finding geodesically flat regions in DEM data

I'm interested to find regions in some DEM data for Earth that are what I call geodesically flat, i.e. flat in the way that the path light travels is flat in the absence of strong gravitational fields....
user avatar
  • 191
8 votes
0 answers
114 views

QGIS vector field marker not respecting map rotation

I’m working on a map the shows point displacement between two dates. These are survey benchmarks that are surveyed periodically to observe slope movement. Symbolizing this in QGIS is straight forward ...
user avatar
8 votes
0 answers
85 views

Does QGIS use data source-specific operations?

This may be a very basic question, but I couldn't find an appropriate answer. Does QGIS use data source specific operations where available and appropriate? For example, when using the Join attributes ...
user avatar
  • 346
8 votes
0 answers
131 views

How does Empirical Bayesian Kriging of ArcGIS Pro handle sampling bias?

In ArcGIS Pro, simple kriging approaches allow you to de-cluster your data before applying a normal-score transformation. According to the Esri guideline, normal-score transformations are only ...
user avatar
  • 99
8 votes
0 answers
194 views

Naming clipped layer according to the attributes of the mask layer in QGIS

I have calculated the dnbr for a fire season across a whole region, and I've clipped it using a mask. The mask is a layer of ground survey plot locations because I want to find out the dnbr for each ...
user avatar
  • 81
8 votes
1 answer
491 views

How to use a custom function inside GEE ee.Reducer?

I have generated a segmentation using SNIC on GEE and calculated some statistics/features for each segment, using ee.Reducer e.g. mean, std, median, etc. I want to calculate more features based on my ...
user avatar
  • 337
8 votes
0 answers
180 views

How to uncompress a file geodatabase with open-source tools?

At 3.10.4 I tried to load a FGDB polygon feature class, but it failed, with an "Invalid Data Source" error. I tried the load with both the Vector > Directory > ESRI FileGDB and Vector > Directory > ...
user avatar
  • 7,049
8 votes
0 answers
137 views

Does the projection of a PostGIS table affect the rendering speed in QGIS?

I am interested to know whether changing the projection of a PostGIS table will affect the rending speed when viewing it in QGIS. I have two layers coming from QGIS which are exactly the same and ...
user avatar
  • 2,738
8 votes
0 answers
275 views

OGR failing to unpack polygons and respective holes from shapefile

I'm trying to unpack shapefiles in Python (v3.7.4) using the GDAL-OGR library (v2.3.3). Each shapefile has only one feature containing multiple polygons with holes. They cannot be produced differently....
user avatar
8 votes
1 answer
716 views

Finding the closest line to polygon using Python Rtree

I have a series of fields and roads. I am trying to find the nearest road to each field. I want to add field to each of my polygons with the index/name etc. of the closest road. Would this be the ...
user avatar
  • 321
8 votes
0 answers
969 views

Nearest neighbour joins for two geodataframes using KDtree from scipy/sklearn

I have a number of large geodataframes and I want to automate the implementation of a Nearest Neighbour function using a KDtree for more efficient processing. The process I want to achieve here is to ...
user avatar
  • 81
8 votes
0 answers
91 views

Snap LineStrings considering direction in QGIS 3

I have 2 projected shape files: Roads (red) and public transit routes (blue): I want to snap the PT routes to the roads, but because of inaccurate marks sometimes the routes are snapped to the wrong ...
user avatar
  • 357
8 votes
0 answers
117 views

Referencing an output in an expression in process modeler

In the process modeler, I'd like to reference an output of a previous step as one of the parameters of an algorithm. In this case, the previous step was clipping a large raster and I want to use the ...
user avatar
8 votes
0 answers
2k views

QGIS 3.4 and loading raster from multiple variable NetCDF file

Using QGIS version 3.4.4 when loading a NetCDF file out.nc which contains multiple variables on a fresh Ubuntu 18.04 install I encounter the following error: CRITICAL Invalid Layer : Raster layer ...
user avatar
  • 161
8 votes
0 answers
822 views

Add private plugin repository to QGIS 3.4

I want to add a repository to my QGIS 3.4 which is on a private server. The repository contains all files needed (plugin.xml and metadata.txt for example) and has the structure as described here: Is ...
user avatar
  • 495
8 votes
0 answers
1k views

Using WFST in Leaflet: can not move/delete features

I write a Leaflet app which makes use of two plugins Leaflet.Draw and Leaflet.WFST. The first allows to create/edit/delete features, the second saves changes to my PostGIS database hosted by GeoServer....
user avatar
8 votes
0 answers
246 views

Equal length dashed lines while using 'segments_to_lines' in QGIS

I want to create tapered lines with a dashed line stroke (to style intermittent streams). I followed this tutorial to create the taperered lines, basically using Geometry generator with the expression ...
user avatar
8 votes
0 answers
1k views

Getting Spyder IDE to work with QGIS?

I was hoping someone could help me get Spyder working with QGIS. I am finding the python editor limiting within QGIS as I would like to debug my code, use the variable explorer, and be able to run ...
user avatar
  • 81
8 votes
0 answers
247 views

Position of vehicles relative to lead vehicle

I have a set of vehicles (think railway) that are in a (semi)fixed formation. I know the lead vehicle and I know the GPS coordinates of the lead vehicle at any given time. Sometimes, I can rely on the ...
user avatar
  • 181

15 30 50 per page
1
2 3 4 5
663