All Questions
32,745
questions with no upvoted or accepted answers
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 ...
- 5,562
17
votes
0
answers
817
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, ...
- 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 '...
- 469
15
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. ...
- 271
14
votes
0
answers
629
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 ...
- 22.4k
13
votes
0
answers
536
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 ...
- 136
12
votes
0
answers
393
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.
...
- 205
12
votes
0
answers
271
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 ...
- 555
12
votes
0
answers
504
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 ...
- 1,249
11
votes
0
answers
1k
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 ...
- 539
11
votes
0
answers
361
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 ...
- 1,217
11
votes
0
answers
296
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 ...
- 1,990
10
votes
0
answers
231
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 ...
- 1,385
10
votes
0
answers
534
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) ...
- 151
10
votes
0
answers
372
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 ...
- 2,131
10
votes
0
answers
460
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 ...
- 203
10
votes
0
answers
322
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 ...
- 7,763
10
votes
3
answers
891
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 ...
- 671
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 ...
- 50.2k
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 ...
- 201
9
votes
0
answers
190
views
How to do a Lee’s Tetrahedral Conformal Projection of Antarctic/South pole on QGIS?
I want to do map of Antarctic using the Lee's Tetrahedral conformal map projection as the image below using QGIS version 3.4. Is it possible to make a custom CRS to do it? If yes, what's the ...
- 121
9
votes
0
answers
179
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....
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": {
...
- 526
9
votes
0
answers
690
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 ...
- 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 ...
- 91
9
votes
0
answers
439
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....
- 165
9
votes
0
answers
476
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 ...
- 695
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 ...
- 91
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/...
- 4,094
8
votes
0
answers
63
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 ...
- 2,751
8
votes
0
answers
71
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....
- 191
8
votes
0
answers
108
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 ...
8
votes
0
answers
80
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 ...
- 346
8
votes
0
answers
124
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 ...
- 91
8
votes
0
answers
185
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 ...
- 81
8
votes
1
answer
471
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 ...
- 337
8
votes
0
answers
171
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 > ...
- 6,973
8
votes
0
answers
135
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 ...
- 2,728
8
votes
0
answers
267
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....
8
votes
1
answer
681
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 ...
- 321
8
votes
0
answers
916
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 ...
- 81
8
votes
0
answers
90
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 ...
- 357
8
votes
0
answers
115
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 ...
- 285
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 ...
- 161
8
votes
0
answers
813
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 ...
- 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....
- 356
8
votes
0
answers
243
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 ...
- 324
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 ...
- 81
8
votes
0
answers
243
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 ...
- 181
8
votes
0
answers
443
views
GDAL contour line generation at DEM edges
In a Python application I use gdal.ContourGenerate() to generate contour lines (GDAL version 1.11.4 and 2.2.1) from DTED tiles. DTED tiles overlap at the top and the right with neighboring tiles.
...
- 4,400