Unanswered Questions

29,681 questions with no upvoted or accepted answers
27
votes
0answers
2k 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 ...
17
votes
0answers
252 views

Unit testing for QGIS 3 plugins

There is a nice resource on unit testing for QGIS. There is also a post on this, Writing automated tests for QGIS plugins, which requires the use of docker and relies on QGIS 2 plugin - QGIS Tester. ...
17
votes
0answers
1k views

Digitizing in stream mode in QGIS using a tablet

How can I digitize in stream mode in QGIS, using a wacom cintiq tablet? Freehand it's no use. I need something like MNDR stream digitizing extension for ArcView 3.x, which allows continuous tracing, ...
15
votes
0answers
735 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, ...
13
votes
0answers
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 '...
13
votes
0answers
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. ...
12
votes
0answers
495 views

Producing time-space cube in QGIS?

Although I have seen many examples about doing this at ArcGIS Desktop, I am still trying to find a how to using QGIS. What I want to do is something like the image below.
11
votes
0answers
374 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 ...
11
votes
0answers
411 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 ...
11
votes
2answers
8k views

Downloadable, Open Source, IP GeoLocation database

I have an open source project I need a similarly open source IP GeoLocation database for. i.e. IP address to country (and ideally city). Ideally with a license that allows redistribution. This is a ...
10
votes
0answers
202 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 ...
10
votes
0answers
2k views

Exporting a 16-bit image from QGIS

Could someone explain how to export from QGIS a 16bit image? I have imported data and coloured it as I want, but need to export it as a 16-bit image, as 8-bit is giving a terracing effect. I believe I ...
10
votes
0answers
997 views

ogr2ogr (or other) simplification of polygons with shared boundaries

I am trying to simplify a collection of 100,000 or so polygons containing nearly 4 million vertices. The data is stored in a 2GB shapefile so there is no explicit representation of the topology ...
10
votes
0answers
1k views

Evaluating map projection scale error

This is related to a previous question How to determine projection parameters when customizing a projection I posted. I am trying to quantitatively evaluate scale distortion associated with choosing ...
9
votes
0answers
153 views

Reading raster backward using GDAL

I am currently working on two-scan raster algorithms (euclidean distance transformations, cost surface analysis, etc.). Those algorithms require a line-wise forward raster scan (from top left to ...

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