All Questions

14
votes
0answers
360 views

SNAP vs. GDAL vs. Orfeo - image rescale, histogram cut

I work with a Sentinel-2 .jp2 image (red band, 10950 x 10950 pixels). My aim is to reach the same result what SNAP does with a Python script. See the SNAP method and parameters: So this is my ...
14
votes
0answers
355 views

Determining flow path length in QGIS?

I need help with qgis flow path length. I try to run the program and when I run the program I get a raster with 0 values, as input I'm using filled raster, I don't now if I'm doing something wrong or ...
14
votes
0answers
956 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 ...
13
votes
0answers
364 views

rMaps choropleth with custom json

With R I want to make an animated choropleth map with the rMaps package and a custom map. I tried to follow the example of Diego Valle described here and to use the custom map info for Datamaps. ...
11
votes
0answers
220 views

Showing startup-messages on QGIS splashscreen

During the startup of QGIS there are status messages shown in the lower part of the splashscreen like "restoring loaded plugins". I am using a startup.py from which I would like to inform the user ...
9
votes
0answers
140 views

Options for generating travel time isochrones in QGIS 3.4: what do you use?

I'm currently using the updated OSM tools to generate isochrones in QGIS 3.4, which works well (example below). My question is just what methods other people use and whether there is something better ...
9
votes
0answers
228 views

Cannot Open VRT of Sentinel2 image created by AutoCreateWarpedVRT

I am trying to create a warped VirtualRaster of a Sentinel2 image. Here the Python code I tried: from osgeo import gdal, osr srs = osr.SpatialReference() srs.SetFromUserInput('EPSG:32632') gdal....
9
votes
0answers
702 views

Why does @data@values slot for RasterLayer only contain logical(0) and not the actual values?

Trying to get to the bottom of why, when I read in a raster of NDVI, the @data@values slot does not contain the actual values until I set them manually. For example: NDVI <- raster("./filename....
9
votes
0answers
517 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, ...
8
votes
0answers
257 views

Alter Minimum Bounding Box Algorithm

I'm trying to create an algorithm similar to minimum bounding box (though it may end up looking nothing like it). In this case the angle will be passed as a parameter and given the angle I need the ...
8
votes
0answers
244 views

QGIS 3 and SAGA 3.0+ Integration

I've looked all over the net and I'm wondering if there are any plans by the QGIS developers to integrate some of the newer versions of SAGA available in the repository and as binaries on the project'...
8
votes
0answers
250 views

Calculating new field works inside QGIS Python console but not in standalone program

My code in the standalone program import sys sys.path.append("C:/OSGeo4W64/apps/qgis-ltr/python/plugins") from qgis.core import * from PyQt4.QtCore import * from PyQt4.QtGui import * import ...
8
votes
0answers
156 views

Remove “Save As” from QGIS Context Menu Using PyQGIS

I want to remove an Existing Option ("Save As") from context menu of QGIS layer, what I have found so far is, to add new action in the LegendItems, or overwrite completely with new options. But could ...
8
votes
0answers
252 views

Executing bidirectional dijkstra on TIFF image?

Can anyone indicate an example of how to do this? Link, tutorial etc... I started a discussion here about how to load a TIFF image like a graph nicely answered by @sehe. But, in this post the image is ...
8
votes
0answers
164 views

Matching segments of different lengths

I'm trying to match small segments with a larger segment they are the most probably related to: relatively close, similar bearing, and facing each other. Here is a typical example of the data I have: ...
8
votes
0answers
621 views

How do I simplify the straight sections of (multi)Linestring in PostgreSQL/PostGIS leaving the curved sections untouched

I have (multi)linestrings containing upwards of 5000 points and I want to perform two simplifications possibly using Ramer Douglas Peucker or alternative methods in PostGIS The (multi)linestrings ...
7
votes
0answers
148 views

Missing roads from OpenStreetMap data with osmosis

I am currently trying to extract road networks from OpenStreetMap dumps downloaded on Geofabrik. I am using the following osmosis (version 0.45) command to extract roads: osmosis \ --rbf input.osm....
7
votes
0answers
156 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 ...
7
votes
0answers
148 views

Buffered one-to-many spatial join QGIS3

I'm trying to spatial join bus stops and census block groups. However, these are a bit tricky with walking distance. Many bus stops are right on the borders of census block groups or within walking ...
7
votes
0answers
87 views

Does PostGIS ConcaveHull exclude points/polygons in some cases, and buffer outward in others?

In trying to generate concave bounding polygons using PostGIS ConcaveHull, I am seeing what I think is strange behavior. When running with a 0.99 tolerance, the resulting polygon shrinks tight as ...
7
votes
0answers
457 views

Rasterio does not execute the rasterize function

Rasterio's features.rasterize() function is not working as expected. I have two files: OpenStreetMap shapefile with land usages Raster (.tif) with satellite imagery Goal: Create a raster file from ...
7
votes
0answers
91 views

Open WMTS query parameter encoding with “+” character in QGis

I am trying to create a WMTS endpoint with query parameters in the urls that contain a + character. So my resource url looks like this: <ResourceURL format="image/png" template="http://localhost/...
7
votes
0answers
188 views

Is it possible to open MapGIS files ( .WL, .WP & .WT ) in QGIS or other GIS?

We received some files from clients located in China created in a program called MapGIS. I was wondering if anybody knows how to make QGIS or any other GIS program, excluding MapGIS, open these files? ...
7
votes
0answers
790 views

How can I merge adjacent polygons and return all (adjacent and not adjacent) as Multipolygon?

I have a postgres database with administrative boundaries and their geometry. Each of those boundaries have an ident number. What I want to achieve: First I want to select all rows which are ...
7
votes
0answers
1k views

How to force geometry type in mixed geometry WFS layer in QGIS?

I have an external WFS source serving mixed geometry types - in other words, I have no control of the source. When adding the layer QGIS sets the geometry type to line and thus I am unable to style ...
7
votes
0answers
1k views

Evaluating map projection scale error

This is related to a previous question I posted. I am trying to quantitatively evaluate scale distortion associated with choosing different projection center, center azimuth, and scale factor values ...
6
votes
0answers
73 views

Stopping never ending QGIS processes instead of forcing QGIS to quit?

being a new to using QGIS on an iMac I often start processes on a large data-set that sets the spinning wheel in to a never ending state. I often need to force quit the whole QGIS program to break ...
6
votes
0answers
285 views

Editing Layout-Items after loading a QPT-Template in QGIS 3 with Python

I am facing a problem with the new Layout API while implementing a plugin for QGIS 3. Starting point is a layout template in qpt-Format, which contains different elements like (attribute) tables, map, ...
6
votes
0answers
220 views

Different results from GDAL raster attribute table command on mac and windows

I am trying to get the raster attribute table of the following file: Shift_cult_past_current_prediction_20160107_gr1DD.tif available here: https://www.dropbox.com/s/fmomfpro3j6dmz8/...
6
votes
0answers
493 views

Gdal and module import error when creating an .exe application with pyinstaller

I’ve been struggling since three days in a row to create a windows executable application from my python application. I have managed to get results but I’m not at all satisfied with the workarounds I ...
6
votes
0answers
161 views

QgsSpatialIndex partial or complete overlap

I'm working on adding some functonality to a QGIS plugin. It currently uses a QgsSpatialIndex to efficiently compute whether the features of a vector layer intersect (potentially millions) of ...
6
votes
0answers
5k views

Queen vs Rook neighborhood

Queen and rook neighborhoods are two common ways to calculate statistics for a focal cell. They are also known an Moore and (von) Neumann neighborhoods. I think a "bishop version", i.e. from lower ...
6
votes
0answers
435 views

QGIS 2.8 Python Plugin Unittest Segmentation Fault 11

UPDATE: This issue may be isolated to my MacBook. The seg fault did not occur in testing on Windows. I have put together a sample unit test for a QGIS python plugin. It is causing a Segmentation ...
6
votes
0answers
656 views

Efficiently calculate distance between raster patch edges

I have a binary raster which I've classified into patches using raster::clump. I now want to efficiently calculate the edge-to-edge, i.e. minimum, pairwise distance between patches. I am currently ...
6
votes
0answers
899 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 '...
6
votes
0answers
4k 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 ...
6
votes
0answers
2k views

Rasterize shapefile using another raster's size and resultion

Rasterizing a vector (shp) I face the following problem: I want my output file (the rasterized vector) to have the same resolution and dimensions as an existing raster. If I understand the interface ...
6
votes
0answers
354 views

Accessing existing instance of QGIS from stand-alone python script

For my own data analysis pipeline, I am running a split screen setup with iPython notebooks on one side, generating variables from source data, pushing them to a CSV file which QGIS then reads/joins ...
6
votes
0answers
844 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. ...
6
votes
0answers
1k views

Uploading raster format(*.tif) to postgis through raster2pgsql

I'm new to postgis and raster file format. i currently working on netcdf files and i want to import it into postgis through curl command line tool but its failed for me.so i jump on to GDAL v1.9.2 ...
6
votes
0answers
146 views

Is IGraphicTracker leaking memory?

It seems that when geometries are removed from an IGraphicTracker instance, the geometries remain in memory until IAoInitialize.Shutdown() is called. I have tried removing the geometries by calling ...
5
votes
0answers
38 views

Coarse Woody Debris extraction

I created very high dense point cloud of some forest plots using terrestrial laser scanner. Then removed points above 1.3 meter to see the coarse woody debris (Fallen dead trees). Attached is the ...
5
votes
0answers
33 views

Shp2pgsql encoding issue / error. Special latin /utf characters (áéíóú) are wrong

I am not able to load accented vowels coming from a Shapefile, to a PostGis geodatabase. This is my information: Operative System: Windows 10. PostgreSql Database: postgresql-10.5-2-windows-x64.exe. ...
5
votes
0answers
104 views

Unattended QGIS updates with OSGeo4W

I would like to do an unattended update of my QGIS install every night using windows task scheduler. Is it possible to automatically update all installed packages with the OSGeo4W-Installer without ...
5
votes
0answers
101 views

QGIS versions yielding different results on $area calculations?

When grading an exam, I discovered that QGIS 3.2 and 3.4 produce different values on computing $area over polygons. I experimented using $area and area($geometry) to check the differences between ...
5
votes
0answers
30 views

Can QGIS 3.0 identify tool give labels as well as band values for selected raster pixels

I'm using QGIS 3.0 for comparison of several landcover grids. These have a set style with 72 categories of landuse. The Style menu allows you to give a text label for each value within a band. The ...
5
votes
0answers
128 views

Drawing geometrical shapes with dimensions using ArcGIS API for JavaScript?

I have to draw the geometrical shapes with their dimensions and show it with that shape. As in below images, I want to show the length and width of the rectangle, the radius of the circle and the ...
5
votes
0answers
127 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....
5
votes
0answers
139 views

GDAL grid Not recognizing csv as having geometry

NON-DUPLICATE EDIT: This question is not a duplicate because I have tried the solution presented as the answer to the "original" question and it did not work. See results below. I am attempting to ...
5
votes
0answers
207 views

Execute SQL in QGIS Graphical Modeler

I'm trying to sort a shapefile by one of its attributes using "Execute SQL", in the QGIS Graphical Modeler. Using a vector as input is working fine, but when I use a layer generated by an algorithm ...

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