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24
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759 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 ...
21
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 ...
12
votes
0answers
497 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 ...
11
votes
0answers
137 views

QGIS Print Layout - Rotation of Grid Coordinates to match map rotation

I have a layout in QGIS where 3 map views are rotated to 35 deg. The grids automatically rotate to match the maps rotation, however the labels do not. Does anyone know a way to make the coordinate ...
11
votes
0answers
924 views

Digitizing in stream mode in QGIS, using a tablet?

How to 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, ...
11
votes
0answers
654 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, ...
10
votes
0answers
118 views

Is there a way to create quadrilaterals buffers around polygons in QGIS?

For a little map project of mine, I need to create quadrilaterals around a polygon feature based on the bisected angles of the vertices of that feature. Here is an example: Is it possible to automate ...
10
votes
0answers
141 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 ...
9
votes
1answer
342 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....
9
votes
0answers
373 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 ...
9
votes
0answers
297 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
282 views

Open QGIS project files in exclusive mode / alert if project file already in use

I have QGIS-Project-Files saved to a network drive and was wondering if it is possible to warn users that a project file is already opened by an other user to prevent concurrent editing of the same ...
8
votes
0answers
309 views

Point cluster symbology for different categories without overlapping symbols

I'm trying to visualize crimes based on if the crime happened during day or night time. I've tried using the point displacement tool but I'm not satisfied with the results because the readability for ...
8
votes
0answers
1k views

How do I export 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 16bit image, as 8bit is giving a terracing effect.I believe I ...
8
votes
0answers
237 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 ...
8
votes
0answers
1k 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 '...
8
votes
2answers
4k views

C# implementation of concave hull / alpha shapes

I'm looking for a C# implementation of the Concave hull (alpha shapes) algorithm. I already found several Java, Python and C++ implementation but no C# version. The other implementation are quite ...
8
votes
0answers
5k 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 ...
8
votes
0answers
2k views

Rasterize shapefile using another raster's size and resolution

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 ...
8
votes
0answers
995 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. ...
8
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 ...
7
votes
0answers
212 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. ...
7
votes
0answers
477 views

Splitting polygon into equal area's polygons in QGIS 3.6?

There is a plugin in QGIS 2.18 called 'Polygon Divider' which divides an irregular polygon into smaller equal area's polygons of a specified/custom sized but in QGIS 3.x version there is no 'Polygon ...
7
votes
0answers
116 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 ...
7
votes
0answers
627 views

How to use ATOM FEED Data in QGIS 3.6.1?

I would like to know how I can work with ATOM FEED Data in QGIS. In ealier QGIS versions this worked with the Plugin "INSPIRE ATOM Client", but this Plugin doesn't work in the current version. An ...
7
votes
0answers
166 views

Using Layer Parameter variables in Field Calculator within QGIS Model?

If I define a Vector Layer as an input parameter to a QGIS model, then the parameter name is exposed as a variable in a Field Calculator within the model, however I am unable to use this variable as I ...
7
votes
0answers
150 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 ...
7
votes
0answers
253 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
202 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 ...
7
votes
1answer
223 views

Spatialite KNN view in QGIS

My task is to calculate the average ground survey level for each tree in my dataset, using the 3 closest survey points (optionally within a 3m radius of the tree). I want to write this in a Spatial ...
7
votes
0answers
326 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 ...
7
votes
1answer
532 views

Display pictures stored as bytea in postgresql column in qgis

does someone knows a possibility to visualize in a bytea column saved photos of a postgresql database in qgis? I would like to store pictures directly into the database, not just the link/ url.
7
votes
0answers
866 views

Landsat level-2 data comparison

I'm doing a temporal analysis of NDVI and temperature over 17 years, necessitating data from Landsat 5,7, & 8. I'm interested in using level-2 Landsat data available from https://espa.cr.usgs.gov/...
7
votes
0answers
1k views

Importing GPX data to PostGIS table

I'm implementing a recipe from Paolo Corti's PostGIS Cookbook (by the way, a great help!) in order to import track points from multiple GPX files into a PostGIS table in two steps (pages 87-88): 1 ...
7
votes
1answer
2k views

Clipping raster brick object in R

I have MODIS NDVI TIFF files for a year I want to first clip it with a irregular polygon (not by its extent only) of my study area and save it as a multi band raster in TIFF format The TIFF image are ...
7
votes
0answers
812 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 ...
7
votes
0answers
594 views

Steiner tree problem: Optimal routes for Fibre planning on road network

I am trying to solve a large optimization problem where I have a set of nodes on a road network that need to be connected using fibre using the shortest possible amount of fibre. The problem is a ...
7
votes
0answers
1k views

library for minimum bounding box “by width” in javascript or python

I'm looking for a library (or at least a code snippet) to calculate the minimum bounding box "by width" in javascript or python. Below is an illustration from the ArcGIS documentation of that ...
7
votes
1answer
346 views

Opening MOD17A3 in ENVI so it is properly georeferenced?

I am using ENVI 5.1 on Windows 8. I am trying to open a MOD17A3 (MODIS Net Primary Productivity standard product - L4) .hdf file which I downloaded from the USGS website. I am still a beginner at ENVI,...
7
votes
1answer
2k views

How to use MMQGIS hub lines tool in QGIS?

I am trying to connect source and destination points with the hub lines tool in mmqgis. I have gone through the other posts on this subject but couldn't figure out what I am doing wrong. I have ...
7
votes
2answers
2k views

Can I sell maps to third parties if I have Google Earth Pro License?

Not sure if this question is suitable for SE but I can't find answers anywhere else. I work as a GIS Analyst for a mining company that has its own GEPro license. As part of my job, I make PDF maps, ...
6
votes
0answers
41 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....
6
votes
0answers
225 views

Loading multiple shapefiles in GeoDjango?

I have 3 three shapefiles and would like to upload all of them and project the result in GeoDjango admin. a) state.shp (for the shape of a state) b) boundary.shp (to identify a specific portion in ...
6
votes
0answers
255 views

QGIS projects in PostgreSQL (pyQGIS - saving proj to DB)

I'm currently working on some code to automate the creation of a QGIS project from tables in a PostgreSQL DB. For info I'm working in QGIS 3.4. I'm almost there, but I'm stuck on one thing How do I ...
6
votes
0answers
96 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.geom, b.geom) as ...
6
votes
0answers
58 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 ...
6
votes
0answers
367 views

Fixed QGIS layer symbol size in layer legend

When a layer symbol is defined with map units or "meters at scale" unit, it is sometimes shown in the legend at a very small scale, preventing to see the details. Or if we zoom in the map, the legend ...
6
votes
0answers
415 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 ...
6
votes
0answers
200 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. ...
6
votes
0answers
530 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....

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