Unanswered Questions
15
votes
1answer
765 views
How to reverse-georeference with QGIS?
I have a map with a "strange" projection (it's basically hand-painted, not an exact one). I can easily georeference it in QGIS using the Georeferencer plugin and the Thin Plate Spline transformation ...
11
votes
0answers
127 views
Accessing the internal data structure storing Postgis spatial index (PostGres GiST)
I am curious about how the internal data structures and storage mechanism of the spatial GiST index in Postgis. In Oracle, I used to like to show how the SDO indexes were "just another table", and how ...
11
votes
0answers
300 views
How to extract sublinestring from a linestring with overlapping segments
Problem statement:
Given a bus route (defined as a linestring ln.the_geom), and a set of bus stop locations (pt1.the_geom,pt2.the_geom,...ptn.the_geom), divide the bus route into segments between bus ...
10
votes
2answers
905 views
Histogram Matching using Python to improve mosaicking process of multiple overlapping rasters?
I am trying to do histogram matching using Python to improve the mosaicking process of multiple overlapping rasters. I am basing my code on that found at:
http://www.idlcoyote.com/ip_tips/histomatch....
10
votes
0answers
249 views
Joining layers with respective elements with PostGIS Topology
I'm currently using PostGIS topology extension, but I have some difficulties in understanding how the structure works:
One of the key points is the use of "layer"s: as of what I understand, features ...
10
votes
0answers
744 views
Grouping analysis of points to divide polygon into n number of sub-regions using QGIS?
I'm attempting to create n sub-regions from a polygon based on a cluster analysis of a bunch of overlapping raster layers (physical layers, eg: depth, currents, waves).
Briefly, I can create a ...
9
votes
0answers
110 views
Development of a plugin which depends on an external Python library
I'm developing a Python plugin, the target is integrating into QGIS the functionalities of a PyPI Python library called 'elevation'.
Is there an OS independent way of installing external Python ...
9
votes
3answers
711 views
Importing KML and style information into Geoserver
So I'm working on a project that's been in development for over a year, but I only recently got involved. My task involves converting roughly 2,500 KML files into another format, importing these files ...
9
votes
0answers
226 views
Spatial query too slow to handle bigger OSM extracts
I'm trying to compute some statistics for OSM data using PostgreSQL 9.3.5 and PostGIS 2.1.4. I started with a small bavaria extract which I downloaded from Geofabrik. The db schema is the normal API 0....
9
votes
0answers
2k views
Polygon creation (Clockwise rotation or not)
According to "ESRI Shapefile Technical Description An ESRI White Paper—July 1998", Vertices for a single, ringed polygon are, therefore,always in clockwise order. Otherwise,"Dirty" polygons occur when ...
8
votes
1answer
90 views
How to undo field calculation in ArcGIS Pro
I am using ArcGIS Pro and cannot find a way to undo field calculations. With ArcGIS 10.x for Desktop, field calculations could be undone when an edit session was active, but Pro seems to be in a ...
8
votes
0answers
87 views
How to synch a FeatureTable with a FeatureLayer's selection set?
The ArcGIS Server JS API contains a new FeatureTable class, which shows the attribute table corresponding to a FeatureLayer. There is an option syncSelection which:
Enables an interaction between ...
8
votes
1answer
68 views
Seeking public database to input date and city to determine country at time and present-day?
I'm looking to automate a common task for us. For example, Jaromir Jagr was born in Kladno in 1972. I want to be able to take that and output a string.
Born in Kladno, Czechoslovakia (present-day ...
8
votes
0answers
186 views
How to access a deleted features attributes (before committing)
I have a signal setup for a feature deletion event on a layer:
self.layer.featureDeleted.connect(self.feature_deleted)
When I try and grab an attribute from the deleted feature on the slot, a ...
8
votes
1answer
228 views
PostGIS Recursive Query Based on Line Connectivity
I'm having difficulty with a query. I have a network of linestrings, each with a value in the n_type column. This can be one of a handful of options. I'd like to generate a new table that groups any ...
