# Tagged Questions

A mathematical procedure used to solve problems with a series of steps. Algorithms are usually encoded as a sequence of computer commands.

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### How to convert building outlines to Polygons?

I have line vector layer which contains contours of buildings in the form of separate segments. I want to convert lines to polygons (QGiS 2.17) but it doesn't work. I'm trying to solve this problem ...
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### Orthophoto generation algorithm

I want to generate orthophoto from images captured from UAV. As input I have "point cloud" GPS coordinate + RGB color of points, is it enough information for orthophoto generation? I'm looking for ...
22 views

### The method of calculating geodesic distance of Caris Lots [closed]

I'm trying to understand the method of calculating geodesic distance and area using Caris Lots Base Editor, because I need to compare the method between ArcGIS Engine and Caris Lots I tried to find ...
32 views

### Optimizing placement of several points enclosed by polygon from certain features?

I wish to find a way to optimize the placement of 5 points which are enclosed by a polygon. The optimization should be in a way that there is a minimum distance between the 5 points. 300 meters ...
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### walk me through tdoa [closed]

I'm working on a TDOA application. This is just something in my free time to see if my hardware can accurately do it and it sounded like a cool challenge. Regardless if it looks possible or not, I'm ...
63 views

### How To Properly Implement a Bounding Box for Shapely & Fiona?

I am trying to spatially analyze two layers within same GDB file using Python / Shapely. Another user was kind enough to give me a procedure to go by in trying to reduce the number of senseless ...
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### Spatially Analyzing two layers within same File Geodatabase using Python / Shapely?

I'm using a nested for-loop to do Shapely analysis between two Python lists created via two pre-reads of the same GDB file. One list contains all the features of a particular layer while the other ...
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### Wrap the set of points to the minimum polygon

Given I have a set of points which represents the circles which are intersected. As result I'm trying to receive the boundary which represent the polygon which wraps all circles. Please take a look ...
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### data for radius search in shortest path finding?

Is there any way for getting data for radius search ( described here: http://orsnz.org.nz/conf36/papers/Engineer.pdf [ Faramroze Engineer Department of Engineering Science University of Auckland ...
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### Algorithm for converting from projected coordinate system to geographic one using Helmert transformation

I have a data in projected coordinates system and I need to convert them to WGS84. I know the parameters of position vector transformation and I know the projection details of my projected coordinate ...
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### Is it possible to stop an algorithm midway through processing in QGIS?

This question come about do to an annoying though infrequent issue I have been having in QGIS. On occasion, I will begin processing a tool that will take some time to run but realize midway through ...
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### Algorithm to simplify a Polygon/Series of Points to a given number of Points

I have a polygon (or let's call it just a series of points). I want to simplify it (reduce the amount of points) to a given number of points. Currently I use Douglas Peucker and try to guess the ...
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### How to add my own algorithms to ArcGIS toolbox [closed]

I want to implement and test some algorithms for line generalization tool in ArcGIS software by Python programming, but I do not have any access to its tool bar script. My question is, how can I add ...
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### Packing polygons without intersection and empty places [closed]

How can I pack polygons without empty places and intersections? Please tell me everything that might help me (API, algorithms, etc.) I'm using: USPS API to get carrier routes. dbscan.js to ...
276 views

### Generalization algorithms [closed]

Does anyone have the proper codes for line simplification and smoothing algorithms which is good to implement instead of ArcGIS algorithms? For example any of these: Visvalingam–Whyatt Reumann–...
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### Optimum Path finding (for Cross Country Movement) using TIN (Triangulated Irregular Network)

I am working on path finding algorithm (using A*) for cross country movement (not for road movement) on map using grid based approach. Algorithm supports path calculation considering slope of terrain. ...
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### QGIS: Release file lock on file used in a processing algorithm at the end of script

I am using runalg (qgis:joinattributesbylocation) on two QgsVectorLayer objects. At the end of my script I'm trying to delete all the files created during the script. I can delete everything except ...
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### C# selecting map tiles from user defined rectangle points?

I have a WPF user control with which the user can draw a rectangle on the map canvas to define an area for downloading background imagery tiles from a web service. The tiles are in Lat long 1x1 degree....
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I have a POSTGIS database with geography points and i want to cluster the points using quad-tree . I have a map where i have to display the markers clustered or non clustered depending on the zoom ...
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### Process road polylines to not overlap building polygons

Is anyone aware of a processing tool in Grass or similar which will find segments of polylines which overlap polygons in another dataset and reroute the polyline to avoid the collision? My problem is ...
52 views

### How to divide line into three equal parts?

I have a problem with line division. I'm writing a program in JS/C++ generating KML files. I was trying to divide a line using my own function (which is correct on cartesian space): var part1Lon ...
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### Is there an R package for finding the maximum-area rectangle in a non-convex polygon?

Does anyone know if there is an R package out there with an algorithm which finds the largest rectangle within non-convex polygons? I have Googled, searched the R Sig Geo archives, and looked here on ...
154 views

### Given two lat/longs, how can I tell if they are within 1 mile of each other?

I'm trying to implement a very efficient check to see whether two points are within a mile of each other, or not. My current approach is to compute the Haversine distance, and then check to see if it'...
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### Algorithm used by location-allocation (Maximize Coverage problem type)

Which algorithm does the location-allocation Maximize Coverage problem type use? I already found on the ArcGIS help that location-allocation uses a vertex substitution heuristic to solve the p-median ...
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### What would a simple hillshade algorithm be?

I'm curious how GIS systems actually generate a hill-shade from input data like a raster DEM layer. I'd like to implement my own in software (mostly for fun/learning) but I want to start with a ...
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### Pseudo code to correct Geographic points for UTM Easting distortion on Web Mercator Projection

I have chosen to use a Web Mercator projection system for: Use of Tiling system for low memory usage Accessing only one site/area at a time Reuse of Google Tiles - for many sites In some cases I ...
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### Diagram Ring Elements Locator (Tough Problem)

I asked http://stackoverflow.com/questions/35579843/get-only-ring-nodes-from-a-diagram on stack overflow but there was no help at all. So I hope I get help from someone on here :) I have a diagram ...
128 views

### Possible point location algorithm

I need to calculate possible point location based on its speed and some other factors. For example, there is a man in the middle of the forest and I need to calculate his possible location at some ...
258 views

### What algorithm does QGIS use to calculate Nearest Neighbor Index?

I'm carrying out nearest neighbor analysis on a set of geological features in QGIS, trying to find out whether they're clustered or not. I've calculated the nearest neighbor distances using the '...
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### How to check based on GPS coordinates if point is near a given path? [closed]

Path is just a straight line defined by coordinates of the beginning and end of it. My coordinates are simply longitude and latitude of three points: start of the path end of the path my point (for ...
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### Creating 30 areas with equal amount of road in an irregular polygon

The result should be something like this just more polygons. Does anyone know about a tool, which given a table, can create a number of polygons which will divide the tables object into, for ...
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### GPS coordinates of a point between two known points

I am looking for an algorithm for finding GPS coordinate of a point on a straight line defined by say points p1 and p2 at distance r from p1. GPS coordinate of p1 and p2 are known. I searched a lot on ...
197 views

### Road segments reconstruction from GPS trajectories

We have a 10,000 base of vehicle mounted moving devices which report their GPS position on a time based schedule. All that data is currently being stored in our database for several business related ...
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### using a linear solver to get a “centre of gravity” of a set of points

As a programmer, if I have a linear solver available. How can I formulate the following problem as a set of constrains / decisions / goals for the linear solver? I have a matrix of say 10*10, so 100 ...
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### Need to find a point a given distance along a linestring

Need to take a linestring and find a coord every x meters along the line. I tried using the SQL Server Spatial Tools and found .NET to be slow and after 5(ish) days of processing, SQL server (or .NET) ...
143 views

### How to split osm data

I have a gigantic OSM geodata file of a city, and I want to split it into smaller files according to each group of tags. I googled it up and i found that there is a jar file caller splitter.jar . i ...
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### Explaining different results from Ordinary Kriging and Universal Kriging?

When using either methods to create a surface from the same set of observations, these surfaces differ from each other. Visually it can be seen in the differences of the following contours (...
101 views

### Algorithm for spatial clustering?

I have a series of 2D maps with values ranging 0.0 to 1.0 spread all over. The algorithm that produces them is an application of the fractional Brownian motion. Each map measures 101x101 pixels or ...
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### QGIS crash while delete duplicate geometry

I have a polygon shape with nearly 60 000 features (at around 3 000 square kilometres) in QGIS 2.12. I try to delete duplicate geometries from this layer and the algorithm runs until 99%. Then QGIS ...
61 views

### Calculate location on line with known azimuth to point

I have the following situation (consider distances up to 300m - without great circle etc. affects): How can I calculate the unknown location when I have all other locations in the triangle and ...
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### Algorithm to realize monotone polyline?

I'm searching about the algorithm helping me realize monotone polyline. I would wonder if anyone has any program realizing monotone polyline.
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### Geological map generalization polygon aggregation

I am working on generalization of Geological maps and the first thing I am wondering about is aggregation of separate patches that may have same class and which are closely situated to each other. ...
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### Travel planning - Finding farthest points of a polygon

I’d like to organize a tour around the lake with 2 objectives: maximise the length of shores to view minimise travel distance In order to do so I can: Pick 2 most remote points on the lake in ...
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### Convert moving duration into routes

Which algorithm, that is based on open Street map takes the current GPS position, a duration and an average speed or way of transport(by foot, by bike or by car) and outputs possible routes, that ...
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### Create a center node based on both polygon and line shapefile

Sorry for cross posting. I want to develop a node layer from two other layers. One of the layers is a polygon contains a series of zones. Another layer is a line layer of roads. The nodes I want to ...
146 views

### Geofencing Issue (Leave/Enter geofence Timing Issue)

I already search SE already if the question has been raised before but I can't find one so I'll ask here anyway. I'm creating a small application which involve geofencing my GPS device doesn't have a ...
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### How to find the most accurate street/road by a given coordinate and some previous locations?

I'm building an application that gets user's position and tracks its changes while driving providing some information stored in shape file. To get the most accurate information from this shape file ...
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### Calculating intersection between lines with GeoTools (java)

I have ArratList<Segment> (N segments - array size is N) when: public class Segment { Node vertex_1; Node vertex_2; } public class Node { double latitude; double longitude; } ...