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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7
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114 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 ...
6
votes
0answers
399 views

Translate Orientation from Sensor data to Geo location

I am tracking a device that might loose GPS signal then and there. And when the GPS signal is too low, I should use the accelerometer and Gyroscope sensors data to guess which way they should have ...
5
votes
0answers
321 views

GPS data based track/trip calculation algorithm available?

Currently I'm receiving position data of moving assets every 90 or 120 seconds (depending on the asset). What I'd like to achieve now is to detect standstill and movement phases (tracks/trips) on the ...
3
votes
0answers
44 views

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 ...
3
votes
0answers
554 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 ...
3
votes
0answers
159 views

Is Hershbergers improved Ramer-Douglas-Peucker algorithim worth implementing?

Here is the article with code samples Other than the C code he wrote are their any implementations? Is it worth making a python or R module out of the C code? Are their known flaws to the algorithm? ...
3
votes
0answers
43 views

Clustering driven by an enum/list

Given a set of 2D points ( or vertices if you want ), the values stored for each point are: coordinate on x coordinate on y an enum or a value from a list in general for the sake of this example ...
3
votes
0answers
229 views

Pipe Network: Computing the inflows for systems with multiple reservoir (input source)

Let's say, for the sake of simplicity, we have the following Y Shape water pipe network: S1 and S2 are the reservoirs ( input source), Sout is the water demand where water is drawn out for ...
2
votes
0answers
23 views

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 ...
2
votes
0answers
25 views

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. ...
2
votes
0answers
41 views

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 ...
2
votes
0answers
66 views

Application of a Piecewise Logistic Function to Extract Seasonality Metrics

I am working with 16-day MODIS EVI (satellite) data and I want to fit a Piecewise Logistic Function through my 23 EVI data values. The following formula is for the Piecewise Logistic Function: y(t)= ...
2
votes
0answers
634 views

open-source code for the map matching algorithm

For map matching of the GPS data to the network data, there is a algorithm from Schussler, N. & Axhausen, K. (2009a). Is this algorithm released under open-source license ? Where can I find this ...
2
votes
0answers
206 views

ArcGIS - Flow Direction (Algorithm)

I am curious about the algorithm of Flow Direction in ArcGIS. Recently I am studying about Hidrology, and I have some questions regard to Flow Direction in GIS. The size of this cell is 100m x 100m, ...
2
votes
0answers
66 views

using MCA in GIS for suitability analysis

I have an essay about using MCD methods to solve suitability analysis. I must write a scenario about fuzzy membership, WLC and AHP. I feel that I’m confused about when and where to use each method. ...
2
votes
0answers
251 views

Free implementation of Polynomial Approximation with Exponential Kernel (PAEK) algorithm

I need a Free (i.e. Open Source) implementation of the Polynomial Approximation with Exponential Kernel (PAEK) algorithm, preferably in C, C++, Python, Julia or R. The algorithm is one of the methods ...
2
votes
0answers
198 views

How to detect turns of a route?

I'm doing a Python simulation of a vehicle, driving along a specified path. I generate dummy GPS readings, that fetch the current position of the vehicle, with some randomized error added. After a ...
2
votes
0answers
112 views

How to add nodes into graph

I'm new to qgis and in here I want to find a path between two selected points on the map(Roads-vector layer). The points are selected by the user, using mouse clicks. So here I used the astar ...
2
votes
0answers
75 views

What graph traversal algorithm should I use?

I would like to write an algorithm which can traverse a graph and hopefully later I can implement it to use for an indoor navigation system. The graph would come from floor plans of a building and the ...
2
votes
0answers
265 views

Iteration based positioning on Matlab - retrieving coordinates between iterations

This is my first question on SE so let me know if I'm not asking my question in the right place. So basically, I have an algorithm which uses UMTS measurement events for positioning estimation, which ...
2
votes
0answers
184 views

Placement of a fixed-radius circle on a sphere to maximize point containment

There are many papers on the "Circle Placement Problem" in 2D Euclidean space, but I haven't been able to find any papers discussing this problem on the sphere. The problem is: given a set of points ...
2
votes
0answers
1k views

Help with Shortest path Algorithm for enormous bus routes database

I am building a bus routes map for Chennai. I use Postgis. In our database we have one table having all the routes along with unique ids given for them. Second table comprises of bus stop names with ...
2
votes
0answers
105 views

How to reduce trajectories with Bellman algorithm?

I need an algorithm to reduce trajectories with Bellman algorithm. I haven't found anything searching in Google. Can someone help me? It would be cool have it in MATLAB. Thank you
1
vote
0answers
29 views

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 ...
1
vote
0answers
32 views

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 ...
1
vote
0answers
72 views

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 ...
1
vote
0answers
25 views

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 ...
1
vote
0answers
24 views

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 ...
1
vote
0answers
60 views

Make “qgis:delaunaytriangulation” and “qgis:dissolve” save their outputs on a specific predefined layer

I'm new to python and QGIS. I'm working on modifying a plugin which runs algorithms "qgis:delaunaytriangulation" and "qgis:dissolve" like so delone_triangles = ...
1
vote
0answers
130 views

How to check if a polygon contains another polygon in OL3?

Is there any possibility to check if a polygon is contained in another polygon in OL3? I noticed there is a couple of methods in ol.extent e.g. ol.extent.containsExtent(extent1, extent2). But this ...
1
vote
0answers
289 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 ...
1
vote
0answers
22 views

Getting incorrect results for Geary's Coefficient algorithm (incorrect math?)

I'm not sure if anyone here can help me with this, but I'm currently working on a program that uses a spatial autocorrelation algorithm to analyze patterns in an image. It's supposed to return values ...
1
vote
0answers
41 views

How can I automatically make new computings after I have modified some value in a field in ArcGIS Desktop?

I'm a computer programmer and I have no idea about geographic things. I have got a long algorithm with a lot of computings, computed from a previous computed field. There are 7-8 computed fields and ...
1
vote
0answers
30 views

Buffering/extrusion of a dem surface

I have a surface representing a DEM and i would like to add it some thickness. If i simply duplicate the surface and translate it down by my thickness, i get non uniform thickness, ie thinner where ...
1
vote
0answers
85 views

Calculate distance in point collection algorithm

I've got collection of points which are sorted by x,y and distance between n and n+1 (array of objects [{x:0,y:0},{x:1,y:1}....] I would like to calculate distance between all points (point 1 distance ...
1
vote
0answers
271 views

What steps does SAGA GIS take when calculating Topographic Wetness, specifically when handling depression filled (by ArcMap) DEM

I am a grad student involved with hydrological modeling. In the model I work on, we are calculating the Topographic Index (TI; without transmissivity - or set to 1) using Quinn's MFD algorithm. We do ...
1
vote
0answers
321 views

How to Calculate Geolocation Intersection of Two Vectors?

I'm unfamiliar with much GIS terminology but am tasked with solving a specific geolocation problem. For what it is worth, this is for an iOS project, so the data I can collect for analysis is that ...
1
vote
0answers
55 views

What are problems & biases stemming from mathematics behind using Monte Carlo Markov Chain to make heatmap?

My buddy and I are using Monte Carlo Markov Chains to make a heat map - in the interest of rigour, and out of curiosity: "What are the problems & biases that stem from the mathematics behind ...
1
vote
0answers
136 views

Line defined by two geographical points crossing circle area with defined radius

I'm trying to calculate the amount of lines defined by two geographical points crossing a circle area defined by a center and radius. I've tried to use algorithm discussed here, but in my case it ...
1
vote
0answers
281 views

Divide polygon evenly based on lines and intersection points

I have this purple polygon illustrated in the figure below. I would like to split the polygon so that each line segment (green) split the polygon evenly with the surrounding line segments. A line ...
1
vote
0answers
146 views

Kalmanfilter GNSS IMU

I want to make an uncoupled Kalman filter. The input data are GPS and the output of my strapdown Algorithm from the IMU. The Strapdown Algorithm is used to calculate the actual position and velocity ...
1
vote
0answers
73 views

Indexing GIS data associated with user with timestamp

I have data for each user in this format user1:(timestamp,lattitude,longitude) user1:(timestamp1,lattitude1,longitude1)..... Here the 1 at the end of timestamp/lat/long is to specify a different ...
1
vote
0answers
122 views

An algorithm for locating candidate labelling boxes within a polygon

Has anyone implemented this algorithm In PostGIS? Quoting from the paper: Vector-based geographic information systems usually require annotation, such as a polygon number or attribute data, in a ...
1
vote
0answers
76 views

Allocate places according to distance

I've asked this over on Stack Overflow but thought that someone may have a GI point of view that may help: As an over-simplified example I have a list of events that have a maximum attendance: ...
1
vote
0answers
130 views

How can I assign road names from OSM to gis linestrings using open source tools?

Starting with a shapefile of linestrings I want to assign street names to these lines if there is a match with a road/street in OpenStreetMap. There are no exact matches as the linestrings have a ...
0
votes
0answers
18 views

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 ...
0
votes
0answers
10 views

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 ...
0
votes
0answers
21 views

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 ...
0
votes
0answers
30 views

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 ...
0
votes
0answers
50 views

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 ...