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

learn more… | top users | synonyms (1)

3
votes
1answer
99 views

Placename matching algorithms and services for geocoding

Are there any placename-specific matching algorithms, routines or services available? By placename specific I mean not just a simple string-difference match, or soundex/metaphone, but something that ...
3
votes
1answer
81 views

Find gap in / endpoints of linestring

I have a set of features of type linestring. I'm trying to polygonise the linestrings and assumed that they were closed (naive me :) ). Of course some were not closed and I'm trying to locate the gaps ...
0
votes
1answer
64 views

Determining if a Geodetic location is inside a polygon made up of Geodetic vertices

Suppose we have a polygon with Geotic vertices (Points A through E). Is there an algorithm that I can use that could determine If F is inside of it? In addition, what is the most efficient way to ...
-1
votes
1answer
84 views

How to find the most east or west longitude around the date line

I've got a python script that is comparing extents of rasters in various projections. Generally it works, but sometimes, especially when the rasters are global in extent or cross the dateline it ...
4
votes
0answers
196 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 ...
4
votes
0answers
226 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 ...
3
votes
0answers
39 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
189 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
40 views

Topographic Index - Why is upslope contributing area divided by downslope contour width and not upslope contour width?

In the Topographic Index calculation, a is the upslope contributing area per unit contour length. Is the "unit contour length" calculated from examining the contour widths of the downslope cells that ...
2
votes
0answers
52 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
39 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
44 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
104 views

Find and destroy duplicate OSM multipolygon/polygons in TileMill/PostGIS

In OpenStreetMap there are sometimes multipolygons where attributes are present on both the polygon and the multipolygon relation, such as the Grampians National Park: ...
2
votes
0answers
154 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
126 views

oil palm stand census algorithm

Anyone have experience in oil palm stand census using tree detection algorithm from satellite images in ArcGIS or QGIS? any references for usable algorithm? What is the accuracy? thanks for help.
2
votes
0answers
116 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
717 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
75 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
17 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
81 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
65 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
38 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
78 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
166 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
89 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
46 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
82 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
69 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
87 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 ...
1
vote
0answers
272 views

Algorithm to place the minimum of rectangles to cover a polygon

I'm trying to cover a polygon with the minimum set of rectangles like explained in the picture below, the used rectangles have the same size a*b (a != b) , the rectangle could be rotated by ...
0
votes
0answers
40 views

Error: Algorithm not found

I wrote the following code to start using QGIS APIs. in a very short script seen below, the "Error: Algorithm not found" is thrown and "print processing.alglist()" is showing none. Any idea why this ...
0
votes
0answers
20 views

'QgsGraph' object does not support indexing

Traceback (most recent call last): File "/home/kasun/.qgis2/python/plugins/floogin/floogin.py", line 246, in findRoutes path=self.astar.astarSearch(graph, start, end) File ...
0
votes
0answers
12 views

Convert ECF to Suface ECF

I'm using the 3D Earth WorldWind Model and I have a path that I want my object to travel. I set the the destination and interpolate to the end point from my current location. The problem is using ECF ...
0
votes
0answers
68 views

Algorithm to find coordinates at selected intervals along a polyline?

I am developing an algorithm to search down a river at selected intervals and return the coordinates. See below: def Downstream(start, interval, data, offset=0, out=None): if out is None: ...
0
votes
0answers
34 views

return to newline arcgis/arcSDE/postgres labeling

i have two tables : parcel and owners with many to many relation ship so i want to print owners name in my parcels (type polygon), so i coded using .net a function that create field in parcel ...
0
votes
0answers
73 views

Route through water polygons

I have a water-polygon grid shape file as shown (Each grid is 1latx1long): I have created this in QGIS and files (coastal lines and land polygons) selected from http://openstreetmapdata.com/data ...