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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10
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1answer
581 views

How to visualize azimuthal data with uncertainties?

I am trying to make a figure showing azimuthal data with a different range of uncertainties at each point. This oldschool figure from a 1991 paper captures the "bowtie plot" idea that I'm aiming for: ...
5
votes
1answer
605 views

Polar grids in ArcGIS

I am looking automate the creation of a polar grid shapefile (polygon). I am currently creating this in a many-step editing process, starting from a concentric buffer. Here is how I think I should be ...
3
votes
1answer
247 views

how to implement genetic algorithm in ArcGIS?

I want to implement genetic algorithm to find optimum location for placement problem with ArcGIS. Can any body explain it (step by step ) or any resources about that ?
9
votes
4answers
2k views

How to filter wrong GPS points?

I have a database of GPS points. There aren't any tracks, only points. I need to calculate some value for every 100 meters, but sometimes GPS gave a wrong coordinates that lies far from real GPS ...
8
votes
3answers
407 views

Find Duplicate Polygons Algorithm

I have a group of polygons. My objective is to find the duplicate polygons from these group of polygons. Using NetTopologySuite(A c# port of JTS), it is possible to compare two geometires and check ...
4
votes
1answer
311 views

How To Calculate Height of Point B?

I have a survey point data which has coordinates X,Y, Height, Angle(Dip),Azimuth, and Depth(Distance). for Example, point A: Easting: 290694 Northing: 715927 Elevation: 1060 Angle: 65° ...
3
votes
2answers
3k views

How to split a line at point positions?

I am a rooky with QGIS and i am stuck from a basic problems. I have a polyline and i have some points (2) on the polyline. I would like to know if there is a tool or script that i could use to ...
10
votes
1answer
346 views

Are there any intelligent travelling salesmen?

Jokes aside, I have had a routing problem that is almost a travelling salesman problem (TSP): the starting point is defined the end point coincides with the starting point each node has to be ...
14
votes
1answer
163 views

Alternative indexing methods for point set operations

It is common to use a bounding box spatial index to improve performance when working with a large number of features. Where operations are performed against individual geometries with a large number ...
4
votes
1answer
229 views

Given a known batch of mobile-obtained gps data with timestamps, what algorithms can be used to clean it?

I'm working on the backend for an iOS/Android app that collects locations every hour and syncs with the server every three hours. The mobile apps themselves are not under my control and so I can't ...
4
votes
2answers
973 views

How to calculate area of 1 x 1 degree cells in a raster

I have a simple array (not geo-referenced in any way) in Matlab (which is not a language I know a huge amount about...so I can export it to other languages if needed) which has the dimensions 180 x ...
8
votes
1answer
830 views

Given a line on the earth's surface, how do I plot a line perpendicular to it?

Given a line on the earth's surface, how do I plot a line perpendicular to it? Apologies if this is a very simple question. I thought this would be a straightforward task, but it is proving ...
6
votes
2answers
411 views

how to find the point in a country furthest from a boundary

i'm trying to find the point in south africa furthest from the sea or a landward boundary. my method thus far: i obtained a first guess at the centre of the inscribed circle and the three segments ...
4
votes
2answers
7k views

Calculate bearing between two decimal GPS coordinates

I'm building a virtual tour application that uses custom panoramas in conjunction with Google's StreetView service. With StreetView, you can have 1 to n links at each particular location to move to, ...
8
votes
1answer
1k views

Computational most efficient way to convert Cartesian to Geodetic Coordinates

As far as I understand the literature there are several ways to convert a set of geoecentric cartesian coordinates to geodetic coordinates Bowring, 1976 Borkowski, 1989 Lin & Wang, 1995 Toms, ...
6
votes
1answer
428 views

How to calculate the bearing of a building (ArcGIS)

How is it possible to get the main bearing of buildings by floor plan? I want to have a building (by ID) and it's main bearing (e.g. E/90° or W/270°). The idea is to change the polygon-feature class ...
12
votes
4answers
600 views

Dikes extraction from DEM

I do have DEM of 1x1 meter and original LiDAR point cloud in .las, that DEM is made of. I need to extract river dikes (highest points of the dikes) to vector feature (point, polyline). Any idea for ...
1
vote
1answer
108 views

Algorithm to find distance of an uneven polygonal road

While working for my summer internship I have got a task to implement an algorithm to find the crosssecting points of two roads or more and then place that cross-section point a number and then find ...
3
votes
2answers
2k views

How to find a point on given line that its distance from another point is given also?

I have this input: (lat1,lon1), (lat2,lon2) - Two coordinates that create the line (lat0, lat0) - Point on this line d - distance I want to find a point (lat, lon), where (lat, lon) is on the ...
2
votes
3answers
287 views

Get the LatLon of middle points of a road segment?

Suppose I have the LatLon of the two end points as well as a small number of middle points of a road segment. What is the best way to calculate the LatLon of a middle point P of the road segment ...
7
votes
1answer
1k views

Grouping map points into fixed cluster sizes

I have a dataset of 655 lat/long pairs which I'd like to split into about 100 groups. A group should have 5-10 pairs which are geographically close to each other. Dense groups should have more ...
3
votes
1answer
554 views

Why are the results from the same data different in ArcGIS vs MS Excel?

I have done some interpolation in Geostatistical Analyst in ArcGIS and I got the Standard Deviation (SD) a bit different from the SD that I calculated in Excel Spreadsheet. What algorithm does each ...
2
votes
3answers
590 views

Split polygon with holes to get several hole-less polygons

Unlike this thread I actually need to split the polygons into several hole-less polygons. I'm not sure on how to approach to this problem. I have polygons with holes of many diferent shapes, like ...
6
votes
3answers
4k views

Splitting lines automatically at specific distances using ArcGIS Desktop?

I have a set of polylines which I need to split at varying distances from their starting points. In general, I'm looking for a something similar to the SPLIT function within the editor tool. There ...
5
votes
2answers
267 views

Raster calculation confusion

I need to do some raster calculation, I've been trying to make it work but I am not sure everything is working properly. I need to apply a formula, but I am unsure if I am doing it properly. The ...
16
votes
1answer
1k views

Robust alternatives to Moran's I

Moran’s I, a measure of spatial autocorrelation, is not a particularly robust statistic (it can be sensitive to skewed distributions of the spatial data attributes). What are some more robust ...
2
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0answers
61 views

Computational time of well-known compression algorithm [closed]

I have googled for get information about computational time of some compression algorithms but information seems contradict each other. I need worst case performance of the following algorithm Sliding ...
10
votes
1answer
271 views

Looking for a trajectory similarity measure

For my final academic work I have developed a compression algorithm for GPS trajectories. I can estimate the quality of the spatio-temporal compression by computing the syncronized euclidean distance ...
2
votes
0answers
78 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
2
votes
0answers
119 views

Any Open source implementation just like ArcGIS Desktop Identity function? [closed]

I tried to identity thousands of points with millions polygon. ArcInfo work well but i have to get the result from Web Services.So i tried to implement the algorithm(Point in polygon) by myself,it ...
6
votes
1answer
581 views

Breakline detection algorithms for LIDAR dataset

I'm searching for algorithms or open source tools I could use to detect breaklines from a LIDAR dataset; more specifically, from the terrain points of the dataset. At the moment the only thing I've ...
3
votes
0answers
203 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 ...
6
votes
1answer
599 views

How do I find least cost path over a DEM based on slope magnitude and direction?

What sort of algorithms can I use to find a least cost path through a DEM where it costs more to traverse a cell going downhill or uphill than it does to follow the contour of the land? All the ...
3
votes
0answers
261 views

How to get all intersections between two simple polygons in O(n+k)? [closed]

Can someone help with a following problem: report all intersections between two simple polygons in O(n+k) where n - is a total number of polygon edges and k - is number of intersections. As a result - ...
3
votes
1answer
1k views

WGS point to WGS line segment (great circle) distance

How would I go about resolving this in C#? I have a line segment (great circle distance) defined by two Lon-Lat pairs (call them points A and B). A third point somewhere on the Earth sphere. The ...
27
votes
4answers
7k views

How to find the minimum-area-rectangle for given points?

The following is another problem that I am working on it these days. As you see in the figure, (BTW, I tried to make it self-presenter) the question is: How to find the minimum-area-rectangle (MAR) ...
29
votes
1answer
8k views

How to find the center of geometry of an object?

Well it might be a simple question. Given a set of 2D or 3D points, the question is: How to find the center of geometry of an object? According to the following figure, the center of geometry ...
6
votes
1answer
371 views

How to find the smallest-area ellipse circumscribing a convex polygon?

We are currently dealing with the problem of: How to find an ellipse circumscribing a convex polygon? Recent googling and lots of reading could not help me so much :(
3
votes
1answer
420 views

How Can I Calculate Time from Coordinate?

For my application I am searching for an API or an algorithm for clicking point time and time zone. I dont know how I can do this but after getting time I want to calculate giving coordinate sun ...
5
votes
1answer
224 views

algorithm for displaying holes in a polygon by translating it into several hole-less polygons?

I'd like to plot polygons with holes on a framework that doesn't support holes. The approach to me seems to be to translate the single polygon into several ones adding up to the whole polygon, leaving ...
3
votes
2answers
245 views

Need an explanation on a network simplification algorithm

I try to implement the algorithm described in this paper (page 8), but there's a place that I can't understand, and the authors do not provide a more detailed explanation or pseudocode. They show how ...
3
votes
2answers
915 views

Finding the minimum and maximum distance between an observer and a lat/lon bounding box

I have three points in geographic coordinates (latitude, longitude, altitude). One of the points represents an observer, above the Earth. The other two points define a bounding box. I'd like a ...
2
votes
1answer
2k views

How to get the radius of a “circle” in Openlayers

How do you get the radius of a circle in openlayers? I have searched quite a bit and cannot find any resource for this. please help. Here is my code but I want the radius or circumference of the ...
2
votes
1answer
219 views

Is there any simple Map Labeling Algorithm?

I was looking into how to Label a few features on a small Map, and want to label them on the fly. I would be adding a few features (a maximum of around 6 to 7) as graphics on a web-Map which has ...
3
votes
1answer
883 views

Point of Intersection for a Ray and Earth's Surface

Say I have a ray vector originating from somewhere out in space. An example might be a ray of light from the sun. How can I calculate the point of intersection (if it exists) between the ray and the ...
7
votes
2answers
2k views

What algorithm should I use to remove outliers in trace data?

I have GPX traces and want to remove outlying observations. There are some route points that are impossible because it would require acceleration that the vehicle can not achieve. Are there good ...
1
vote
4answers
256 views

Looking for compute intensive GIS vector operations

I am looking to make efficient algorithms for those vector GIS operation that take a long time for GIS software like Arc-GIS, Grass etc. I have considered polygon overlay but looking for other ...
1
vote
1answer
500 views

How to speed up batch watershed delineation?

Hi this is probably a longer-winded question than it needs to be, but please bear with me. I have a large number of pour points - approximately 250,000 for which I want to delineate the upstream ...
7
votes
2answers
225 views

How to handle interpolation of multiple (quality) tiers of irregular data?

I'm going to try to provide a high level overview of the issue - realizing that more details/info will be necessary - but I don't want to write a novel that seems too overwhelming for people to ...
2
votes
2answers
227 views

How to remove roads from dataset

I've got a shape file that I loaded into PostGIS that has both road and parcel multipolygons and I need to remove the roads. I tried loading the shp file in qgis and it loads them both as a single ...