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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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? ...
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1answer
17 views

Geoserver (automatic labeling generalization)

I am a Master student looking to do my thesis in cartographic labelling using GeoServer. The thesis topic will be something like "Cartographic Labelling in Real Time Mapping using Web Services. I am ...
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19 views

Where to find more detail on algorithms used in ArcGIS Desktop's location allocation solver?

Where can I find more detail on the algorithms used in ArcGIS Desktop 10.0's location allocation solver? The help file specifies the following: The location-allocation solver starts by generating ...
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1answer
30 views

Determine when heading off course

How does google or other map providers with routing capabilities determine when you are not staying at the right course? I am trying to figure out how to implement this feature in my gps that I am ...
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15 views

Algorithm to scan a road network geometry using directions service

Let's suppose there's a Directions Service which, given a pair of points, returns the geometry, along the network, which best connects those points (which are previously projected - "snapped" - to the ...
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15 views

Is there a Minimum Cut Network Delineation Package in QGIS?

Currently I am working out how to best subdivide a pipe network into respective areas. One of the best ways to delineate this network is to subdivide the region into strongly connected areas such that ...
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1answer
49 views

Cover a polygon with fixed size squares

Can you please advice me of an algorithm (which I can implement in a Java) to cover some polygon (not exact cover) with squares of certain size (aXa squares)? The cover doesn't have to be exact - ...
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1answer
57 views

How to find if two gps tracks were from the same trip?

Given I have gps tracks from many users running or hiking, how can I find out who were running together? In other words, which algorithms are there to find out who were in the same party? Haven't ...
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1answer
27 views

Is this Intersect or Union algorithm associative?

Similar to Is the Intersection Operation Commutative? . Spoiler for that one: Intersection is commutative and associative. I've created an algorithm (in PostGIS but the theory would work in other ...
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2answers
115 views

Best flow routing algorithm for determining location where spill enters stream?

What would be the best flow routing algorithm for determining the quickest (and by this I suppose I mean shortest) path that a spill would take when traveling to a stream? My best educated guess ...
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48 views

Available modules/products for GPS+IMU sensors shipped with sensor fusion SW?

Are there any solutions/products (modules) in the market that integrate GPS and IMU sensors that come together with the sensor fusion algorithms (Kalman filtering etc.) implemented and ready for use? ...
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65 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 ...
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24 views

A Distributed Cost-Distance Algorithm

I'm currently trying to implement a distributed cost-distance algorithm, however I can't seem to invent my own and still make it fast. I've been googling around a bit but haven't found anything that ...
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1answer
44 views

netCDF4 Python climate algorithm

I have been working in Python with the Acaconda Python distribution to create code that accomplishes the following algorithm: I have multiple variable netCDF4 files [NCEP Reanalysis tmax(K), tmin(K), ...
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10 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 ...
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0answers
28 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 ...
2
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1answer
40 views

J2000 to WGS84 in QGIS?

How to transform Earth-Centered Inertial J2000 CRS to WGS84 CRS in QGIS? I searched J2000 in spatialreference.org, however nothing found. I don't know the proj4 string of J2000. Any advice would be ...
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2answers
64 views

Is there an algorithm for transforming from CGCS2000 to WGS84?

Is there an algorithm that supports transforming from CGCS2000 coordinate to WGS84 coordinate? CGCS2000 is China Geodetic Coordinate System 2000. Any advice would be thankful!
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1answer
40 views

How to assess quality of the TSP algorithm?

I'm trying to develop my own algorithm for solving Travelling Salesman Problem (TSP) I tested it (in its current state) on the "att48" instance of the TSPLIB and got following results: As we can ...
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1answer
53 views

Aggregating river basins

I am not a hydrologist but am providing GIS infrastructure to our hydrology department which actually doesn't use GIS very much yet. Therefore I am asking for some hydrology related insights. Btw: We ...
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1answer
52 views

Which algorithm does gdal_polygonize use?

I would like to know which algorithm (i.e. Sobel operator ) is used to extract the polygons in gdal_polygonizer. I searched here and here but could not find it. Any help would be appreciated.
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50 views

Algorithm to find the boundary grid points [duplicate]

Let us consider a set S consisting of a collection of grid locations (i,j),i,j=1,\ldots,n, in 2-dimensional gridded plane. Here the point (i,j) corresponds to a rectangular grid in the X-Y plane. ...
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26 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. ...
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69 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 ...
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0answers
36 views

How to find the the boundary co-ordinates from a given set of coordiantes? [duplicate]

How to find the the boundary co-ordinates from a given set of co-ordiantes? I understand that this question asked previously and answered here How to find the boundary co-ordinates from a given set ...
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1answer
87 views

Fast raster combine using rasterio

I'm trying to duplicate the functionality of ArcGIS's Combine function within rasterio. Given a list of (presumably categorical) rasters read with rasterio, I want to output a combined raster and a ...
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22 views

Tools to generate all the possible geometries meeting specific constraints

I have an area = 2d polygon (generally a 4-side shape). I would like to generate all the possible rectangles matching the following constraints: that fall within the surface of the area with a ...
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2answers
440 views

How do the equations/algorithms behind buffering tools actually work?

I've been wondering how the equations/algorithms behind buffering tools actually work?
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3answers
178 views

Buffer Zone Algorithm

I use google maps, php, mysql, and I want to create a buffer zone in line among some points. Could someone tell me where can i find the algorithm (php library or the math in order to implement it) to ...
2
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0answers
249 views

How to calculate grid convergence (True North to Grid North)?

I would like to know how to calculate the grid convergence angle between True North and Grid North for UTM maps. I am using ArcGIS 10.0 (ArcView licence) and have used the Calculate Grid ...
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22 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 ...
2
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1answer
49 views

Find a path between an origin and destination given scattered points

We have a postgis database containing a lot of ordered (by date/time) nautical point (lat/long). Each of these points are affected to a leg between an origin and a destination (both origin and ...
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20 views

PRN (p-code) to Geocode Conversion

I think I have a unique situation. Client has a file containing the old p-code / PRN but can't relate this to a specific address and desires to move to a geocode orientation. Does anyone know if a ...
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1answer
34 views

Locating Moon in Sky from Earth

I am working on project which need to find moon location from a specified lat, long on earth. So basically info I am having is Lat,Long and Timezone. Format of the moon location Info? So first in ...
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3answers
161 views

Interpolate data from multiple gpx tracks

I have a number of GPX tracks of the same road. But due to GPS error they are not accurate enough (20-30m off). I'm wondering if I could interpolate those multiple gpx tracks into single one. If an ...
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1answer
400 views

How to get Intersection point from two lines (coordinates)

I have tried for ages to find the algorithm for getting the coordinate of two intersecting lines from a given coordinate (latlong). As the picture below suggest. I have two coordinates (A and B). ...
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1answer
70 views

Calculating the fastest routes and some points on the same time

I have two drivers and each driver has a set of about 15 locations where they need to drive to on a single day. Calculating the shortest route for both drivers is not the problem (using a matrix ...
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30 views

How do I map points on a 2D map to a 3D illustration of the same area? [duplicate]

I'm looking for advice on how to build an algorithm that maps any point on a map to a point on another map, interpolating where needed. Let me better clarify with an example of what I concretely ...
4
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1answer
75 views

What are definitions of watershed segmentation, local maxima, variable window search, regarding LiDAR for vegetation?

I am not familiar about Lidar. I want to measure trees height and number of trees. I guess, watershed = to locate the trees, local maxima = to measure trees height. I used these methods in SAGA GIS. ...
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1answer
184 views

D8 algorithm to get the flow direction in ArcGIS

I am using ArcGIS 10 for the get the flow direction from DEM. I wonder about the algorithm they have used while calculating flow direction. It is mentioned there that it is using D8 model. D8 model ...
4
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1answer
178 views

What is an efficient Algorithm to draw a straight line from points?

I have some cross section survey data, which is like this: X Y Z pt_dt 2970969.635 359725.0088 83.4242 1-x 2970968.278 359722.2182 83.2591 1-x 2970941.771 359670.127 83.0655 1-x 2970961.369 ...
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3answers
135 views

Is it possible to create a standalone model in ArcMap Modelbuilder?

Is it possible to create an algorithm in ArcMap Modelbuilder that could then become a fully standalone applet? I would like to be able to provide this processing algorithm even to users who do not own ...
3
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2answers
81 views

Step by step contour creation algorithm

I do seismic processing, and recently have been moving into doing contours. I have a question on the exact way this is done. I have watered down my problem so that I can understand from 'first ...
6
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1answer
527 views

Advantages of R-trees in comparison to geohashes

Geohashes are being widely used in products like: Lucene, mongodb, etc and have become one of the most important technology of present day. Have Geohashes replaced the good old R-trees or do R-trees ...
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1answer
107 views

Algorithm to find geohashes which satisfy query condition

I have an application where I need to query geohashes by specifying the bounding rectangle. Since geohashes map 2D to 1D is there a method by which I may find the prefixes of all geohashes which ...
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0answers
41 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 ...
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1answer
57 views

Counting number of points in 1 km grid covering surface of Earth?

I want to cover surface of earth with equal sized shapes and count number of points within each cell. shape of cell doesn't matters (triangle, hexagon ...), neither area, but equality of them is ...
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1answer
58 views

How can I find a Douglas-Peucker algorithm for simplification? [duplicate]

I want to understand simplification methods in GIS. I searched the Internet and found that the best simplification method is the Douglas-Peucker algorithm. I could not find any information about the ...
4
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1answer
186 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 ...
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1answer
137 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 ...