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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5
votes
4answers
1k views

Find the best path along raster

I've just posted a question to StackOverflow about the best way to go about finding the best path on the raster below (where whiter pixels are 'better'), but have realised that it might actually be ...
7
votes
3answers
931 views

Retrieve polygon smallest MBR

I have a postgis table containing polygons. I want to transform my polygons to 4 points polygons : retrieve the smallest MBR. Here comes an illustration of what I want : My original polygon is ...
5
votes
2answers
285 views

Algorithm to determine if there are any landlocked polygons

Imagine that I have the need to determine landlocked countries. Is there a to do it automatically? Any known implementations? The target platform on this will be ESRI.
6
votes
2answers
981 views

Transform SPOT5 images to natural color images

We're currently using PixelSense to convert raw SPOT5 images to natural color ones for display and printing. Do you know a good algorithm to perform the same task as we want to ingest raw images in an ...
0
votes
0answers
646 views

buildings shadow areas calculation

is it possible to calculate shadow areas of buildings or simulate shadows of buildings in a city using e-cognition software, with the DSM of the buildings and the sun angle and azimuth known?....if ...
4
votes
6answers
3k views

shadow simulation from buildings [duplicate]

is it possible to use hillshade function in ArcMap to calculate shadow areas of buildings or simulate shadows of buildings, using DSM of the buildings and the sun angle and azimuth?
17
votes
3answers
4k views

Find tunnel 'center line'?

I have some map files consisting of 'polylines' (each line is just a list of vertices) representing tunnels, and I want to try and find the tunnel 'center line' (shown, roughly, in red below). I've ...
3
votes
1answer
295 views

How can a single line be computed from multiple possibilities

I have datasets containing continuous GPS streams of data that represent routes or trails. For any given route, I probably have at least 5 (in some cases many more) different sets of data. Given that ...
11
votes
9answers
8k views

Algorithm for finding irrregular polygon centroid (label point)

I need to find a centroid (or label point) for irregularly shaped polygons in Google Maps. I'm showing InfoWindows for parcels and need a place to anchor the the InfoWindow that is guaranteed to be on ...
4
votes
3answers
3k views

Parameters for ED50 -> ETRS89/WGS84 seven-parameter transformation which are good for Denmark?

I am looking for parameters for a seven-parameter transformation (Rx, Ry, Rz, Tx, Ty, Tz, s) from ED50 UTM (zone 32U) to ETRS89 and/or WGS84. The best match I could find is here: ...
10
votes
2answers
386 views

Tools for importing historical maps into modern GIS systems

What tools exist to derive geometries for use with modern GIS systems from older scanned maps? I am referring more to libraries that generate actual data rather than present an interface for manually ...
2
votes
1answer
367 views

How do I calculate curvature using GIS co-ordinates [closed]

I have GIS data for which I would like to calculate where curvature is present. Anyone has done this before, please help.
72
votes
14answers
23k views

What are Definition, Algorithms and Practical Solutions for Concave Hull?

Convex Hull A convex hull of a shape is defined as: In mathematics, the convex hull or convex envelope for a set of points X in a real vector space V is the minimal convex set containing X ...
10
votes
4answers
768 views

Point Pattern Analysis Algorithms

I'm looking for point pattern analysis algorithms and literature on point pattern analysis, online resources and book titles welcome. The topics may range from general descriptions of algorithms to ...