Stack Overflow
Stack Overflow

Questions tagged [gis]

A Geographic Information System (GIS) captures, stores, analyzes, manages, and presents data that are linked to location(s). The GIS Stack Exchange should be considered for questions with this tag.

According to Wikipedia:

A geographic information system (GIS), geographical information system, or geospatial information system is any system that captures, stores, analyzes, manages, and presents data that are linked to location(s). In the simplest terms, GIS is the merging of cartography, statistical analysis, and database technology.

There is a Stack Exchange site devoted to Geographic Information Systems.

6555 questions
15
votes
1 answer

How to calculate the distance in meters between a geographic point and a given polygon?

First of all, I'm new to GIS, so pardon any mistakes. I need to discover the distance between a latitude and longitude point and a latitude/longitude polygon (regular or not). Precisely, I need to discover the minimal distance from a given point to…
Marcos Roriz Junior
  • 4,076
  • 11
  • 51
  • 76
15
votes
1 answer

Difference between multipolygon and polygon in PostGIS

What is the difference between point and multipoint ? linestring and multilinestring ? polygon and multipolygon ? In PostGIS What is the secret behind defining "Multi" shapes?
Ahlam
  • 317
  • 2
  • 3
  • 8
14
votes
3 answers

R/GIS: Find orthogonal distance between a location and nearest line

I am trying to find the orthogonal distance between a set of location coordinates and a set of lines (roads or rivers). The set of points are in the form of latitude/longitude pairs, and the lines are in a shapefile (.shp). Plotting them on a map is…
user702432
  • 11,898
  • 21
  • 55
  • 70
14
votes
1 answer

Scaling marker size with marker icons from a sprite in Google Maps API v3

I'm playing with the Google Maps API (v3) and I've run into an issue with marker icons. I'm trying to vary the size of my markers depending on their individual data attributes. The icons themselves are in a sprite that contains three different…
Maxim Zaslavsky
  • 17,787
  • 30
  • 107
  • 173
14
votes
3 answers

Geographic obstructions in radius searches

I am new here and points poor so I can only offer 50 pt bounty. Suppose I have an application a search for all gas stations within 10 mile radius of a certain location. However one side of this location is surrounded by a mountain range that you…
Michael Papile
  • 6,836
  • 30
  • 30
14
votes
4 answers

How to find which polygon a point belong to via sf

I have a sf object that contains polygon information (precincts) for a metro area, obtained through a .shp file. For a given lat/lon pair, I want to determine which precinct it belongs to. I'm thinking I can utilize sf::st_contains() but am having…
kevinykuo
  • 4,600
  • 5
  • 23
  • 31
14
votes
2 answers

How do I find the polygon nearest to a point in R?

I have a spatial points data frame and a spatial polygons data frame. For example, my polygons would be a polygon for each block in Manhattan. And the points are people, which are scattered all over, sometimes falling in the middle of a street,…
Kiefer
  • 163
  • 2
  • 8
14
votes
2 answers

Dissolve holes in polygon in R

I am running some geoprocessing tasks in R, in which I am trying to create some polygons for clipping rasters of environmental information. I am buffering somewhat complex polygons, and this leaves small subgeometries that I would like to get rid…
Pascal
  • 1,590
  • 2
  • 16
  • 35
14
votes
5 answers

"No Disk" error using GDAL from C#/.NET

I am using Tamas Szekeres builds of GDAL including the C# bindings in a desktop GIS application using C# and .net 4.0 I am including the entire GDAL distribution in a sub-directory of my executable with the following folder structure:…
Blue Toque
  • 1,775
  • 13
  • 24
14
votes
4 answers

See if lat / long falls within a polygon using mysql

I have the created the table below CREATE TABLE geom (g GEOMETRY); and have inserted many rows, example below: INSERT INTO geom (g) VALUES(PolygonFromText('POLYGON(( 9.190586853 45.464518970, 9.190602686 45.463993916, 9.191572471…
Josh Morgan
13
votes
6 answers

Similarity between line strings

I have a number of tracks recorded by a GPS, which more formally can be described as a number of line strings. Now, some of the recorded tracks might be recordings of the same route, but because of inaccurasies in the GPS system, the fact that the…
Liedman
  • 10,099
  • 4
  • 34
  • 36
13
votes
2 answers

Automatic Label Placement for GIS maps in R

I'm making GIS maps in R using the sf package (and related packages) to read in shapefiles, and ggplot2 (and friends) for plotting. This works fine, but I can find no way to (automatically/programmatically) create label placements for features such…
invertdna
  • 171
  • 6
13
votes
3 answers

Algorithm for merging spatially close paths / line segments

I am looking for (the name of) a geometric algorithm for cartographic generalization of a street map. In my map data, I have many paths (ordered list of points, connected by line segments) that lay close and almost parallel to one another. How do I…
anroesti
  • 11,053
  • 3
  • 22
  • 33
13
votes
4 answers

Geo-Search (Distance) in PHP/MySQL (Performance)

I have a MySQL-table (MyISAM) containing about 200k entries of lat/long pairs that I select from, based on the pairs distance (great circle formula) from another lat/long pair. (e.g. all entries that are within a 10km radius around 50.281852,…
Dexter
  • 3,072
  • 5
  • 31
  • 32
13
votes
1 answer

World map showing day and night regions

I'm trying to add a daytime/nighttime line to a world map using ggplot in order to indicate day and night regions; something like this: The plan is to animate my map over a 24 hour cycle like this: The above animation is achieved using a sine…
jogall
  • 651
  • 6
  • 21
1 2 3
…
99 100