A coordinate-based data model that represents geographic features as points, lines, and polygons.

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46
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6answers
1k views

Are there any attempts to replace the shapefile?

Recently I've been spending a lot of time converting perfectly good field names like "Percent of citizens age 25 and over with a bachelor's degree or higher" into things like "edbchogtr" to meet the ...
41
votes
8answers
7k views

How to create Vector Polygons at the same amazing speeds GISCloud is able to render them?

EDIT (outlining new bounty added): I have added the largest bounty possible to this question in hope of getting a very detailed answer. Your solution should outline a step-by-step guide utilizing open ...
25
votes
5answers
39k views

What are Raster and Vector data in GIS and when to use?

What are raster and vector data in the GIS context? In general terms what applications, processes, or analysis are each suited for? (And not suited for!) In answering someone's question today, I ...
19
votes
3answers
512 views

How can we protect GIS data?

I have found a very interesting paper here related to this topic. I just want to have views/ideas from other professional about how we can protect GIS data using Cryptography or Digital Watermarking? ...
17
votes
3answers
13k views

How to clip a raster with vector boundaries?

I am using QGIS. I would like to clip a raster precipitation layer using an admin boundary layer that is vector data. However the geoprocessing tools seem to be usable only for vector data. How can ...
14
votes
7answers
5k views

Nearest neighbor between a point layer and a line layer

I've asked this question several times on stackoverflow and irc between #qgis and #postgis and I also tried to code it or implement it my self in postgis with no real answer. Using programming (most ...
14
votes
3answers
5k views

How do I load OSM vector data in QGIS 2.x?

In QGIS 1.8 I used the openstreetmap plugin to request data from the server, or open a .osm XML file, which produced 3 layers (polygons, polylines and points) in QGIS. This was great (give or take the ...
14
votes
2answers
316 views

Toward a protocol for encoding vector data as image

This is a follow up to this question: How to create Vector Polygons at the same amazing speeds GISCloud is able to render them? In his answer, Yagi outlines a rationale for encoding geographic ...
14
votes
3answers
1k views

Rubber sheeting in GRASS or QGIS

We are in the process of getting our property boundaries corrected and a side effect of this is that we need to move any assets that have been drawn relative to the property boundaries, so they are ...
13
votes
2answers
379 views

Is there any open-source object-oriented GIS?

Most GIS are layer based. But I am looking for open-source object-oriented GIS. Is there any out there? By object-oriented I mean logical data model for vector GIS. Here's explanation of my ...
11
votes
1answer
13k views

Programmatically creating a vector feature in OpenLayers

I want to create a vector feature, programmatically, on my map. It's supposed to be in the A4-paperformat, for showing a sort of print preview. I've created a control for handling this, but now I'm ...
11
votes
4answers
400 views

How to generalize coastlines?

I have a large set of data points that essentially represent the coastline of the world. I don't know the exact resolution but I'd say it's in the neighbourhood of 5-10m. Imagine a set of points ...
11
votes
2answers
1k views

Tiling Vector data without losing geometrical and topological information

I am trying to figure out a way to sub-divide a vector based map into smaller blocks. I can tile the map based on different strategies such as q-tree. However, it is unavoidable to cut some polylines ...
11
votes
3answers
3k views

Convert GeoPDF to a vector format

I want to convert a GeoPDF that has vectors entity in it to a vector format and preserve the real coordinates of these vectors. The GeoPDF has been exported from ArcMap and has layers in it. I have ...
10
votes
5answers
3k views

Libraries to render vector-based maps in the browser

Is there a open source JavaScript library like leaflet or openlayer which can be used in a web or mobile application and loads vector-based maps instead of images? I only need the road information and ...
10
votes
1answer
1k views

How to access feature classes in file geodatabases with Python and GDAL?

I am trying to access a vector dataset in a ESRI File Geodatabase using Python + GDAL. I have successfully compiled GDAL with the file geodatabase API. The FileGDB driver is working correctly since ...
10
votes
2answers
4k views

How to Import SVG into GIS?

I have a PDF file, with a Map as a vector graphic. I want to get this into GIS. (I use ESRI's ArcGIS, but any FOSS solution is also fine). I know that it is not possible to directly get the PDF into ...
10
votes
1answer
392 views

Spatial operators in R?

How can I do spatial selections or filters in R? I can do this in PostGIS using (e.g.): SELECT * FROM mypoint, mypoly WHERE ST_Within(mypoint.geom, mypoly.geom); and it is similarly a piece of cake ...
10
votes
3answers
2k views

How to find and merge duplicate points?

I have two point shapefiles: Red and Blue. Each point shapefile has a z value which represents a radius (i.e. represented as buffers in the example). A duplicate point is defined as a point that ...
10
votes
2answers
508 views

How do I describe a special relationship between connected edges?

Consider this simple situation where three edges connect at a node: I’d like to write a succinct and clear description of the relationship between A and B in such a way that differentiates it from ...
9
votes
3answers
438 views

In what coordinate systems do true circles appear round?

Please excuse what is probably an obvious question from a relative newB to GIS -- this seems like it should be a snap. I've been developing in Gmaps for awhile and am switching to OpenLayers but am ...
9
votes
2answers
904 views

What's the best way to display thousands of polygons in Openlayers?

I am trying to create an Openlayers map that will display thousands of polygons. And when the user clicks on each, I want some of the metadata to display. Working with this large of a dataset seems ...
9
votes
1answer
325 views

What is the best way to represent bridges using a point vector layer in QGIS?

I'm working on a hiking/biking maps of trails in the woods which sometimes have bridges that need to be shown on the map. I'm trying to figure out the best way to capture and represent them using QGIS ...
8
votes
5answers
3k views

How to georeference a vector layer with control points?

I have a non-georeferenced vector layer that I need to be georeferenced. With raster layers the task is easy and straightforward, but I have no idea what should I do with my vector layer. I have a few ...
8
votes
3answers
7k views

Extract Raster Value into Polygon Attribute

I have Raster Data for a State which has Elevation Data in its pixels. I also have Vector layer which has the 300 divisions of State. what I need is, I want to get the average elevation value of ...
8
votes
2answers
681 views

How to convert a vector boundary to a raster map?

I need to output a PNG file of a raster map overlayed with boundaries present in a vector map. The problem is, the r.out.png script only exports a raster map. My boundaries are in a vector format. ...
8
votes
0answers
370 views

SEXTANTE toolbox - GRASS error

I am trying to use the SEXTANTE module GRASS (and SAGA) for vector analysis but whatever function I use I always get the same error:"Could not load layer: G:/closest.shp Check the SEXTANTE log to look ...
7
votes
4answers
2k views

How to identify and eliminate overlaying polygons in Quantum GIS?

I have a shapefile with polygons and now, not sure why, most of the polygons became duplicated and overlaid, i.e. when i click to selected one, i get two selected... How do i identify those polygons ...
7
votes
3answers
579 views

How to get a list of adjacent lots to a road in ArcMAP and PostGIS/QGIS?

In the following map, I have: A line / road layer A parcel / lot layer The Task: Find and count the list of lots adjacent to the road with their types (parcel_type is a field in the parcel ...
7
votes
4answers
460 views

Comparing 2 vector files

I'm looking for a tool which compares two vector files (eg shapefiles). Eg 2 versions of a river network. Quite a lot of the records are equal, but some are different. A possible output would be eg a ...
7
votes
3answers
2k views

How to create a new Spatialite database in QGIS

I've been trying to create a new spatialite database within QGIS 1.8 (SpatiaLite Version 3.0.1; QSpatialite 6.0.3) and keep getting this error: "The SQL query seems to be invalid. no such table: ...
7
votes
3answers
7k views

converting kml into a vector graphic… and back

Is there a simple means to convert, say, an svg or other vector image format file to KML and vise versa? There are incredibly powerful vector editing tools which attempt to replicate the way reality ...
7
votes
3answers
9k views

How to convert a vector layer to raster?

In qgis in the raster menu there is an item "convert vector to raster". This behaves strangely - I do not understand how it is supposed to work. I can select a vector file, an attribute and an ...
7
votes
2answers
154 views

Hashing functions for GIS data

I would like to take geometries from a vector dataset and reduce them to a hash. This hash would then be used to verify the integrity of that data and also identify identical geometries. Do any ...
7
votes
1answer
4k views

How can I merge adjacent polygons in a shapefile that have been split at tile boundaries?

I'm currently using building data from the Ordnance Survey Vectormap District and I've noticed that a lot of building polygons are split in 2 because of the way the OS split up the shapefile. This is ...
7
votes
1answer
179 views

Finding largest number of observations within a given radius

I have the following problem: Given the location of insured properties (say houses with fire insurance), i have to find the largest sum of insured values which fit into a 300m radius. Now, my first ...
7
votes
2answers
221 views

How to remove long linear strips from polygons?

I have a polygon layer representing impervious land cover. This was taken from a land cover raster dataset. The impervious data represents all impervious surface that is not buildings or roads. I ...
7
votes
2answers
449 views

OpenLayers how to maintain layer ordering while using SelectFeature control

I'd like my map to display a few layers in a particular order. Some of these layers are Vectors, others are XYZs, and some of my Vector layers display attribution. Initial layer ordering works fine ...
6
votes
3answers
1k views

30,000 data points… can this be reasonably served using openlayers?

I'm trying to tackle a web GIS problem and need to figure out the best strategy. I have a map with 30,000 cells on it forming a grid for the province of Alberta. I have a list of data points for ...
6
votes
1answer
367 views

Where can I find European City boundary data?

Does anyone know any sources for free European city boundary data? Thanks!
6
votes
1answer
3k views

Openlayers wfs vector layer

I'm trying to add a vector layer with a wfs layer and it's not working.Can anyone point a solution? Openlayers code: var wfs = new OpenLayers.Layer.Vector( "Stavros Features", ...
6
votes
2answers
988 views

Does an openlayers vector layer work across browsers?

I was under the impression that it was. Here is my example: <html lang='en'> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> ...
6
votes
2answers
268 views

Convert points to lines with Python GDAL

I have a dictionary with points. The points are derived from a raster (see image below). The points are not sorted and are not in order. The dictionary looks for example like this: pointDict = {0: ...
6
votes
1answer
845 views

Where can I find a Unesco World Heritage List as boundaries?

I was wondering if anyone knows where to find the UNESCO world heritage list with boundaries? I can extract point data from the json feed for the map on the website http://whc.unesco.org/en/list via ...
6
votes
1answer
3k views

How to create a point along a line given distance

I have been given a non-spatial database which contains the names of lines which I have a shapefile for. The database also has names of points and the distance of each point from the origin along the ...
6
votes
3answers
4k views

Find the nearest raster cell value based on a vector point

I have two layers in ArcGIS: One is a vector point and the other is a raster layer. I want to append the value of the raster data grid to the vector point. The problem is the vector point is away from ...
6
votes
1answer
183 views

Creating an “average” polygon

I found this thread in the old ESRI forums with the same type of problem I am facing today. The solution to the problem is explained in little detail and since I am not an expert, I was wondering if ...
6
votes
1answer
178 views

Fast data representation on the vector layers

I have found an interesting article about how HTML5 supports representation on large datasets. Article can be found here. In the article it is said that HTML5 and feature simplification can ...
6
votes
1answer
389 views

How to use simplify()

i have my Vector Data saved in a PostgreSQL PostGIS enabled Database. The Data im displaying is very detailed, i want to simplify it through the simplify() method of Postgis. I duplicated one of my ...
6
votes
3answers
233 views

Create interactive map with no server

I have managed to build a great web mapping application using tiles created from GeoWebCache and a custom gridset, but I now need to add an overlay to the base maps. The only interactivity I need is a ...