A coordinate-based data model that represents geographic features as points, lines, and polygons.
41
votes
6answers
990 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 ...
35
votes
7answers
5k 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 ...
22
votes
6answers
28k 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 ...
17
votes
3answers
392 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?
...
14
votes
2answers
273 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 ...
13
votes
6answers
4k 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 ...
13
votes
3answers
8k 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 ...
13
votes
3answers
961 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 ...
12
votes
2answers
334 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
4answers
344 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
874 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
2k 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
1answer
357 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
2answers
392 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
306 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
1answer
7k 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 ...
9
votes
1answer
516 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 ...
9
votes
2answers
492 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 ...
8
votes
2answers
3k 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 ...
8
votes
2answers
520 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. ...
7
votes
5answers
502 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 ...
7
votes
3answers
897 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
520 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
2answers
93 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
269 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 ...
7
votes
2answers
142 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
245 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
613 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
4answers
1k 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 ...
6
votes
2answers
794 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
3answers
925 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: ...
6
votes
1answer
2k 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
3answers
4k 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 ...
6
votes
1answer
539 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
2k 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
323 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 ...
6
votes
1answer
112 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
3answers
1k 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 ...
6
votes
1answer
350 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
1answer
562 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 ...
6
votes
1answer
152 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 ...
5
votes
1answer
181 views
How to determine optimal windmill placement to maximize production?
How can I add automatically the maximum number of points (dots) with 6m diameter and 100m distance each point from other into an area. The dots will present the windmill base (6m) and I want the ...
5
votes
1answer
231 views
Where can I find European City boundary data?
Does anyone know any sources for free European city boundary data?
Thanks!
5
votes
3answers
2k views
Creating a raster surface of overlaps from vector polygon shapefiles?
Basically what I'm trying to do (in ArcGIS 10) is to compare three vector files in order to create a 'comparison' raster layer. I tried using Data Comparison (under Data Management tools) but it ...
5
votes
1answer
592 views
Programmable buffers using GDAL and python
Is there a way to programmatically generate buffer layers for vector layers using GDAL and python?
5
votes
3answers
5k 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 ...
5
votes
2answers
316 views
How to check whether a layer is vector or not in OpenLayers?
am not sure whether this is a stupid question or not.. but I am wondering how to dynamically check whether a layer object belongs to OpenLayers.Layer.Vector class.
Thanks for any replies!
5
votes
3answers
2k 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 ...
5
votes
2answers
145 views
Vectorize cell boundaries in GRASS
I need to vectorize the cell boundaries of a raster map and I have forgotten how to do this.
For instance, if I have a raster map of a region that is just map=1 with a cell size of 500m, I would ...
5
votes
2answers
418 views
Distribute points respect to features using Quantum Gis
I want to know if there is any tool to make points with respect to selected features in a theme?
Using: vector, investigating tools, regular points you can do it but not with respect to a selected ...
