Questions tagged [vector]

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

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2
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2answers
395 views

Determine the furthest driving distance from a road layer to the nearest point of a point layer using OSM/QGIS

In a specific geographic area, I have a road layer and roughly 30 points dispersed around the geographic area as part of a point layer. Both layers are in SHP and PostGIS formats. The records from the ...
1
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1answer
1k views

openlayers trigger hover event

I have a bunch of tracks on screen in a vector layer. I used some hover and select styles in the layer styleMap and these styles are properly triggered by: var highlightCtrl = new OpenLayers....
4
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1answer
1k views

How to prepare SVG images for presentation in OpenLayers?

I have a collection of SVG vector images I need to display on a map, probably using OpenLayers/KML. Is there any way to convert a vector image from SVG to KML? Or would it make more sense just to use ...
2
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1answer
954 views

Why does intersect not calculate polygon areas?

this is strange: I intersected 2 shape-files and the resulting shape does not contain the Shape_Area and Shape_Length of the intersected polygons. Instead the field Shape_Area contains the polygon-...
2
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1answer
1k views

Loading Raster and vector data In MapGuide using Maestro

I am new to Mapguide , working on it for my summer Internship.I have Installed it perfectly. Now the task is to load vector data and Raster data in map Guide (mainly have to load *.shp files and *.tif ...
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1answer
6k views

How to reproject vector datasets in ArcMap?

I want to change one Personal Geo-database projection to another. Kindly give me instructions to re-project vector data.
1
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1answer
79 views

OpenLayers - vector boxes and paths

I'm using OpenLayers to make warehouse map. How to prevent drawing lines (paths) over some vector objects already on the map?
3
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1answer
2k views

OpenLayers - Vector Layer and Google Maps - vector layer and google layers don't seem to be in sync when zooming on Chrome

I am working with a Google Layer and a vector layer in OpenLayers. I was wondering if anyone else noticed any problems with Chrome displaying Google Maps layers on OpenLayers? It seems that when I ...
3
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1answer
533 views

Sum up area left “underneath” polygons in QGIS?

I have an area shape layer and multiple other area shape layers. Now I would like to calculate how much space (square kilometers or percentage of area) of the polygons of this area layer is NOT ...
14
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2answers
487 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 ...
0
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4answers
5k views

OpenLayers (allOverlays): Vector layer not rendered without raster layer beneath it

This is another newbie question. I'm trying to create a map using OpenLayers that comprises only of vector layers from a WFS server. However, I'm thwarted because my vector layer won't render unless ...
6
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1answer
1k views

Generate centroids for vector polygons based on raster and land-use data using QGIS

Although QGIS has the ability to generate centroids for polygons, I am not sure how to generate centroids based on land-use development using raster data. Here's an example of what I'm trying to do: ...
2
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2answers
4k views

How to set cell size for vector to raster conversion in QGIS GRASS plugin?

I'm converting a vector (loaded in GRASS plugin in QGIS (1.7.0.-wroclaw) and would like to convert this to a raster with a defined cell size. At the same time I need a value from the attribute tabel ...
2
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3answers
2k views

Openlayers: Copy shape layer in a vector layer

I have a web-gis application based on openlayers and geoserver. I need to modify a shape layer. I'm able to show the shape using the OpenLayers.Layer.WMS method. In fact i published the shape in ...
1
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2answers
2k views

How to select only areas bigger than x acres?

I would like to create a new shapefile from another area shapefile. The new shapefile should only contain all areas that are bigger than 5 acres (10.000 m²). How do I do this?
1
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0answers
471 views

Polygon symmetry detection

I was wondering if there was any way to create main axis (axis of symmetry) lines for polygons. I have polygons that represents buildings. I will want to find main axes (axis of symmetry) for those ...
2
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2answers
3k views

How to create dynamic map images?

I have map images of my local ward (Areas geo-referenced and drawn using QGIS and Adobe illustrator. Now these maps are in .png format (Raster images). It's not a tile linked to some mapserver such as ...
4
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1answer
506 views

Analysing Information By Vector Grid

I have two vector line datasets and wish to compare the line lengths. While I have already compared the sum of the lengths, I'd like to conduct further analysis down to 250m, possibly lower. I'm ...
5
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2answers
1k views

Is it possible to generate a vector polygon from a polygon on a raster image?

I have a raster map which I have extracted from a government report providing flood extent return frequencies. I want to 'snatch' these flood extent polygons (i.e. convert to vector) and I was ...
2
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1answer
2k views

how to get Coodinates after Resizing a feature Openlayers

I'm trying to display the coordinates of a Feature or vector layer after I use the modify radio button to resize my vector, but it does not work, nor on my drag feature. I'm using afterFeatureModified(...
2
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1answer
3k views

How to stop or deactivate draw polygon control after the first polygon has been drawn in Openlayers

I want to only be able to draw one circle on my map and then disable the control. Below is my code, Any suggestions? <html xmlns="http://www.w3.org/1999/xhtml"> <head> ...
4
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1answer
2k views

Select vectors overlapping a raster

I have a raster layer with travel times from a specified point in my city's downtown. What I'd like to do is select all of the census blocks that lie at least partially within 45 minutes of downtown (...
1
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1answer
357 views

Polymaps / Tilestache tiling grid mismatch

I have set up a basic PostGIS / Tilestache / gunicorn / nginx / Polymaps test environment, rendering my dataset from PostGIS to GeoJSON and shipping it out to be rendered in Polymaps. That works ...
14
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1answer
2k 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 ...
2
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2answers
379 views

How OpenStreetMap data layer works?

OSM map has a data layer and an information panel. How is it implemented? What is a type of the layer and URL of vector data source? How information panel works? Thanks for all!
2
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1answer
612 views

Steps to polygonize raster KML image

I suspect I'm trying to do the same thing as in Convert image in KMZ to polygon. Given a kml displaying an image within a given lat/long boundary, what are the steps I follow to use Quantum GIS to ...
0
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1answer
3k views

How to change events in the Oncomplete Drag function in Openlayers

below is code that works for Openlayers drag function: drag = new OpenLayers.Control.DragFeature(polygonLayer, { autoActivate: true, onComplete: function() {alert('Are you sure this is the ...
3
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3answers
1k views

How do I draw on a vector map in GRASS?

I have a vector map that has two lines. I want to have the two connected. Is there a way for me to draw a line to connect the two? I am using GRASS gis by the way. The two lines that I want to connect ...
1
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4answers
305 views

Looking for compute intensive GIS vector operations

I am looking to make efficient algorithms for those vector GIS operation that take a long time for GIS software like Arc-GIS, Grass etc. I have considered polygon overlay but looking for other ...
3
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1answer
1k views

OpenLayers polygon fill on IE has black shading

I have an odd problem on with OpenLayers on IE6, IE7 and IE8. A newly drawn polygon has odd black shading. In fact, even the line (stroke) has the same black outline. Works great in Firefox, Chrome,...
6
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2answers
1k 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"> <title>GeoRSS</...
3
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1answer
2k views

geometryType property of Vector Layers in OpenLayers

ORIGINAL: I have a couple questions that are focused around the geometryType property with vector layers. When you create a vector layer you can set the geometryType property to limit the geometry ...
1
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0answers
198 views

Can I overlay layers in Dealul Piscului 1970 and WGS84 in QGIS?

I have a 10 Gb ECW file (mosaic of a whole county) that is in Oblique Stereographic projection with Datum: Dealul Piscului 1970. The problem was that no matter the Default CRS for new project was, ...
0
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1answer
1k views

How to highlight track in KML on hover with OpenLayers

I have KML layer with multiple tracks and I would like to highlight them individually on mouse hover. I tried to implement this like in the example found in OpenLayers examples, but couldn't get it ...
8
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2answers
1k 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. ...
16
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2answers
428 views

Toward a protocol for encoding vector data as image

This is a follow up to this question: Creating Vector Polygons with rendering performance like GISCloud? In his answer, Yagi outlines a rationale for encoding geographic information in an image ...
3
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1answer
1k views

Why is Openlayers KML-layer undefined when using permalink

I am working on Openlayers to dynamically load KML tracks on map. I want it to load filtered KML everytime map is moved or zoomed based on viewport and zoom level. I got it working with code below, ...
7
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1answer
245 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 ...
12
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4answers
673 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 ...
3
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2answers
2k views

How to combine polygons in a vector with GRASS?

I need to combine polygons of similar geological classes which are stored in a vector file called geology. I was looking for somethiing like "union selected features" or similar. In the GRASS Book ...
1
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1answer
2k views

openlayers- WFS- Cross-domain problem

I got the typical cross-domain problem when access to WFS layer by using openlayers, XMLHttpRequest cannot load http://XXXX/geoserver/ows?service=WFS. Origin http://XXXX is not allowed by Access-...
5
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1answer
2k views

How to draw or edit curved lines in free GIS?

I'm searching informations about drawing simple curved arrow lines into free GIS like QGIS, in this problem data geometry is CIRCULARSTRING ( a type which exists in latest postgis version) It seems ...
3
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1answer
872 views

polygon map overlay algorithm

There are many algorithms for binary map overlay operation in vector data format which take two layers of map and produce resultant layer i.e overlaid layer as output. I am wondering whether there are ...
2
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0answers
809 views

Creating a sidewalk map for a walkability survey

If I wanted to do my own walkability survey of my city, what tools could I use? I have map data from OpenStreetMap, but I have to consider that streets have two sides (which aren't always accessible ...
4
votes
2answers
1k views

Stylized map workflow: Illustrator to Google Maps / OpenLayers

The aim My current aim is to create a series of (heavily) stylized diagrams and maps. I'm not very familiar with any GIS software, so my weapon of choice would be to use illustrator for creating the ...
3
votes
1answer
2k views

Openlayers Add features performance for 3000 lines

We would like to implement the function of Addfeature in openlayers to draw lines and push them onto a vector layer, and overlay this layer onto open street map or google map. Those lines are draw ...
1
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1answer
224 views

Any freely available vector data in cylindrical projection?

I'm trying to develop an application in PHP to plot various points in Europe from a database, and serve them dynamically on a map. I think this should be relatively straightforward when using a map ...
2
votes
1answer
1k views

How to clean vector segment intersect errors in GRASS

I'm using GRASS to process a vector map. When I export back to .SHP and do a 'Check Geometry Validity' in Quantum GIS it lists several errors of this type... 3,segments 199 and 203 of line 0 ...
1
vote
1answer
283 views

Why is the geonames not loading?

I want to import a geonames file. I downloaded the geonames .txt file from http://download.geonames.org/export/dump/ I used: v.in.geonames input=PH.txt output=ph but it displayed ...
3
votes
2answers
151 views

Obtaining OS MasterMap time series data

I am trying to do a research project on changes in Land Cover in a London borough over time. I have access to OS MasterMap data through Digimap (the service that provides this data to universities in ...