Tagged Questions

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

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4
votes
1answer
94 views

How to cache PostGIS views?

Does anyone knows if there exists a caching system for views or queries in postgis? I have a system that gives information through a webpage using a postgis view as backend. The problem is that, ...
2
votes
1answer
253 views

GML and GeoJSON vector layer can not display in Firefox and Chrome

I have following codes. It works perfectly in IE (GML and GeoJSON vector layer was loaded), but not in Firefox and Chrome without any errors noticed. Please help me to fix this problem. Here is the ...
2
votes
1answer
177 views

How to get all Vector layers from OpenLayers map?

OpenLayers.Map object exposes a method call getLayersByClass. How do I use this method to retrieve all of the Vector layers from the map? I tried map.getLayersByClass("Vector") but this returned an ...
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 ...
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
3answers
267 views

How to update feature positions with clustering in OpenLayers?

I have an OpenLayers 2.12 map with a vector layer with a cluster strategy. All the static behavior is how I want it. Now I'd like to add the possibility to update the features' position. I do this ...
0
votes
1answer
104 views

Vector data(point) is drawn in wrong place on map (OpenLayers)

I need to show a map (world map, used default OpenLayers WMS) and one point on it (with events like onhover, etc). Here is my code: var options = { ...
2
votes
0answers
184 views

Reclassifying a field in vector files in ArcGIS

ArcGIS has a reclassify tool that works with Raster files only. Is it possible to have the same functionality for a vector file? On the basis of one of the fields in a feature class, the tool ...
2
votes
0answers
115 views

Overlay Shapefile onto Geotiff

I have a Geotiff map and I want to overlay a Shapefile onto it. Ideally I want to specify a 'nice' style for the polygons e.g. have them opaque (for now all polygons should be the same). I want to ...
1
vote
0answers
136 views

Qgis 1.9 on Ubuntu 12.04 constant crashes as soon as I try to do anything

I can get a google earth physical layer open but as soon as I try to open a vector file it crashes-just goes away-no error message, nothing
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 ...
3
votes
1answer
315 views

adding polygon to database in openlayers

I want to add a polygon to the database. I used the following code. The problem is that I am to able to save in database. Whatever polygon I draw on map it gets save temporary and as soon as I reload ...
2
votes
1answer
231 views

LoadingPanel - Waiting for Vector & WFS loading

I have vector layer with WFS protocol. and because I have a huge amount of data, there is a while before features loaded on the map. So i need to tell user to wait a moment until they load by ...
1
vote
1answer
189 views

Openlayers - Vector Layer - Combining hide/show features using style property

I am trying to filter vector layer features according to their attributes. I have 4 check boxes: type_1, type_2, shape_1 and shape_2 Note that I am using Extjs for interface. at beginning I could ...
3
votes
3answers
603 views

How to sum raster image values with vector overlay

I'm new to this and haven't been able to figure out how to do this on my own. Here's what I want to do ... I have two files: a raster image of land use data and a vector-based shapefile of my ...
1
vote
1answer
83 views

Are There Any OpenSource GIS Software Programs With an “Interactive” Rotate Feature Option?

![Rotate feature option][1]Sorry if the question is too simple, but are there any open source GIS software programs available with an interactive "Rotate vector feature" option? Eg : ArcGIS has it ...
1
vote
1answer
98 views

BBOX strategy to load all features?

Since I have no way, other than using BBOX strategy with my vector layer + wfs protocol Is it required to use BBOX strategy with WFS protocol in OpenLayers? I'm wondering if there is a way to force ...
3
votes
1answer
181 views

MapServer Symbol with Two Colours

I'd like to symbolise a point dataset with a square (or circle) using two colours. This is useful for displaying values collected on both sides of a road (for example). I created two symbols, a ...
3
votes
1answer
121 views

Measurement units not returned in project CRS units

I am attempting to calculate area of country polygons using the field calculator. The layer in question is unprojected WGS84, but I have set the project CRS to World Equidistant Cylindrical ...
1
vote
2answers
367 views

Is it required to use BBOX strategy with WFS protocol in OpenLayers?

is it a must to use BBOX strategy with WFS protocol in Vector layers ? I cannot display this layer without BBOX strategy: vLayer = new OpenLayers.Layer.Vector("Test", { styleMap: new ...
0
votes
0answers
23 views

I cannot remove BBOX strategy from vector layer [duplicate]

Possible Duplicate: Is it required to use BBOX strategy with WFS protocol in OpenLayers? I used to apply a BBOX strategy on my vector layer (WFS protocol) : vLayer = new ...
1
vote
2answers
227 views

Why is my shapefile not visible in Tilemill?

I have 3 layers of vectors (shapefiles) that I've loaded into Tilemill. However, nothing is visible in Tilemill. What am I doing wrong, and what should I do to get my map to show up? This is part ...
1
vote
2answers
377 views

How to show vector features in OpenLayers after hiding it?

I did change some vector features style (through check-boxes) using style property : var features = layer.features; for( var i = 0; i < features.length; i++ ) { //features[i].style = { ...
2
votes
1answer
963 views

How to change an OpenLayers vector layer from automatic to manual get request?

I have a web server that returns a FeatureCollection in JSON. I was getting this using the code below, which works perfectly: var vectorLayer = new OpenLayers.Layer.Vector('geoJSON', { ...
3
votes
2answers
77 views

Dissolve column based on attribute in another column

I have 3 columns within a polygon layer I'm working with. Column 1 = Landowner, 3 different values Column 2 = Parcel, N different values Column 3 = Management type, 5 different values I would like ...
0
votes
2answers
89 views

How to apply v.transform on a set of vector layers (GRASS 6.4)?

I have 64 vector layers, all of them must be warped using the v.transform module; the pointsfile is the same for all vectors. How can I apply the transformation recursively to all layers? I'm not ...
2
votes
2answers
362 views

Measuring the distance between lines and points in QGIS

Using QGIS - I have a vector of fault lines. I have point data in the form of a csv which I have also loaded into QGIS. I need to know how far each point is from the nearest fault line then enter ...
3
votes
1answer
338 views

OpenLayers 2.12 + click handler + get the name of the vector

Basically, I add several vector layers (KML content got from jQuery GET) in this way: var layer1Vector= new OpenLayers.Layer.Vector('activeInfo'); layer1Vector.addFeatures(featuresLayer1Vector); ...
1
vote
2answers
199 views

How to print a vector layer over Google map? “Physical Printing”

I use Geoserver, Openlayers, Extjs and GeoExt to build an app. I am trying to get vector layer on Google map printed with pop up a Print dialog, I tried : var targetElement = Ext.getCmp('mapPanel'); ...
3
votes
2answers
84 views

vector layer, no more editing is allowed

I have a polygon vector layer with already 529 objects but without any attributes so far and now I get the message that shapefiles without attributes are treated as write protected. What can I do to ...
1
vote
1answer
64 views

How to extend lines in Grass

I have a set of vector lines in grass which I need to convert into polygons. However, because of bad base data, the polygons don't always close. To fix this, I need to extend each disjointed line by ...
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 ...
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!
1
vote
0answers
241 views

Vector layer shifted on OSM map: why?

I've defined the following map: Proj4js.defs["EPSG:31258"] = "+proj=tmerc +lat_0=0 +lon_0=13.33333333333333 +k=1 +x_0=450000 +y_0=-5000000 +ellps=bessel ...
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 ...
5
votes
0answers
206 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
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 ...
2
votes
1answer
83 views

Is there anywhere that I can obtain global UV data in either raster or vector format?

I'm looking for some UV data (currently with no spatial or temporal resolutions in mind, but ideally split into UV-A and UV-B) for the whole earth. Can anyone recommend a source for data like this or ...
4
votes
3answers
3k views

Customizing Popups in Openlayers

Is it possible to customize the shape of popups in OpenLayers? For example, I am creating a pop-up using the following approach: var popup = new OpenLayers.Popup.FramedCloud( "popup", ...
6
votes
3answers
924 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: ...
0
votes
1answer
112 views

QGis : superimpose 2 rasters georeferenced (adjustment)

I am pretty new in QGis and I encounter the following problem. I have 2 rasters, let's say, "cadaster" and "tranchot". The raster "tranchot" was georeferenced from the raster "cadaster" with QGis. ...
9
votes
2answers
491 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 ...
1
vote
1answer
117 views

Color depending on attribute

I'm trying to set the color of a vectorlayer feature depending on the feature attributes with PyQGIS. How do you acces the attributes of a vectorlayer feature?
0
votes
0answers
115 views

OpenLayers allOverlays with Vector Layers only

In OpenLayers I want to create a map from Vector data only like in the example http://openlayers.org/dev/examples/all-overlays.html . My code is the following: var map function init() { ...
2
votes
2answers
418 views

How to render a multi-layered (raster + vector) map to a file (PDF, SVG or JPEG, PNG)?

When using OpenLayers I can compose a map with several layers which is displayed nicely by my browser, but I need to do the same server side (no browser composing the layers), and I'm waiting a image ...
1
vote
2answers
87 views

How to join polygons and lines vector maps from openstreetmap?

I am struggling with the data format OSM gives me: I want to use OSM data for routing, but all round-abouts and parking lots are not in the lines layer. They are situated in the poly(lines) layer. ...
4
votes
1answer
1k views

OpenLayers, zoom to vector layer extent

It seems quite simple thing to me, but I get an error. map declaration map = new OpenLayers.Map('map_element', {... projection : _projObj.mercator, displayProjection : _projObj.wgs84 } layer ...
6
votes
3answers
612 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 ...
1
vote
1answer
596 views

OpenLayers : How to make a marker fixed [duplicate]

Possible Duplicate: How to skip drag event to stop a feature being dragged I've created a map and added markers to baselayer on click by using this code : vectorLayer = new ...
5
votes
0answers
51 views

How are the edges of a polygon defined? [duplicate]

Possible Duplicate: Are long lines in shapefiles to be considered geodesics or straight lines in the 2D latlong space? In various representations, such as shapefiles and kml, polygons are ...

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