Tagged Questions

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

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1
vote
0answers
60 views

How to auto-fill a new point vector in a vector layer?

When I work in-situ I manually add points in my shape-file. I would like that when I add a new point some attributes would already filled with values calculated programmatically. E.g in my first ...
3
votes
4answers
282 views

High resolution and high detail vector GIS coastline product needed

What is the absolute best vector GIS coastline product available globally? I know of a great product for Africa (page 13 of this PDF ...
2
votes
1answer
286 views

pyQgis in stand alone script, vector loading error

I am trying to use the Qgis functions in a stand alone Python script. I m running Mountain Lion OS, 2.7 Python & the Qgis 2.0.1 Dufour. My main problem is that I cannot get started - I cannot ...
1
vote
1answer
82 views

map can only have one feature, after user click

I'm using openLayers 2.13.1. I have a map wih a vector layer and Editing tools. I want the map to have only one feature even if the user keeps adding. So I want the new feature to automatically ...
1
vote
0answers
71 views

Problem in removing dangles in road network [closed]

Im using qgis2.0 , In a given road network i have to remove dangles, for that what should be the tolerance to be added generaly. please help me resolve this issue
0
votes
2answers
237 views

MapServer: How to display and style a Text layer?

I'm trying to display a text layer using MapServer, but I'm kind of confused how to get it to display properly. When opening the .TAB file in a GIS application (in this case, MapInfo Profressional) ...
7
votes
2answers
458 views

What does vector tiled map mean?

I'm working on an application that renders geoJSON into OpenLayers map. The idea is about not having PNG images downloaded from external services (OSM or Bing) but having geo information in geoJSON ...
1
vote
0answers
51 views

Delete polygon underlap?

I am editing a layer in QGIS with severe polygon overlaps. Is there a way to delete the underlapping portions (i.e. the invisible parts) using QGIS? If I import the layer into GRASS using the ...
1
vote
2answers
257 views

Decrease resolution of vector shapes (polygon) i.e. reduce size and number of points in outer ring

I'm trying to get a kmz export down to less than 3 megabytes and am wanting to do so by reducing the number of points in my polygons' outer rings. I've seen this concept in action when it comes to ...
1
vote
1answer
462 views

Check if feature is selected (Openlayers)

I wonder if there is a way to check whether a pointfeature (OpenLayers.Feature.Vector) is selected. I read the API, but didn't find any solution. Any idea?
1
vote
0answers
106 views

OpenLayers - Features in cloned layer changes style with original feature

Please help! My situation is that, I clone() a "newLayer" from an "oldLayer" with its features. Both of them seems correct at first. But then when I tried to change the style of "featureA" in the ...
3
votes
1answer
170 views

Converting map image to GIS

I’m very new to GIS, and I’ve been reading a lot of manuals and information, but I thought I’d ask a couple of questions here. One of my major hobbies is drawing maps of a completely imaginary ...
1
vote
1answer
215 views

How To Show Percentages By Coloring Polygons in QGIS?

I am trying to produce a map with QGIS that has counties shaded according to the percentage of people born in a US Region. For example, counties with a high percentage of people born in the South ...
2
votes
1answer
107 views

heat map of density ratio of 2 layers of points

I have 2 vector layers of points: one with a point for each house in the city (thanks to osm.org), roughly equivalent to population one with a point for each case of cholera in the city I'm trying ...
3
votes
1answer
236 views

How to sum up all field values in QGIS modeler

I am building a model to generate two zones around a point, a 250m-buffer, and a ring of 250 to 1000m, where i recalculate values from an other layer according to the intersections share. The purpose ...
0
votes
0answers
117 views

Identify segments that share a last vertex with the first vertex of selected segment

This has been marked as a duplicate to Connecting line features and determining the length of the longest line but I believe there are some subtle differences. And to be honest I'm not an advanced ...
1
vote
2answers
396 views

OpenLayers: WMS layer above select-controlled vector layer?

Is it possible to display an image layer (WMS or Image) above a vector layer with activated SelectFeature control in OpenLayers? The image layer (radar returns) contains only sparse, semi-transparent ...
5
votes
1answer
155 views

LiDAR Feature extraction specifications/standards

I have vector data representing forests/trees/buildings that have been automatically extracted from LiDAR data. I am looking for specification/guidance for LiDAR derived products, or any standard for ...
2
votes
1answer
299 views

Possible workflows for shaded relief representation as vector

I am looking for a good workflow on how to represent relief on a map as vector (e.g. for further processing in Adobe Illustrator or Inkscape). My inspiration is the present google maps at zoom level ...
1
vote
2answers
130 views

QGIS point sampling tool really slow for polygons?

I have a large field of randomly distributed points (100,000 of them to be precise), and I'd like to get values for a variety of raster and polygon coverages for each point. I've been using the QGIS ...
3
votes
2answers
333 views

How to calculate distances between addresses and cities and coast line?

I am totally new to GIS, and so I apologize if my question is not clear enough. My basic problem is the following: I have about 160,000 Danish addresses with longitude and latitude for each address. ...
18
votes
4answers
13k 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 ...
2
votes
2answers
315 views

Georeference vector linework

I'm new to GIS and a lot of searching didn't answer my specific question so far, so I hope someone can help me here. What I want to do is creating a small web application to visualize election ...
0
votes
1answer
1k views

Convert vector data with irregular points (no grid) to raster with QGIS?

I am aware that how to convert a vector layer to a raster layer is a quite frequent problem and that there are many questions and answers dealing with it. However, none was helpful concerning my ...
2
votes
1answer
140 views

How to delete points which are close to each other?

I have a vector file containing thousands of points. Where points are within x distance from each other, I wish to delete one of the points and keep the other (either by snapping to one point, or ...
0
votes
1answer
114 views

How to increase symbol size of polygons when zoomed out?

I have many small polygon scattered. How do I increase size of polygons when zoomed out in qgis? As seen in the image the symbol appears to be lost when I zoom out. Note: I have created a thematic ...
0
votes
0answers
115 views

Google and Croatia WMS do not line up with shapefiles (500 meter to East)

I am working on a project in Croatia. I can use the WMS files from geoportal.dgu.hr/wms. These line up perfectly with the google maps. As project CRS I use HTRS96/TM which has become standard in ...
0
votes
2answers
68 views

v.what.rast trouble in GRASS GIS 6.4.2

I'm facing a problem using the v.what.rast comand. I'm trying to update the vector "canali" which represents some streams, with the slope value for every single point of the lines. The slope values ...
2
votes
1answer
241 views

How to calculate mean coordinates from big point datasets?

I know there are several questions related to speed issues in QGIS, but I am having problems when running Ftools. I have a vector with ~70,000 points in it. When I run the generate mean coordinates ...
0
votes
2answers
160 views

In grass v.drape works with points but not lines

I got an elevation raster map which I interpolate from a point cloud with v.surf.bspline. Then I digitize a couple of points in a new vector layer. With v.drape I'm able to get a height from the ...
2
votes
1answer
50 views

Conceptually, what's the ideal way to develop detour maps for a large number of nodes

I have a road layer of roughly 30,000 links. On these links, I have a total of 15,000 nodes that are sorted in a point layer. I'm trying to build a detour distance and routing around each asset in ...
1
vote
1answer
85 views

Snap mean coordinate to layer in QGIS and creating MCs for multiple shapefiles

1: I wish to create a mean coordinate for a group of points. However, I would like the new point to be snapped to the nearest point from the set of points used to generate it. How might one go about ...
-1
votes
2answers
99 views

Counting raster points within boundaries in another layer?

I know this question is similar to some out there, but I have tried all the 'solutions' and none of them are working for me. I am using the latest version of Qgis. I have a raster layer with ...
0
votes
2answers
93 views

please Introduce me a free 3rd party library appropriate for showing Geospatial information

Up to know I have used GDAL to extract raster data from geotiffs and then opengl's used to show that raster data. But when it comes to extract vector data with the help of ogr library, what library ...
0
votes
0answers
211 views

How to read vector datasets using GDAL library

Up to now, I have used GDAL in order to read raster information and geotiffs and show them with the help of OpenGL. Now I have a vector dataset, and by that, I mean I have the files with types: DBF ...
1
vote
2answers
722 views

OpenLayers vector does not draw (or re-draw) on zoom level change or layerswitcher off/on

Here is the full code (i'll highlight the important parts after): jQuery(document).ready(function($) { // ...
3
votes
0answers
152 views

Cross-browser marker animation in OpenLayers

Currently I'm trying to implement animated markers in OpenLayers. I'm using PNGs for the markers, set by the externalGraphic style property on an OpenLayers.Layer.Vector. I need to be able to make ...
0
votes
1answer
736 views

provide an alternative “label” when styling vector layer with openlayers

I'm using openlayers 2.12 and I am styling a vector layer using your typical new OpenLayers.Style({ Now, this layer does two things. First , renders polygons from Geoserver, so in the style I have ...
2
votes
1answer
81 views

Is it possible to display two categorical symbolizes for two different attributes in one layer alongside each other in ArcMAP 10.1?

I have a road layer that I would like to display attribute_1 = "speed" on top of the line segment and attribute_2 = "traffic_volume" below the line segment. For each attribute I would like to setup ...
1
vote
2answers
380 views

Custom filters (server side) for Openlayers Vector Layer

I have a vector layer in openlayers with source in GEOJSON (custom php server, which I have in complete control) and BBOX strategy. Vector points contain point sources which have different ...
2
votes
2answers
587 views

Styling OS Vectormap Local in QGIS?

I am attempting to style Ordnance Survey Vectormap Local on QGIS 1.8.0 by using the styling sheets suplied by Ordnance Survey. The styling sheets are available from the OS website ...
0
votes
1answer
142 views

OpenLayers Strategies

Can we use the strategies OpenLayers.Strategy.Fixed and OpenLayers.Strategy.BBOX simulataneously on same vector layer?
1
vote
1answer
1k views

Running Maperitive on a Mac

Really basic question, but I need details and help running Maperitive from my mac. I've tried launching it from the terminal and tried running it through WineBottler. If anyone has experience with ...
1
vote
1answer
275 views

reclassify vector data from multiple source data fields (ArcGIS) (ModelBuilder)

I am using ArcGIS 10.1 and ModelBuilder. I am not familiar with Python. My question is very similar to ReClassify Vector Data Between Values . However that question is about reclassification using ...
1
vote
0answers
190 views

Loading Vector Layer PyQGIS Issues

I am trying to follow PYQGIS documentation for loading a shapefile from inside a script. http://www.qgis.org/pyqgis-cookbook/intro.html I was able to set the datasource and run the QgsVectorLayer ...
0
votes
0answers
75 views

Vector/Raster Intersection - Speedup and replacement for ST_Centroid

I have some raster data which is the altitude above sea level and also some vector data which represents building outlines. What I want to do is grab some buildings outlines and fetch all the raster ...
2
votes
0answers
203 views

How to render a transparent raster layer on top of one or more vector layers with PyQgis?

I been trying to render a map with a 3 vector layers and one raster layer. The idea is that the raster layer should be on top of the other 3 vector layers. The problem is that even when I add the ...
2
votes
2answers
186 views

Convert ASCII Grid Colorized to Raster

I have an ASCII Grid file + .prj file and can visualize this in qGIS. I can colorize it by going to properties and using a Pseudocolor Ramp. However, I want to export this now as a TIFF / Raster. ...
1
vote
0answers
106 views

convert vector with multiple attributes to multiple rasters

I have a vector polygon feature with multiple attributes/fields. Ultimately, I want to convert it to a raster 'stack,' whereby each of the attributes/fields will be a different band of the raster ...
9
votes
2answers
322 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 ...