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

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6
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1answer
189 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
404 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
186 views

Assigning costs to a road network : use raster or vector?

I have a road network in a PostGis database (db_routing). In another database (db_environment), I have some spatial features of the surrounding environment (trees as points and water bodies as ...
6
votes
1answer
403 views

Why do vectors disappears when zooming in?

I have imported a .gpx file into qgis and separated the track waypoints using Vector > GPS > GPS tools. When viewing at full extent I can see the original track and component waypoints. However when ...
5
votes
1answer
402 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
4answers
9k 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", ...
5
votes
1answer
776 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
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
2answers
4k views

How to clip a vector feature to the extent of an existing raster dataset using arcpy

I have a clipped raster dataset with polylines (from the contour tool) overlayed (see attached). I am trying to clip the polylines to the extent of the raster dataset, which seems simple enough, but ...
5
votes
1answer
245 views

Help with grid creation in QGIS

I have 235 raster tile 20km x 20km. I need to create a grid to overlay across them...ie the grid itself will be 20km x 20km, with the lines of the grid on the boundaries of the tiles. I am assuming ...
5
votes
2answers
561 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
2answers
500 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 ...
5
votes
1answer
372 views

Easily calculate “roundness/compactness” of a polygon

I am trying to find ways to quantitatively describe the shapes of various polygons. For my project, these polygons represent lakes, rivers, lagoons, and parks. So they can be almost any shape. One ...
5
votes
2answers
175 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
4answers
3k views

How to calculate polygon length and width using open source GIS?

How can I calculate the length and with of polygons using open source tools? By "polygon length" I mean the length of the longest line within the polygon (update: to be correct, I just need the ...
5
votes
1answer
204 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, ...
5
votes
1answer
1k views

How can I programatically create and add features to a memory layer in QGIS 1.9?

I had a working plugin in QGIS 1.8 which read data from an MSAccess database and added it to a series of memory layers. There is some processing involved in the interim so I don't think simply using ...
5
votes
1answer
137 views

GDAL/OGR Determine if dataset is raster or vector

I am writing a script using the GDAL/OGR Python bindings and it is possible that the user may provide a raster dataset or a vector dataset as input. If the user provides a vector dataset, the script ...
5
votes
3answers
1k 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 ...
5
votes
3answers
5k views

Free Mercator, Vector Maps

Are there any free, vector, mercator projection maps available online? I'm not wanting satellite imagery, but more a stylized map along the lines of this: However, I need it to be vector-based such ...
5
votes
1answer
136 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 ...
5
votes
1answer
447 views

Converting polygon values to a vector grid using PostGIS

What is the best way of converting a value from irregularly shaped poylgons to a polygon grid using PostGIS? I have a set of polygons that look like this: and I would like to overlay a grid on ...
5
votes
2answers
199 views

How to download Leaflet vectors in GPX format?

I would like to use the leaflet.draw plugin to allow users to digitize vectors on the map. At the end the data should be downloadable as a GPX-file. Is there any sample that shows how this can be ...
5
votes
1answer
3k views

Trouble exporting from QGIS to Illustrator

I am having trouble getting my files to transfer or export to a vector file. When I open the file in Adobe illustrator there is a lot of information missing. I have tried to "save selection as a ...
5
votes
1answer
149 views

Grid Analysis from samples data

I'm trying to analyze set of samples into vector grids in order to generate average data in corresponding grid.I'm working with 50m separated grids but the size of grid may change over time.That's why ...
5
votes
1answer
525 views

How to emulate a specific vector grid in QGIS?

I would like to analyze data included in a pdf file. The file contains information on characteristics of 16km grid cells for a specific study area. The file also includes a map displaying the grid. I ...
5
votes
1answer
503 views

Vector Building Footprint Resources - Tokyo

I typically know where to look for this data in the United States, but I'm at a loss when looking for building footprint shapefiles abroad. I thought I could find what I was looking for with Open ...
5
votes
1answer
879 views

fTools-Error: “…invalid geometry…”

I want to intersect contours with polygon like in the image below. But i got this error: Warnings: GEOS geoprocessing error: One or more input features have invalid geometry. Some output geometries ...
5
votes
2answers
4k views

Easy way to Create Vector Grid polygons?

We're currently using MapInfo & MapBasic to analyze daily tests results for planning purposes.For each test,exported result may contain empty values (say 999,we know Mapinfo has no NULL values),so ...
5
votes
1answer
840 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 ...
5
votes
1answer
308 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 ...
5
votes
1answer
686 views

Distance Matrix tool in QGIS. How to get result in metric? [closed]

I'm trying to calculate the distance between points in layer with distance matrix tool. And keep getting strange results no matter what. Like this MASTER ------------SLAVE ---------------- DISTANCE ...
5
votes
0answers
52 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 ...
4
votes
5answers
3k views

Problems merging DEMs or other raster datasets? Clipping Raster dataset to vector line?

I have two DEMs that I am going create a hillshade from, and ultimately want one hillshade clipped to a county boundary. I am running into a couple problems, though. When I try to merge the two ...
4
votes
2answers
297 views

Vector Analysis: Determining area of county land mass without water features

Here are the layers that I have: State / Province polygon file (With Area Field) County / Ward polygon (with no area field), but all the polygons are within the state boundaries Water ways for the ...
4
votes
7answers
934 views

Any Good Map Rendering Engines for SqlGeometry/SqlGeography

Can anyone suggest good map rendering engines for MS SQL Server Spatial types (SqlGeometry/SqlGeography)? By rendering, I mean plot the geometries to a common image format such as png or jpeg with ...
4
votes
3answers
2k views

How to calculate orientation of line segments using open source GIS?

I'd like to calculate the orientation of line segments relative to north direction using open source tools. Which tools or functions would you recommend?
4
votes
2answers
3k views

Reclass for vector data in ArcGIS

I've got a vector dataset (in fact, OS MasterMap data) and I want to set the value of a certain field based on the value of another field. For example: Field1 Field2 Building 20 Grass ...
4
votes
4answers
950 views

How to get vector data from OSM to use in QGIS?

How do I get data from OpenStreetMap which I can then edit in QGIS layer by layer? What is the best OSM output and what / how do I get to a suitable input for QGIS? OR...is there another appraach to ...
4
votes
1answer
1k views

Google maps android vector rendering : how do they make it that fast?

Most of the question is in the title. If you are on android (I believe its the same on IOS) and use maps you will notice the quality of the maps app and how the vector maps are drawn in a very fluid ...
4
votes
4answers
4k views

Merge overlapping lines in ArcGIS

I have a polyline shapefile containing a number of lines, some of which overlap. By overlap, I mean that they follow exactly the same path for some of their route, but also have bits that are not ...
4
votes
2answers
143 views

Problem overlapping shapefile and vector in R

I want to plot a shapefile over a raster file in R but I can't make them overlap perfectly: the raster appears to be rotated of few degrees counter-clockwise. Is it a problem with the projection? ...
4
votes
2answers
620 views

Spatial query of raster data

I have population distribution data as a raster layer and exposure contours as vector (polygon) layers. What I'd like to do is use the vector layer to estimate the population indicated from the raster ...
4
votes
3answers
3k views

Openlayers remove previously drawn polygon on starting to draw next one

Objective: At any point of time there SHOULD only be zero/one polygon(s) on a vector layer with a polygon control. I need the previous polygon to be removed as soon as user starts drawing the first ...
4
votes
5answers
588 views

How to save a raster and vector into a single PNG file in GRASS?

I am trying to save a raster and vector into a PNG file. The vector is overlayed on top of the raster map. I was only able to save the raster file into a png using r.out.png but without the vector.
4
votes
3answers
285 views

How to subset X number of features from Shape file in QGIS

I'm looking for a means to take a rather large Shape file and split it out into separate, smaller shapefiles based on number of features. So for example, if I have a file with 1 million features, ...
4
votes
2answers
781 views

Calculate spacing of polylines along transects in ArcGIS

I have a shapefile with a number of roughly parallel lines in it, and I want to calculate the spacing between these lines using a number of transects across the map. How should I go about this? I ...
4
votes
4answers
290 views

Enlarge/roughen the Vector Size of Tiles

Im currently running a GeoServer and my task is to make the vectors rougher thant they are right now. I really dont know where and how the Geoserver processes the data from the DB and how it will be ...
4
votes
1answer
170 views

How to add tree height values to raster / vector data?

I am new to working with raster data and I am trying to teach myself a few things. I have what I think is a simple problem but I can't seem to figure this one out after a few hours of searching Arc ...
4
votes
1answer
58 views

Simple way to compare ranges and distributions of species, looking for correlation and differences between ranges

As a biology student just beginning with GIS, wondered if someone could give me an idea of what tools to go about using to compare the range of 3 species that have trophic effects on one another. I ...