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

learn more… | top users | synonyms (1)

4
votes
8answers
1k 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
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
332 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
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
3answers
155 views

Can you recycle shp and shx files in shapefile fishnet (vector grid) where only dbf data changes?

I'm periodically getting data from an external partner that is bound to a very large fishnet (vector grid) in shapefile format. The fishnet itself sits at around 400~ megabytes, but the only data that ...
4
votes
2answers
4k 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
205 views

Checking if polygon fits inside another polygon using ArcGIS or QGIS?

How do I check if one polygon fits inside another polygon? Furthermore how do I automatically check if one polygon fits in other polygons of my shapefile? I have a shapefile with thousands of ...
4
votes
4answers
1k 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
3k 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
6k 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
196 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
3answers
2k 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 ...
4
votes
5answers
670 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
4k 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
2answers
844 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
2answers
1k views

How/Where can I find vector data for building footprints in Texas?

I've done a lot of research on this topic over the past 8 or 9 months, but I'm a GIS newb, so I may have overlooked some possibilities for finding/extracting this data. A short list of resources I ...
4
votes
4answers
8k views

Looking for an annotated vectorial map of the world

I'm looking for an annotated vectorial (PS/SVG/...) map of the world (+countries). Wikipedia contains many vectorial maps (e.g: http://commons.wikimedia.org/wiki/Category:Blank_SVG_maps_of_the_world ...
4
votes
1answer
54k views

What is the difference between Vector and Raster data models? [duplicate]

From: http://support.esri.com/en/knowledgebase/GISDictionary/term/vector%20data%20model vector data model: [data models] A representation of the world using points, lines, and polygons. Vector ...
4
votes
1answer
123 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 ...
4
votes
3answers
468 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
4answers
5k 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 ...
4
votes
1answer
385 views

How to know contents of column names in GRASS?

I am using GRASS to extract a specific area from a vector map. Here is the script that I am running: v.extract PHL_map out=makati where="AREA_NAME = 'Makati" The problem is, I don't know what are ...
4
votes
2answers
907 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
308 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
497 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
208 views

How to horizontally align irregularly shaped point symbol to vector layer in QGIS?

Fairly new to QGIS and searching a method to graphically align my point symbols in the direction of the vector. The symbol represents a water valve in an irregular shape in close proximity to a vector ...
4
votes
2answers
615 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 ...
4
votes
3answers
11k views

Hover/Popup feature problem

im really having an issue here. I am trying to realise a map where i can hover over the features and they get highlighted (works), then i want to be able to click them (works) , i also want a div to ...
4
votes
4answers
2k views

Openlayers WFS Vector Layer Rules dont get applied

i have a script which applies rules to wfs.vectors. the script works fine in firefox and all the rules get applied, but somehow when i open the same file with the internet explorer 7 / 8 , only the ...
4
votes
1answer
74 views

Which system of units does the unit 'degree' belong to?

Let us say that I would like to store latitudes and longitudes like this: lat 35 degree long 80 degree Which system of units does the unit 'degree' belong to? It is not really a SI unit nor a ...
4
votes
2answers
118 views

Calculating average raster to point distances within census tracts

I have some experience using ArcGIS, but mostly with the field calculator in the attribute table/spatial joins, so I apologize if I say something that doesn't make sense. To provide a bit of ...
4
votes
1answer
94 views

Comparison of vector file formats

Does anyone know of a chart or table that would explain the benefits / shortcomings of the different vector file formats, eg. .shp, .gml, .kml, .gdb. It seems that ESRI shape is still quite prolific, ...
4
votes
1answer
333 views

Raster to vector with gaps in Landsat ETM

I need to find size of water area from a raster (jpg) using QGIS 1.8.0-Lisboa. The raster is a Landsat image with gaps of data in it. I used Polygonize, but the output file shows wrong polygon size ...
4
votes
1answer
4k views

Relabel Vector Points in OpenLayers

I have created two labeled vector points on an open layers map. I'm trying to change the label text dynamically. I tried changing the values where the stylemap gets the values from and calling ...
4
votes
1answer
754 views

How to extract features from a vector layer?

I have a vector file containing the river lines of an area. I want to extract a specific water line from the vector. I used: v.db.select but it only displayed: ...
4
votes
2answers
140 views

3d vector and geometry operations in open-source GIS

There is some really good open-source software available to work with 2D vectors. For example QGIS has operations like buffer / clip / dissolve / select by location / join attributes by location... ...
4
votes
2answers
75 views

How to show labels for all polygons in a layer, even with 'NULL' values?

I have a polygon layer which contain information on property name, number of trees within the polygon, average height, and min- and max height values. My problem is, I want to label each polygon with ...
4
votes
1answer
149 views

Suggestions for vector format for contour map

I've been trying to create a contour map of a DEM and I've been running into some technical problems. I want to avoid artifacts, so I'm using a DEM of the entire area. This means the size is rather ...
4
votes
1answer
524 views

Loading a multipoint shapefile in R

This issue has only been raised in the community once, two years ago, to the best of my knowledge. I think it's high time to raise the issue again! readOGR, from the rgdal package, cannot handle ...
4
votes
2answers
477 views

How to delimit hinterland boundaries among multiple city centers?

I need to delimit city boundaries basing on centers'magnitude. CenterA's employment/CenterB's employment = (Distance from centerA to break-point E/Distance from centerB to break-point E)^2. AB=AE+BE. ...
4
votes
1answer
2k views

How to use a sld file with Openlayers using OSM data?

My app, made with openlayers, displays building data called from overpass api. var data_url = "http://overpass-api.de/api/interpreter?data=(way[building](bbox);node(w););out body;"; //main working ...
4
votes
1answer
94 views

Reduce number of vector field arrows in qgis

OK, now that I have figured out how to get my vector fields in qgis, I can't figure out how to reduce the number of vector arrows on the map. Is there a setting for how many vectors are sampled? ...
4
votes
1answer
509 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: ...
4
votes
3answers
1k views

Calculate neighborhood statistics for polygons?

I've been searching around for the answer to this (including here) and have yet to find it. I'm interested in finding out how to calculate a 'neighborhood sum' for vector, polygon data. I am aware ...
4
votes
1answer
109 views

Comparing floor and roof areas using QGIS?

I am pretty new in this GIS topic and I would really appreciate if someone can help me with this problem. I am doing a research for university that shall show the available roof area for ...
4
votes
1answer
235 views

Removing some bands or layers from a tiff using gdal

I have been working on a multiband raster image. It is a pix image. I need to just work on the 26 bands that are raster files and not the 4 bitmaps that are are also included in the pix image. I could ...
4
votes
3answers
827 views

Vector Mapping for iOS?

Are there any vector map data providers with API's, that i can use to build my app on iOS natively (not on a webview). Specifically im looking for: For a library/framework that uses existing map ...
4
votes
1answer
103 views

Extract Z information from different vector layers in ArcMap 10.1

I have 2 different vector layers, Layer A detailing the area of different polygons and Layer B having similar size polygons with z values instead. I would need to combine Layer A with Layer B so that ...
4
votes
1answer
409 views

How to measure the distance of multiple points to a line

I have two shapfile in QGIS to which I am trying to find the distances between. I have a shoreline which is a vector line and then I have hundreds of data points in the ocean. What I am trying to find ...
4
votes
2answers
2k views

OpenLayers - Get features inside a polygon

In my OpenLayers map I allow users to draw an ad-hoc polygon vector. Then I need to get all the features from a WFS vector layer that fall within the ad-hoc polygon. Here is the code I have that ...