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

learn more… | top users | synonyms (1)

0
votes
1answer
29 views

Multiple vertices after editing giving wrong start and end x, y co-ordinates

I have a small problem which I have been fighting to solve but in vain. Initially I generated some polylines across the river at various locations. I found some of them are smaller in size and not ...
0
votes
0answers
47 views

Shifting Polyline Feature Class

I need to horizontally shift a Polyline feature class (clip1diss) (just one raw) 360 degrees East (deltaX = 360). It would be the equivalent as to "Move" in an Edit session in ArcMap but I cannot ...
0
votes
1answer
51 views

QGIS problems getting layers to line up correctly.

I am trying to add a raster layer and a vector layer to qgis. I have set both of their CSR to NAD83 Oklahoma North State Plane. It doesn't seem to work even with all the files set to those CSR. ...
0
votes
0answers
37 views

QGIS pixel/square cms using scale, dpi

The data (vectors) I'm using are 5cm in resolution. I think that resolution refers to accuracy of the data and not the image resolution. I've produced maps using the QGIS print composer and exported ...
0
votes
2answers
614 views

How to capture contour lines from OSM cycle map as vector?

In QGIS, there is a plugin to insert a OSM cycle map layer, that brings as an image from http. But I can't convert this OSM Plugin layer to a raster image. I can't even imagine how to get the contour ...
0
votes
1answer
11 views

GRASS Add Vector Point

I need to do a viewshed analysis using GRASS. I've got the DEMs loaded; and I simply want to input several (2-4) points (like 41.12345N, 122.34567W from GPS). What is the simplest, most ...
6
votes
1answer
786 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 ...
0
votes
0answers
77 views

Cropping elements from one layer to an element from another

I'm trying to make a hex map of a country (Russia, in this case). To do this, I've opened a map of Russia in QGIS (from Natural Earth), set up my projection, and created a hex grid with MMQGIS. So ...
0
votes
0answers
111 views

changing unit of area from unknown unit to square meters

I am using Qgis 1.8 and I have this polygon.Now I wanted to know the area of this polygon and i have used field calculator and it shows my area as 651692439.under general tab crs is : EPSG:4326 - WGS ...
1
vote
2answers
61 views

How can I change vector grid extents in QGIS?

I created many vector grids, but later I discovered that I need to modify some of their extents, hence, How can I change vector grid's extents (xmin, xmax, ymin and ymax) in QGIS?
1
vote
1answer
73 views

Is there a tool to buffer features with more than one distance value in GRASS GIS?

I´m looking for a tool like Multiple-Ring-Buffer in ArcGIS, but for GRASS GIS to be able to buffer with different distances but only having to start the process once.
0
votes
2answers
74 views

Show only some buildings

How do I show only some buildings? I only need to show 3 cabins in the forrest, but not every house in the whole village around, and the city close by. Maybe some of the symbol buildings in the city ...
3
votes
1answer
233 views

Show alternating contour lines

Is it possible to show only every other counture line? And how do you do that? (Im new to QGIS Lisboa 1.8.0, but even newer to QGIS Dufour 2.0.1, but have used ArcGIS a bit a while ago, and also ...
0
votes
0answers
54 views

ESRI 3D generate file format to ShapeZ

Can GDAL (ogr2ogr) convert ESRI 3D generate file format (class PointZ, LineZ and PolylineZ) to 3D Shapefiles? The format description can be found here: 3D Formats information. The PolylineZ format ...
0
votes
0answers
28 views

alignment of shapefiles in GRASS

I have two shapefiles below. One is in the state plane projection, and the other is not projected. In ArcMap the shapefiles line up perfectly. When I import them to my mapset (using the override ...
0
votes
0answers
132 views

.svg georeference?

How would I go about taking a layer from AI or Inkscape and importing it into Arc? I've got a vector drawing I want to use and I know I need to georeference it but I'm lost as to how. I also can't ...
2
votes
0answers
159 views

How to best intersect vector data with raster data?

I have Open Street Map [OSM] data imported so that I can access the geometry of buildings. I have also loaded SRTM digital height data from NASA from a GeoTIFF raster. I have projected the raster into ...
2
votes
0answers
94 views

Joining csv file to vector layer in Processing modeler?

I am trying to join a simple csv file of values to a vector layer within Processing modeler. The match would be on an id held by both files. The csv file has no geometry. I can do this easily in ...
1
vote
3answers
177 views

How to prepare a multi-colored vector layer?

I need to present a multi-colored vector layer and something similar to below: I need to prepare the vector layer by making use with the data set available in my database. Inside my database, I ...
1
vote
1answer
86 views

Analyzing Raster Data From Vector Layer Buffer

I am using QGIS 2.0. I have satellite images of night-time lights all over earth. I also have a vector shapefile of country boundaries including the largest cities on earth. I want to use buffers to ...
1
vote
1answer
63 views

Calculate 2D line of site from line layer and polygon layer using ArcGIS 10

I'm trying to run an analysis where I need to clip a radiating lines layer by land features to get the maximum distance from the central point to the nearest obstacle. What I have is a large line ...
2
votes
3answers
191 views

How to get a bbox selection of huge shapefile as GeoJSON?

I have a 4.29 GB Shapefile from which I want to extract features as GeoJSON, defined by a bounding box. This should be as fast as possible, because I want to use it in a web application. My first ...
4
votes
1answer
77 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 ...
3
votes
1answer
97 views

Add more info in the attribute table after executing “Line intersection” in QGIS

I have executed the "Line intersection" tool on a road shapefile. This is under Vector > Analysis Tools > Line intersections. I get an output with attribute table having just two columns: type_1 ...
3
votes
1answer
143 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 ...
2
votes
1answer
102 views

Handle a great amount of Markers with OpenLayers

My general Problem is to maintain a lot of markers. For the beginning I want to display all Bus Stops of Berlin, Germany and surroundings as Markers. I already got that I have to use a strategy like ...
1
vote
1answer
82 views

cannot click on points in openlayers

I use openlayers 2.13.1 along with Geoserver and PostgreSQL I have a code for a vector layer , in my openlayers like so //style for layer var style_d = new OpenLayers.Style({ 'fillColor': ...
2
votes
1answer
127 views

graduated labels in QGIS

I've searched on Google but haven't found an answer. The QGIS Dufour GIS provide an enhanced vector-styling interface but is it also possible to graduate the labels like it is possible for the ...
0
votes
1answer
650 views

Draw order (zIndex) of OpenLayers polygons and points in the same layer

My question is similar but slightly different from this one: http://stackoverflow.com/questions/5003349/openlayers-vector-features-z-indexing I have an OpenLayers Vector layer which contains polygons ...
2
votes
1answer
272 views

Creating buffers that will not overlap in QGIS

I am dealing with a .shp with a number of points in it. The distances between points range from ~300m to 5km. I wish to create a 1 km buffer around each point with as little overlap as possible. Each ...
2
votes
0answers
144 views

QGIS: How to reverse vertex ordering in polygons

I am working with an Oracle spatial connection in QGIS through which I am accessing and editing a vector layer. I find that when I edit a geometry, the vertex ordering is reversed (to clockwise in the ...
2
votes
3answers
153 views

Generating a polygon tile index from multiple vector datasets

OK. well this is silly, in that there is no way it should be as difficult as it has been for me to find information regarding how to generate a polygon tile index from multiple vector (contour) tiles. ...
1
vote
0answers
295 views

Updated: Openlayers Vector Layers with Google Map Base Layer (via Grid): Vectors Stick but can't get correct resolution/projection

Revamping this question instead of opening a new one. Previous issue: vector layers were not "sticking" to the map, so when you would zoom in or out the vector layers would "come out" at you. Note ...
0
votes
0answers
165 views

How Can i create a Vector layer from selected features qgis

In my qgis plugin i select dynamically features from a Vector layer. and currently i create a new layer from selection on combining all feature into a new feature: theField = QgsField self.theString ...
0
votes
0answers
112 views

how do I add attribute features to an attribute table which already exists?

Using Verson 2.0, downloaded as normal. I have an ESRI shapefile of my road map for 2006. I have a paper map of roads for 1969. I want to see what roads have been built between 1969 and 2006 (none ...
3
votes
1answer
379 views

Openlayers vector layer don't draw well on chrome (single tile)

I have singleTiled layer in OL (using chrome). The layer don't draw completely unless I pan the map slowly to the south (here is example how the layer keep drawing itself each time I pan) : ...
3
votes
2answers
207 views

Comparing 2 polygon shapefiles for differences [duplicate]

I have 7 shapefiles, each representing a year, all containing lots of polygons (c. 500,000). My aim is to take any 2 of them and compare how they have changed in terms of size and shape of polygon. (i ...
4
votes
1answer
107 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 ...
0
votes
0answers
75 views

Calculating vector statistics in GRASS

I have a points layer, each of points have an year attribute and I want to count how many points in each year. I use GRASS-GIS and its v.univar function: v.univar -e map=mod14_hmao column=year ...
1
vote
1answer
99 views

OpenLayers, Get clustered point's val

I'm working on a map with WMS overlays and a lot of markers, my problem is when I try to calculate the average of points clustered, I've found how to differentiate the behaviour and the label text ...
0
votes
0answers
49 views

Newbie, I want to make a map that shows something along the lines of the following:

What is the average income for housing units (middle, mixed, family, etc.) within a 2 mile radius of parks for the City of Anaheim? or What is the average number of parks within the 1/2 mile radius ...
2
votes
1answer
3k views

OpenLayers Vector Layers: adding and removing features VS. redraw/refresh

I am currently using addFeatures and removeAllFeatures in my code to get the desired results and this is working OK. However, I have been asked to ensure that the vector layers are not being ...
1
vote
2answers
231 views

Splitting discontiguous vector feature in QGIS

I'm a QGIS novice. I'm trying to correct a map of Europe in QGIS, and it's incorrectly assigned Corsica to Germany. I can't seem to split Corsica off of Germany because when I use "split features" to ...
0
votes
1answer
2k views

How to clip a line layer based on polygons with QGIS?

I have a line layer and a polygon layer. Both files have the same SRS. I want in a new shape file only the lines covered by the polygons. I tried in QGIS the Vector -> Geoprocessing -> Clip ...
2
votes
3answers
336 views

Ordnance Survey 1 km Grid

I am wanting to get a copy of the OS 1km Grid layer. I have found these previous questions: Ordnance Survey grids - download or generate? and Ordnance Survey Grids But neither provide the ...
4
votes
1answer
296 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 ...
0
votes
2answers
465 views

How to Resolve Inconsistent OpenLayers vector position Over Google map [duplicate]

I have an OpenLayers map with a Google base layer and an OpenLayers vector layer on which people can draw their own bounding boxes using the DrawFeature control. I have found that, as you zoom in, ...
6
votes
2answers
451 views

Convert points to lines with Python GDAL

I have a dictionary with points. The points are derived from a raster (see image below). The points are not sorted and are not in order. The dictionary looks for example like this: pointDict = {0: ...
4
votes
2answers
164 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? ...
1
vote
1answer
185 views

Openlayers Vector Event Popup with Textbox

The Openlayers map here: http://www.dassh.ac.uk/demonstrations/valmer/demo5.html has an event to add a vector layer, plus creates a textbox on the page below. Ideally I'd like the click event to add ...