On a map, a closed shape defined by a connected sequence of x,y coordinate pairs, where the first and last coordinate pair are the same and all other pairs are unique.
1
vote
3answers
266 views
How to create one KML per polygon (from one Shapefile)?
I have a shapefile containing hundreds of polygons. I need to create a kml of each of the polygon. Is there any way that I may not have to deal each polygon individually and my polygon file may give ...
4
votes
1answer
259 views
What is the best way to connect spatial data with attributes in Excel table?
I have many attributes which are stored in an Excel table. They refer to USA counties. I need to somehow connect those attributes to polygons in some format (don't know which is the best) and ...
7
votes
2answers
487 views
How to create a heat map or density map from stacked polygons in ArcMap 10
I have a polygon shape file that has many overlapping features. Each feature represents an area used by polar bears. So some of the polygons overlap and some don't, and there are separate clusters of ...
6
votes
2answers
69 views
summing up over an area based on a distance related function
Through a field study, we learned that the density of a bird species in the forest was related to the distance to forest edge: ln(density) = 1.89*(distance to edge) + 0.34
Now, for any forest ...
3
votes
3answers
149 views
How do I sort polygons by their latitude?
We have a set of polygons which we would like to sort and number according to their latitude. This will make it easier for local authorities to relate to the numbers of the objects.
I have looked ...
1
vote
0answers
172 views
How to clip the contour map with the polygon using R software?
Hi I am wondering how can I create the contour lines from the discrete x, y and z dataset and then add the shapefile to cut the contour lines by polygon.
I want to clip the contour map by the shape ...
3
votes
0answers
159 views
Polygonize vegetation area from Landsat7 RGB using QGis / Bilko?
I'm trying to extract the areas with vegetation as a polygon-shape from a landsat7-image, 30m resolution, RGB, using QGis 1.8 or Bilko or (hopefully in the near future) ArcGIS. The area is in Northern ...
2
votes
1answer
76 views
What is the PostGIS function for retrieving buildings by road side?
I want to get information of buildings by the road side only. Assuming that the building table has multi-polygon geometry and the road table has multi-linestring geometry, what would be a pgSQL Query ...
0
votes
3answers
213 views
Calculate 'Rectangle' Coordinates Given 2 Points and width [closed]
I want to create a rectangular polygon using two points as guides.
So let's say a journey starts in Egypt and ends in London, my polygon should have 4 points:
10 miles further from London than Egypt ...
4
votes
3answers
84 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, ...
0
votes
0answers
81 views
Regional statistics from a dataset (point inside a polygon aka region)
I am relatively new to GIS and I am trying to do some geographical analysis on same data I've collected. The dataset I have consists essentially in a file with the following format:
...
5
votes
2answers
291 views
How to achieve an “inner glow” effect on polygons drawn using the Google Maps v3 javascript API?
Is it possible to produce an "inner glow" effect on polygons drawn using the Google Map v3 javascript API?
If not possible using the vanilla Google Maps API, is there a 3rd party tool that can do it? ...
2
votes
1answer
116 views
How to remove a hole from a polygon in OpenLayers?
Is it possible to remove a hole from a polygon by using OpenLayers?
How can I do so?
3
votes
1answer
70 views
digitizing (tolerence) error in line data
I have designed a large number of boundaries. For accuracy, I took lines in patches from different data sets and merged them into one. Now I want to turn them into polygons from lines. I every second ...
3
votes
0answers
98 views
Closest set of points to another set of (predefined) points
I have 10 sets of points which I call templates that I have manually classified from 0 to 10. Each point is a X, Y coordinate in a text file. Each template has 5-8 points.
I have new sets of points ...
6
votes
1answer
184 views
QGIS define hexagon area around mapped points
I am using QGIS to map a number of radio antennas (for mobile network).
Once I have the layer of the sites (done), I would like to assign to each site a coverage area (envelope). I could achieve that ...
7
votes
1answer
209 views
How to rectify polygon-shapes in Quantum-GIS? [duplicate]
I have some polygon-shapes in qgis-1.7.0 and want to ensure that every polygon is a rectangle. See image below.
Is there any way I can do this in quantum-gis (or any other f/oss)? Or how can I ...
10
votes
3answers
210 views
How to improve drawn shapes in Quantum-GIS?
I have a polygon-shape in qgis-1.7.0 and want to fix overlays and gaps between the edges of adjacent polygons. See image below.
Is there any automated way to do this in quantum-gis? Or any other ...
3
votes
1answer
323 views
How to enable “snapping” in Quantum-GIS while drawing polygons?
I tried to draw polygons in qgis-1.7.0 and I somehow can't find or failed to find the "snapping" option. I'm used to ArcGIS-10.0 where you have some snapping options, like placing points of polygons ...
7
votes
3answers
307 views
How to sum up values of neighbouring polygons?
I hope that you can help me with the following problem: I have a vector (polygon) layer. I would like to add an attribute to the layer that - for every polygon - sums the values of a specific field of ...
2
votes
0answers
66 views
Cannot reselect polygon after modify
I've got various vector layers on a OL map.
On one layer I have a few draw controls. If I draw a polygon I can select it (the whole pop-up thing works). This also works for all the other features.
...
0
votes
1answer
170 views
OpenLayers polygon fill not working with GeoJSON file as source
I'm trying to visualise some data in a custom shape on a map, and I'm stuck with styling it.
I'm currently using the openlayers framework in combination with a geoJSON file that I generate in code. ...
3
votes
1answer
223 views
Qgis analysis on polygon
I have a data table mapped and the table also contains further information of interest, beyond the lat/long of the specific data points.
I want to be able to draw a polygon and then simply have a ...
10
votes
4answers
403 views
How to colour polygons with a completely transparent fill using MapServer?
Is it possible to fill polygons so that they are completely transparent in MapServer? I want to have a black background that is slightly opaque, and wherever there is a polygon I want that to be ...
1
vote
0answers
22 views
area weighted average for overlapping polygons [duplicate]
Possible Duplicate:
How to use NASS county level crop data to estimate crop acreage in hydrologic regions?
It seems like an easy problem but I don't know how to go about it.
I have two ...
3
votes
2answers
121 views
How to filter out multipart polygons and then buffer?
I've written a small script trying to accomplish the task described in the question title. It basically looks like:
in_fc = '...' # Some shapefile goes here
# Get the fields (column names) of the ...
3
votes
1answer
144 views
Merging multipolygon data into a polygon
I have a MultiPolygon representation of some shapes in POSTGIS, I am trying to convert them to Polygon data.
I tried, st_geometryn(r.geom, 1) but that didnt work because the way polygons are ...
1
vote
0answers
183 views
How to handle postgresql/postgis geometry type errors in a function?
I have created the following function in PL/SQL to make a polygon from a set of linestrings:
CREATE OR REPLACE FUNCTION _myfunction(
_fid integer,
_rid integer
)
RETURNS VOID AS $$ ...
4
votes
1answer
147 views
Extracting donut holes as separate layer in QGIS
Does anyone know how I can extract the holes in a polygon layer as a separate layer in Quantum GIS? An example could be a country with a number of lakes cut out of the polygon - I need the lakes.
I ...
4
votes
1answer
278 views
Dissolving specific polygons inside SearchCursor with Python in Arcmap
I have a layer with catchment polygons. For those that are smaller than a certain size, I want to merge with an adjoining polygon (namely the one downstream). In the attribute table I have a GridID, ...
5
votes
2answers
259 views
How to combine data from overlapping polygons?
Here's what I'm working with:
Shape file of the current 32 Congressional districts for all states
Shape file of the tract boundaries for Texas
A DBF format table of Hispanic counts and proportions ...
3
votes
0answers
74 views
Why doesn't Polygonizer copy the line ids to my polygonized shapefile?
I am trying to convert a line shapefile into a polygon shapefile using Polygonizer plugin, and when my new polygons are created all the cells in my id field are "Null", although I have clicked "copy ...
3
votes
2answers
103 views
Determine density or cover from a raster layer that has been clipped by a polygon
I am a very new GIS user using ArcMap 10. I have a raster layer of tree canopy that I have clipped so that the layer is in a polygon that is a circle with a 2km radius.
I have done this for four ...
1
vote
1answer
89 views
Why is ArcMap 10.0 editor deleting some added vertices and simplifying polygon?
I am using ArcMap 10.0. I am trying to edit (and add) vertices in a polygon.
I start editing, (using "Edit Vertices" tool), and add many vertices in the polygon.
Then when I am done, I save the ...
5
votes
2answers
337 views
How to sum pixel values within a polygon zone in QGIS?
I have two layers: a raster layer and a vector layer (polygon). I can see the values of the raster pixels but I don't know how to combine them with information from the polygon layer. More ...
2
votes
0answers
93 views
How to dissolve polygons that have been split back into their original polygons?
I had a feature class containging about a thousand polygons.After some processing such as intersecting, dissolving, merging, more intersecting, I ended up with a feature class of about 6000 polys. ...
2
votes
2answers
318 views
Problem creating polygon features using ArcObjects / ArcGIS 10
I need to create a grid of polygons. Each polygon is rectangle, thus has 4 corners (vertices). When I create polygon features using ArcObjects they seem to have wrong geometry, which results in wrong ...
2
votes
1answer
105 views
Obtain normalized raster average per polygon?
I have a raster that contains percentages of total forest killed plus a polygon layer that defines different zones.
My goal is to find a good statistical representative that describes the forest ...
1
vote
0answers
67 views
Creating responsive interaction with tiled maps
I think I may have two conflicting aims but...
I need to create responsive Choropleth map very similar to http://leafletjs.com/examples/choropleth.html or
...
1
vote
2answers
120 views
information from a shapefile to another shapefile
I am very new to GIS and learning by myself so what I'm about to ask is possibly quite basic.
I am using QGIS.
I have a shapefile, which categorizes areas (land cover) by numbers (corresponding to ...
6
votes
2answers
151 views
How do different GIS systems determine a Polygon's interior?
I'm interested in understanding how real-world GIS systems and their data encode Polygons.
Specifically, how do they resolve the ambiguity of a Polygon's interior on a sphere?
Background: in 2D, ...
6
votes
1answer
195 views
Generalize large polygon-file
I have a large polygone file with landuse information (6 classes). Its vectorised from a raster classification so the polygons are all angular. Any of my tries to generalize with v.generalize (sneaks, ...
0
votes
0answers
10 views
Insert name of a polygon and add to database using openlayers [duplicate]
Possible Duplicate:
How do I set attributes when creating vectors using OpenLayers and WFS-T?
Hi everyone I am newbie to openlayers. I have developed an application which provides WMS/WFS. ...
0
votes
0answers
29 views
Point to Polygon [duplicate]
Possible Duplicate:
Create new polygon layers from postcodes latitude & longitude
I'm running QGIS 1.8.0
I have a list of points that I need to convert to one polygon. So far I have ...
5
votes
1answer
64 views
Geographic locators within Polygons
I have a list of geographic locators and a boundary file. In QGIS, is there any way merging them together to create a lookup saying this boundary contains these locators? Not the number the actual ...
1
vote
1answer
366 views
QGIS, how do you break segments of a polygon, ie break 1 polygon into 2 or more?
I have a polygon but would like it to be in broken up to put into different layers. I can't work out how to do this.
4
votes
5answers
282 views
Python loop Polygon to raster not working
I want to convert a large number of different shp polygons to raster in ArcGIS 10.1, using an existing field column "class" for the new raster classes. I am not very fluent in python but I thought ...
6
votes
3answers
226 views
What geometric attributes do polygons possess, and how can these be used to filter features?
Given a polygon featureclass containing many polygons of different sizes and shapes, which geometric attributes (area, perimeter, etc) could be used to filter the polygons? It's probably best to ask ...
3
votes
1answer
112 views
Splitting polygons leaves null values
I'm trying to split polygons with overlaping line features, using Split Polygons tool from Topology toolbar. The problem I encounter is that only one from new polygons have old attributes and others ...
10
votes
6answers
451 views
How do I make a heat or Choropleth map that uses polygons in QGis?
I've been playing around with the heatmap plugin for QGIS and I am wondering if it is possible to make heatmap with using a similar plugin/tool that uses polygons as well as points?
I would like to ...
