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.
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, ...
3
votes
0answers
168 views
How to write a script to square polygon corners?
I'm looking for a script that will square the corners of polygons that are near 90 degrees but not exactly. Near could be dealt with via a variable, for example within 5 degrees of 90 (85 - 95 ...
10
votes
4answers
400 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 ...
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. ...
2
votes
3answers
202 views
How to calculate exact area of a loaded jpg map in to arcmap?
I calculated the polygon area through arcmap.but i'm not sure that the area is not actual,may be scale is not right.
so how to calculate the exact area of a jpg image?
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 ...
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 ...
4
votes
1answer
277 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, ...
9
votes
5answers
2k views
Get Raster Values from a Polygon Overlay in Opensource GIS Solutions
I have two layers. A polygon-shape-layer with many tiles and a raster-layer containing CORINE 2006 land cover with many categories in a colourmap.
I want to obtain for each polygon in the shapelayer a ...
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 ...
1
vote
1answer
166 views
Is it possible to have self intersecting polygons in GML or shapefile?
GIS vector data for example GML or shapefile contains polygonal data. Lets assume, we have polygon A which has self-intersection which means that the edges in this polygon intersect with each other. ...
5
votes
2answers
323 views
Proper way to rbind SpatialPolygonsDataFrames with identical polygon IDs?
What's the proper R idiom for rbinding SPDFs together when the IDs overlap? Note that here (as is often the case) the IDs are basically meaningless so it's pretty annoying that I can't just make ...
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 ...
5
votes
2answers
336 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
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
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. ...
1
vote
1answer
131 views
gdal_rasterize -at function still won't capture covered pixels properly
I'm currently using the gdal_rasterize tool in bash. My code looks like this:
gdal_rasterize -l $(basename $file .shp) -burn 1 -a_nodata 0 -te -180 -90 180 90 -tr 0.1 0.01 -at -ot Byte $file ...
1
vote
2answers
69 views
How to query points that fall outside their designated regions?
I have a shapefile with 250 points. Each point has a region attribute. In another shapefile I have all the possible regions with their names (it is polyline geometry).
Unfortunately the coordinates ...
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 ...
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
...
5
votes
2answers
276 views
How to enclose clustered points with polygon?
I have a raster with forest (1), no forest (2) data. "1" is represent single/few trees and there is gaps between them. I want to create a polygon around these trees to a forest map. It is not a dense ...
5
votes
0answers
596 views
How to split polygons without ArcView?
I'm trying to split polygons into equal areas. While fishnet sort of works; the areas I'm trying to split don't touch; they're national parks. Fishnet spans the whole area, not just the polygons in ...
9
votes
1answer
344 views
Self intersections for polygons, howto solve?
I have a question about repairing a self intersecting polygon shapefile. I have a shapefile containing Polygons (ZM) which has self intersecting features. If I use the "repair Geometry" tool, it finds ...
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 ...
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 ...
2
votes
1answer
475 views
Convert shapefile in NAD27 from meters to decimal degrees to match xy data?
I have a shapefile of a boundary (polygon) that has the following projection:
NAD_1927_UTM_Zone_11N
Projection: Transverse_Mercator
False_Easting: 500000.00000000
False_Northing: ...
1
vote
1answer
364 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.
19
votes
7answers
8k views
Removing small spaces between polygons
I have a set of polygons representing administrative districts. The districts were digitized by hand, and there are small spaces between polygons where the polygons should be touching. How can I ...
2
votes
1answer
112 views
joining a table from zonal statistics as table with a layer, problem with reserved names
I have a raster file (percentage of total forest killed) and a shapefile with polygons (municipalities). I thought as a first step I would like to find out which municipality shows the greatest ...
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 ...
4
votes
1answer
941 views
GDAL - creating vector from raster
[SOLVED] Good day! I'm looking at either gdal_contour or gdal_polygonize.py to create a vector layer file from a raster file. I can create the vector file using either method, but it's upside down ...
0
votes
2answers
2k views
How to delete polygon in Openlayers
I would like to delete my polygon in Openlayers after i have drawn it.
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<style type="text/css">
html, body, #map {
...
2
votes
2answers
97 views
How can a style be set on a specific polygon using OpenLayers?
Using a polygon id, I want to highlight a polygon, while the mouse is outside of the map area. I can identify the polygon using the following approach:
x = 53;
for(i=0; ...
5
votes
0answers
122 views
How to rotate polygon to find best fit in Mapnik? [closed]
I have a quite simple problem but somehow I just fail to solve it.
There is a polygon and a range xsize and ysize. The x and y size determines the mapnik generated image.
The polygon should now be ...
3
votes
2answers
207 views
How to convert polygon layer to txt files?
Is there any way to convert polygons that do not have coordinates in the attribute table to a txt file with coordinates. I will be using the txt file in a different software (not ArcGIS), so I need ...
2
votes
1answer
579 views
How can GeoJson polygons be colored programmatically using OpenLayers?
I'm experimenting with dynamically setting the color values of a geojson polygon. In my geojson file, there is an attribute for each polygon called pop_den. I am trying to update the fillcolor of the ...
0
votes
1answer
111 views
How to add a label of a point to a polygon
i have several polygons with in each polygon a point with a label (number).
I want to add the label in the polygon to the attribute-table of the polygon it belongs to.
2
votes
3answers
225 views
Zonal Statistics as table creates output but some are Null
Here is my newest issue:
I have temperature as a raster file and different ecoregions of a province as polygons.
What I want to do is calculate the mean temperature per ecoregion.
I succeeded in ...
6
votes
1answer
536 views
Where can I find a Unesco World Heritage List as boundaries?
I was wondering if anyone knows where to find the UNESCO world heritage list with boundaries? I can extract point data from the json feed for the map on the website http://whc.unesco.org/en/list via
...
6
votes
2answers
436 views
Converting point sets to polygon boundaries
I'm trying to convert sets of points to their respective polygon boundaries. I think this is something like a Voronoi diagram or Convex Hull, but not quite. I'm sure there's a technical term for it, ...
1
vote
0answers
57 views
footprint polygon from raster data with postgis
how can I create a polygon, containing the actual outlines (aka footprint) of a raster file with postgis?
I just need the outlines of the data containing parts of the raster.
ST_PixelAsPolygon ...
3
votes
1answer
315 views
adding polygon to database in openlayers
I want to add a polygon to the database. I used the following code. The problem is that I am to able to save in database. Whatever polygon I draw on map it gets save temporary and as soon as I reload ...
1
vote
2answers
183 views
One Polygon Joining to Database with Many matching records
Using ArcMap 10.1.
Is this possible to have one polygon and join to a database/excel with many matching records?
I would like to have 1 polygon but match to 100 corresponding records in a table. When ...
1
vote
0answers
78 views
How to construct a line from points in pyshp?
I am reading a shapefile for a pipeline and what I've noticed is that if I just draw a line from one point to the next (in the order I read them), there will be points where the line terminates, and ...
6
votes
1answer
193 views
How to draw shapes with highest possible decimal accuracy
I am trying to read input of lat and long to draw the shape based on condition.The input is standard array of lat and long with 15 decimal accuracy. I am realizing - I am loosing some decimal accuracy ...
5
votes
1answer
71 views
How do you edit a stack of polygons simultaneously?
Using ArcMap 10.1.
Lets say you have 100 polygons that all are in the exact same shape and in the exact same place. They appear to be one polygon. How would you edit the shape of all 100 at the same ...
2
votes
1answer
105 views
How to join attributes of donut polygon to hole polygon in ArcGIS?
First of all I'm completely new to the realm of GIS and ArcGIS.
Basically I need a reliable way to determine a donut hole's containing donut for a few hundred thousand polygons (where the donut holes ...
