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.

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5
votes
0answers
177 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 ...
2
votes
2answers
544 views

Selecting Part of a Polygon

I have a dataset, in shapefile format, for agricultural land grades in England. It is divided into 7 categories in its attribute table. As the file is a large file and I only want a small section I ...
3
votes
2answers
2k views

How to change the vertex style for editing?

When I use drag feature, then the circles on the polygon edge has the same style. For example, this OpenLayers site. I need to change it, I mean they need to be a different color. What is their ...
3
votes
2answers
494 views

How to select polygon features that have their centers outside of another polygon feature class

Since I only have Incorporated area feature class, how can I select census blocks that are in unincorporated area? Or not within any incorporated areas? Thank you. John
1
vote
3answers
587 views

How to calculate forest area of a bitmap (jpeg) map?

I have a map of 1:50,000 scale map in .jpg format. Can i calculate the land area of forest,lakes etc from arcmap.Anybody can give me the step to do it? And I want to know what is the coordinate ...
0
votes
2answers
357 views

How to retrieve a single polygon from a multipolygon layer in GeoServer

I have a multipolygon layer in GeoServer. The layer represents states within a country. I want to enable a user to search for a specific state, and then only the selected state to be displayed on the ...
2
votes
2answers
411 views

count features in polygon shapefile A that fall within each feature of polygon shapefile B

I have two polygon shapefiles, each of which contain multiple (possibly overlapping) polygons. Is there some way, using GRASS, to calculate the number of polygons belonging to shapefile A that fall ...
2
votes
3answers
319 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?
2
votes
1answer
407 views

determine whether a circle intersects a county boundary in postGIS

I'm using PostGIS 2.0.1 and need to determine whether a circle (center + radius) intersects a county boundary (polygon). The query I'm using is this: SELECT DISTINCT(u.id) FROM siteareas_poly sa, ...
6
votes
2answers
2k views

Finding long axis of irregular polygon using ArcGIS Desktop?

I need some help in how to find the long axis of an irregular shaped ellipse using ArcGIS Desktop. I have found the centroid but don't know how to determine the longest distance.
4
votes
1answer
387 views

Sub-dividing a polygon into smaller polygons

In OpenStreetMap data, some large areas are tagged with a residential=yes tag. Actually within this large polygon there are multiple smaller (rectangular) houses (which are actually not drawn as yet). ...
2
votes
2answers
712 views

FME Donut Hole Extractor

I am using FME to fill in some small holes within polygons. I have used DonutHoleExtractor to split these out, however I have found the output via the HOLE port also brings existing 'filled' holes ...
3
votes
1answer
769 views

how do I get the “outer mantle” of a polygon shape file? (without joining all the polygons)

I am interested in finding all the vertices of all polygons which are not on the inside the most outer polygoin that can be formed in a shape file: Here is how I get all the vertices: def ...
20
votes
3answers
2k views

Packing Polygons within polygon

I have a Boolean raster. In the grey areas of the raster I would like to fit a given size polygon within a contiguous extent. Basically, I have an irregular polygon, and i would like to "fit" a ...
3
votes
1answer
210 views

Create new polygon layer based on areas of varying numbers of stacked polygons

I have several species range maps (as polygons) that overlap/stack. From this, I am trying to identify areas of highest biodiversity. Ideally, I'd like to create a new polygon layer, where 1 part is ...
2
votes
1answer
158 views

Merge section polygons in PLSS

I am trying to merge quarter quarter sections of polygons from PLSS into a quarter section. However, I also want it assigned to correct Township/Range/Section while merging. I know I can hand merge ...
0
votes
2answers
1k views

Calculating shape perimeter/area per zone in ArcGis 10

How can I calculate geometrical features of polygon (perimeter and area) per zone (similar to zonal stats for rasters)? I have a square fishnet (approx 20x35, 1 square kilometer each) and I need to ...
1
vote
2answers
304 views

Clip raster to multi raster

I have a raster aerial photo. I have county wide parcel data. I want to clip/screen shot the raster at each individual parcel. Think of this application - a post card with an image of your house ...
9
votes
3answers
7k views

How to smooth/generalize a polygon in qgis

Is it possible to smooth or generalize a polygon in qgis? Ìs there a plugin available like the generalizer-plugin for lines? I could convert my polygons to lines, smooth them and convert them back to ...
3
votes
1answer
361 views

SQLServer generating invalid WKT

I am a GIS novice using SQL 2008, with C# and the NetTopologySuite WKTReader type to work with some geometries. I have some data which I have been able to save into the database but when I read back ...
1
vote
2answers
498 views

How to combine “positive” with “negative” polygons

I have 2 polygone classes (1 and 2). Inside the polygons are holes (white). Now I want to combine them with the polygon in witch the holes are. Understand? Sorry for that bad english... The white ...
10
votes
6answers
2k views

Where can I get neighborhood boundaries?

Besides Zillow's creative-commons licensed neighborhood boundaries shapefiles, what sources of neighborhood boundaries are there? Not just in the US, but all over the world. Free/open source is ...
2
votes
3answers
658 views

Split polygon with holes to get several hole-less polygons

Unlike this thread I actually need to split the polygons into several hole-less polygons. I'm not sure on how to approach to this problem. I have polygons with holes of many diferent shapes, like ...
3
votes
1answer
441 views

How to display only one pie chart for polygon features in QGIS?

I'm working with Qgis on a project and I have a small problem. I have to do some demographic research and therefore I have a .shp file from a given country with 10 districts for example. Now, I know ...
1
vote
0answers
140 views

identify the fraction of raster cells and listing all the cell values in every polygon

In Arcgis 10 I have a netcdf file that maps the fractions of cropland in the world from 1700 to 2007. I extracted the years that i needed as raster layer format (continous data from 0 to 1) and now, ...
2
votes
3answers
354 views

Is it possible to make a routable graph from Polygons?

I would like to know if it is possible to make a graph with pgrouting 1.05 on polygons. What I mean is that I have to make a graph on a database without roads but with polygon geometry. I would like ...
2
votes
3answers
1k views

Accessing coordinates of polygon

I have designed a polygon in a web page and the coordinates are stored in the database of the type polygon. However when I check the database, I find GEOMETRY - 120B under polygon field. What does ...
2
votes
3answers
3k views

How to aggregate points to polygons using ArcGIS Desktop?

I am trying to aggregate my data points to the polygons so that I could find out how many points I actually have in each polygon, and then export the data contained within each polygon to further look ...
0
votes
1answer
260 views

How to remove polygon under other one?

Hi, lets say that green polygon is under red and part of blue with yellow stripes is also under red polygon. how can i make one polygon from every polygons that intersects my main ( red ) polygon ...
8
votes
1answer
3k views

Postgis - Converting 'geometry_dump' data type to a 'geometry' type

I am working with a dataset of property boundaries that has had ST_Union() run on it, thus all the polygons appear as a multi polygon in one row of a table. I would like to separate these out so I get ...
3
votes
2answers
768 views

Merging polygons that intersect by more than a specified amount

I am working with a dataset that contains a subset of property boundaries in a local government area, thus my dataset is made up of several thousand properties but not all are touching. Since it is a ...
1
vote
1answer
629 views

How to color markers based on polygon area?

I have a map with around 317 markers and each marker is the center point of a polygon. The polygonal area varies throughout, so I want to represent the markers in such a way that the polygon with the ...
8
votes
5answers
7k views

How do I convert a Polygon into a single or all Points?

I want to convert polygons into points. I know how it's done in ArcGis and I think this may sound trivial but it's a serious issue :/. I'll appreciate any hints :)
3
votes
1answer
1k views

Changing the scale (generalisation) in ArcGIS 10

I have 2 polygon layers, accordingly 1:10 000 and 1:500 000. I want to generalize the first layer from 1:10 000 to 1:500 000. I tried using Simplify polygon tool, and since these scales relate to ...
5
votes
2answers
3k views

Removing sliver polygons in ArcGIS Desktop?

I unioned 2 layers into 1 layer, and it created sliver polygons. I used the elimination tool to merge them with neighboring polygons. As as result, it merges all sliver polygons to only one polygon ...
6
votes
1answer
571 views

Filling a polygon with lines using Postgis

i need to calculate a specific distance in an area. The distance is calculated from parallel lines in a polygon, And i need to find out how many parallel lines (with x meters distance to each other) ...
1
vote
2answers
407 views

Label inside top left corner of polygons

Does anyone know of a tool or procedure to automatically place a label in the corner of a polygon, rather than at the centroid? I am using Mapinfo and know that I can manually place the label ...
7
votes
4answers
1k views

Output PostGIS geometry data as centroid or polygon depending on zoom level (GeoServer)

This is what I want: when I zoom out, cities of the country should appear as points and at a certain level when I zoom in, I want them to appear as polygons (showing the area of the city and ...
3
votes
3answers
508 views

Selecting polygons with a minimum internal straight line value - ArcGIS 10

I have a map of polygons representing forest stands. I am trying to sort through them to find those polygons that have a minimum internal distance of 200 m in a straight line (my field sampling will ...
2
votes
1answer
1k views

How to make a predetermined Polygon (Circle) From 4 Coordinates, The Radius and Center Longitude and Latitude in Openlayers

I know how to make a predetermined Polygon in Openlayers (see below). Please have a look at http://studio.netnrg.co.za/dev/rnd/blake.loizides/openlayers var feature2 = new ...
12
votes
5answers
4k 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 ...
0
votes
1answer
362 views

Tiff raster display with polygon layer

Does any body have an idea about why *.tiff images are not displayed when added as raster layer to QGIS after adding a vector layer which has a polygon geometry? SOLVED !! In fact the tiff is ...
3
votes
1answer
3k views

How do I rotate the polygon about an anchor point using python script?

I know there would be no tool in arcpy module as such but mignt have in third party modules. I however tried taking the vertices of the polygon and moving using the below formula. but did not get the ...
3
votes
0answers
268 views

How to get all intersections between two simple polygons in O(n+k)? [closed]

Can someone help with a following problem: report all intersections between two simple polygons in O(n+k) where n - is a total number of polygon edges and k - is number of intersections. As a result - ...
2
votes
1answer
720 views

Openlayers Polygon not visible

I have just recently started playing with mapping but have had limited success. I have been able to create/display markers, but in my current project I am trying to display zipcode areas by creating ...
6
votes
2answers
13k views

How to combine adjacent polygons sharing similar trait into single polygon?

I have a large dataset of habitat classes which I have further simplified down into my own unique classes. However, it resulted in there being habitats adjacent to each other with the same forest ...
4
votes
3answers
1k views

How to Clip a Vector File based on certain Raster Values?

I need to clip a vector file based on certain values of a raster (Slope > 2%). I can´t find a direct way to do it. Trying to vectorize the raster first didn´t work. Is there any tool (ArcGIS or ...
3
votes
2answers
917 views

Generate non-overlapping shapes from a buffer

I have a collection of points, and I need to generate shapes around these points. Let's assume that these points are locations of offices and that the shapes are the 'area of responsibility' around ...
6
votes
4answers
8k views

Getting polygons of all countries and ISO-3166-2 subdivisons

In order to do reverse geocoding lookups to find a country (as ISO-3166-1) and the subdivision (as ISO-3166-2) for given coordinates I am looking for a way to get all polygons of all countries and ...
2
votes
1answer
3k views

How to set polygon opacity on openlayers?

I have some prolems showing polygons in openlayer. I want to divide one city in areas. For the moment I have zona1 and zona2. I took lat and long from google maps so I think they are correct. My ...