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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2
votes
1answer
166 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 ...
11
votes
6answers
3k views

How to find the boundary co-ordinates from a given set of co-ordinates

Given a set of coordinates, How do we find the boundary coordinates. <== Figure 1 Given the coordinates in the above set, How can I get the coordinates on the red boundary. Boundary is the polygon ...
2
votes
1answer
30 views

SQL Server equivelent to Arcmap Intersect for polygons?

I have three different sets of GEOMETRY Polygon datasets in SQL Server that completely overlap. I need to create a new dataset that has a polygon for each unique area of the three layers. So ...
4
votes
3answers
162 views

How to compute the outline of multiple tracks?

I have multiple gps tracks with depth data gathered from the lake. The tracks are overlapping/intersecting. I want to get an outline polygon. I have a multi-line shp. I've tried to diffuse it in qgis ...
2
votes
1answer
313 views

Why does clipping a line layer using a polygon result in an empty shapefile?

I am using QGIS 2.2.0 and want to clip a line layer (roads) so that only those inside a polygon are shown. When I do this using Vector->Geoprocessing Tools->Clip I only get an empty shapefile as an ...
1
vote
1answer
365 views

CartoDB.js - Accessing table fields in hover function

I am new to CartoDB.js and javascript in general, and I am attempting to highlight polygons in response to a mouse hover. My plan of attack attempts to utilize one of the interesting templates ...
0
votes
0answers
34 views

Map polygon property in one shapefile to polygons in another shapefile with same outer boundary

I have two shapefiles covering a region with the same outer boundary. The polygon shape coverage (tesselation) of the two is different. One file (A) has a property assigned to each polygon. How do I ...
2
votes
1answer
75 views

create polygons and fishnets of specific size and orientation and buffers

I want to study 6 areas in the field and in order to do so I want to divide each one of them into smaller areas/parts. What I would like to do is find an average square or rectangle area surface ...
5
votes
2answers
94 views

Automate Splitting Polygons Into Sections

I've searched for similar problems on this topic but can't find a solution. I need to split many, many, many cemetery sections into 8 (mostly) equal pieces each. Each section is for the most part ...
3
votes
1answer
148 views

How to find markers in selected dragbox openlayers 3?

Here is a part of code, draw = new ol.interaction.DragBox({ /* dragbox interaction is active only if alt key is pressed */ condition: ol.events.condition.altKeyOnly, ...
1
vote
3answers
48 views

Summarize the total area of land use polygons within map sheets - how?

I would imagine that at least some of you have encountered similar problems to mine and I´d like to hear how you solved them. I have a map sheet index (a grid as a shape file) covering a large area. ...
0
votes
1answer
73 views

calculate distance between points crossing the antimeridian

How can I calculate the distance between two points (lon/lat) if any of the points exceeds the antimeridian (+-180 longitude)? Im using the distVincentyEllipsoid {geosphere} to calculate the shortest ...
2
votes
1answer
58 views

Create a custom Identify dialog

How can I check if a point belongs to a polygon? I want to create a custom identify tool with edit option. I am using C# and ArcMap 10. My idea is to click on the polygon (building/park/etc) in ...
2
votes
0answers
45 views

Merge vector layers to fill gaps in QGIS

I have a zip code map which I added per zip code data too (a regional director for each zipcode), and then dissolved the map based on the director attribute. As you may or may not know, zip codes are ...
4
votes
1answer
125 views

Fixing orphaned holes in R

I'm trying to perform a union on a common field after merging two adjacent shapefiles. The shapefiles end up with at least one thin sliver of space between them. When I attempt a union I get the ...
1
vote
1answer
47 views

Looking for information on methods or algorithms used to calculate centroid from polygons across software

Looking for information on methods or algorithms used to calculate point centroids from polygons across software. ArcGIS uses a "gravity model" but can someone point me to the math or a paper on the ...
2
votes
3answers
348 views

Combining different geometry types into same feature class?

I've searched the question in this blog. Maybe I don't use the right words but anyway my problem is not present in any post so I'll try to explain my question by opening a new one. I have a polygon ...
1
vote
3answers
81 views

polygons to polygon conversion with attribute name [duplicate]

1) I have a polygon shapefile with 1000 multi-part polygons in it. Each Row of the table is a multipart polygon. 2) I need 1000 shapefiles with 1 multi-part polygon in each. 3) Each output shapefile ...
1
vote
5answers
4k views

How to determine if a polygon is self-intersecting using either ArcPad 8.0 or ArcMap 9.3.1?

I am try to automate a sync replica mxd a nightly basis. The issue I am running into is that in some the of the AXFs (that I get from the users and check-in) have polygons that are self-intersecting ...
2
votes
1answer
62 views

Get feature data from lat long input QGIS

In QGIS, I have a polygon dataset with feature data. I would like to extract data from this dataset using a latitude and longitude. To be more clear, I have a list of 1000 coordinates. I would like ...
0
votes
0answers
33 views

Display Google Maps Polygon Edge Distances in Meters?

How can I achieve this using the Google Maps API? The meters on each side.
1
vote
2answers
58 views

Dissolve tool misses out two polygons

I'm trying to dissolve polygons based on a code number in the attribute table. It all works well, with an exception of two polygons that fail to dissolve - they literally drop out from the output. It ...
0
votes
1answer
421 views

Reverse geocoding polygon co-ordinates?

I have a large dataset of polygons for property sections that I need to reverse geocode. It was recommended that I use a GIS like Quantam to do this however from my research I am not 100% sure if a ...
1
vote
1answer
53 views

QGIS 2.4 How to label a polygon

I have tried labeling a polygon using the layer properties>label function but it doesn't show my label. How and where do I type the text I want and get it to show?
6
votes
2answers
7k views

How to calculate polygon areas and perimeters using QGIS?

Using QGIS, if I load a polygon layer and make a new column, how do I fill that column with the: area of each polygon and another column with length of the perimeter of each polygon?
3
votes
2answers
213 views

Overlaying polygon filled with solid colour with diagonal lines in QGIS

I'm making a vegetation survey map using the UK phase 1 survey colour codes. The code for marshy grassland, for example, is orange overlain with purple diagonal lines. For the moment I've created ...
2
votes
3answers
1k views

Intersect (analysis) of polygons generating empty output

I have previously asked a question on determining the area of polygons with another polygon boundary. Determining the area of each polygon within a polygon boundary? I came to the conculsion that ...
2
votes
1answer
107 views

Clipping Line shapefiles within extent of Polygon shape?

My question is an extension of Vertical lines in a polygon shapefile. Kindly refer to that question first. What you shall see there is a method of generating vertical lines with respect to the ...
2
votes
0answers
41 views

Extracting gridded data from polygon vector layer

So I've spent a few enjoyable (and frustrating) days teaching myself the basics of QGIS and fiddling around to try get some data output I need to drive some calculations. Sadly I'm not having any joy ...
3
votes
1answer
23 views

Bringing attributes of multiple polygons into other polygons?

I need to absorb multible attributes included in block areas into a number of ploygons. In other words, I need to bring block level data into a number of overlaying polygons. The polygons will absord ...
0
votes
1answer
75 views

Intersecting Overlapping Polygons Individually in ArcGIS

Map Layers: -Census Tract Shape File w/Population Data -Set of Store Locations with 5 Mile Buffers (Significant Overlap Between Buffers) I have create feature layers for both and I am trying to ...
2
votes
1answer
43 views

Joining QGIS extent table with shapefile

I used QGIS to find the extents of a list of features from a census boundaries shapefile. I used Vector - Research tools - Polygon From Layer Extent, which creates a new shapefile with a table of ...
1
vote
0answers
43 views

Create Polygon with inner polygons from KML or Shapefiles?

I am creating a windows forms application and I want to create a polygon from a KML or Shapefile as a layer on top of a Google Satellite map. Today I am using GMap.NET that got an polygon object but ...
1
vote
2answers
84 views

Vertical lines in a polygon shapefile

I am working with a GIS problem using a single input of a polygon shapefile. Consider an irregular polygon. I want to draw vertical lines across the extent of the polygon at equal spacing. How I ...
0
votes
0answers
79 views

How to convert multipolygons to a single polygon

I have converted a set of gps points to polygon and then using .makevalid() I saved them in sql server.But It converted them to multypolygons.Is there any way to fix this problem and convert them to ...
0
votes
1answer
243 views

Zip code highlighted in google map

When we search for a zip code in Google Maps we get the area highlighted in the map with a dotted border. How is this calculated? How do they know how to draw the polygon? I'm looking at implementing ...
2
votes
2answers
441 views

Iterating polygons on a SpatialPolygonsDataFrame in R with readWKT

I have fetched some data (39 objects) from my PostGIS database and converted this data into a matrix: rs <- dbSendQuery(con, "SELECT ST_AsText(polygon_accumulation) AS ShapeWKT from ...
6
votes
1answer
188 views

Select by location of doughnut hole polygon

I have vectorized the Corine Land class raster and want to select certain classes that are "inside" other classes. How can I select the polygons circled in blue? All the select by location options ...
1
vote
1answer
53 views

Converting rasters to polygons through cell centers

With arcgis, it is possible to convert a raster image to a polygon representing the boundary of the raster using the Raster To Polygon tool. The output polygon will follow the cell edges of the ...
1
vote
0answers
104 views

Convert polygon data into extreme lon/lat coordinates using QGIS

I'm very new to QGIS. I have a shape file of census blocks and want to use the data to plot points within each boundary using Google Maps api. I figure the best way to do this is to find the extreme ...
1
vote
1answer
66 views

StArea() in sqlserver is in which unit?

I have a problem with saving STArea in sqlserver. Here is a query where I get the area of a polygon: select Geometry::STGeomFromText('POLYGON ((51.3386535086000000 31.7951253522000000, ...
5
votes
0answers
365 views

Grouping analysis of points to divide a polygon into n number of sub-regions

I'm attempting to create n sub-regions from a polygon based on a cluster analysis of a bunch of overlapping raster layers (physical layers, eg: depth, currents, waves). Briefly, I can create a ...
5
votes
4answers
6k 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
226 views

Converting set of points to polygon using C#?

I want to convert a set of gps ponints to polygon.I used a simple loop to convert it to a WKT and than used makevalid() in sql server and save it in a gemetry column in databasae.Is this way right?or ...
4
votes
2answers
82 views

How to programmatically delete all inner rings of a polygon layer?

I have many polygon layers, each layer containing many polygons with inner rings. I know that you can delete a ring manually with QGis (Edit -> Delete ring). I need the python equivalent to ...
0
votes
0answers
46 views

Is there a way to set different levels of transparency (opacity) for a polygon's border and its interior?

I have some polygons which I'd like to display with their interior displayed at a higher transparency than their borders. Right now, I am doing it by creating two separate layers with the same data ...
3
votes
1answer
121 views

Displaying adjacent polygon lines beside each other instead of overlapping

I would like to display adjacent polygons with the line work beside each other, not one on top of the other for that shared boundary. I do not want to edit the polygon boundaries - only want to ...
9
votes
2answers
325 views

Creating an “average” polygon

I found this thread in the old ESRI forums with the same type of problem I am facing today. The solution to the problem is explained in little detail and since I am not an expert, I was wondering if ...
1
vote
1answer
25 views

Intersection of triangle and polygon

I have a triangle and an arbitrary polygon lying on the same plane in 3D space. I need to find the fastest way to determine if these two intersect, one is inside the other, or completely separated. At ...
3
votes
2answers
50 views

Counting number of points in particular polygon for list of individuals using R?

I have distribution points for a set of individuals and a file of polygons-with matching IDs. What I would like to do is to go through and for each individual find the total number of points and the ...