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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1answer
31 views

Shapefile with point or polygon

I'm just beginning with SIG and QGIS. I've been given two shapefiles with cities. One shapefile appears like point shapefile in QGIS, the other like polygon shapefile. The problem is that the ...
0
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0answers
29 views

Clipping algorithm that can make one layer with no overlapping polygons from N polygons

I am looking for an algorithm description / pseudo code for an algorithm that can take N simple polygons and return a new set of polygons that all have been clipped such that there is no overlap in ...
2
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1answer
83 views

Creating shapefile from polygon points for CartoDB?

I have an Excel file that contains polygon coordinates for different areas. The spreadsheet has three columns: latitude, longitude and area name. Each coordinate makes of a part of the boundary of a ...
1
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2answers
75 views

problem combining geometries from all features in a layer as one geometry

I am trying to combine all features of a Polygon layer in QGIS in a python plugin, and am running into this error when I try to run the combine method: "AttributeError: 'NoneType' object has no ...
0
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0answers
63 views

How to load points in a SQL server polygon table?

I have a spatial table in SQL server which stores both points and polygons geometry and I am using the table to return geoJSON for API calls. I want to load some points to this table with shapetype ...
4
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3answers
76 views

Google Earth Polygon surface area to follow the curvature of the earth model

Question: When drawing a polygon in Google Earth with latitude, longitude and elevation values at each node, how do you ensure that the surface area of the polygon also represents the desired ...
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1answer
15 views

Shapefile of South Tyneside borough (north-east England) boundary

I'm looking for a free-to-download shapefile (polygons) of South Tyneside borough. South Tyneside is a metropolitan borough in NE England. Can anyone help?
1
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1answer
51 views

Does QGIS have an autocomplete polygon option like the one in ArcGIS?

I am trying to do digitizing in QGIS, but I do not see an option that I have seen in ArcGIS - autocomplete polygon. I would like to make two adjacent polygons topologically correct, and can not find ...
2
votes
1answer
96 views

How to use GIS data with CGAL?

I read a few posts here at GIS.SE that points to useful algorithms in CGAL. I'd like to test algorithms in CGAL such as medial axis transformation/polygon skeleton extraction, but the examples on the ...
0
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1answer
184 views

Spatial Join in R

I'm fairly new to using R for spatial work so bear with me. I have found questions similar to this but nothing that answers this question specifically enough for me to implement it. I have point data ...
1
vote
1answer
608 views

Aggregate points with same values to polygons

I have a shapefile with 2M measurement points (each measurement point has a resolution of a 1/10). How can I aggregate points around each other if and create polygons out of it? They do not have to ...
2
votes
2answers
149 views

points within a polygon

Since I am a beginner to postgis I am facing problem with finding points within polygons from my table. This is my table structure Column | Type | ...
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0answers
38 views

NDVI polygon from NDVI raster

I am currently working with NDVI data. I found this format which seems to be preferred by our clients: Our maps are made in ArcGIS, I've tried running classification but classes won't allow me to ...
16
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5answers
9k views

How best to fix a non-noded intersection problem in PostGIS?

I'm using a PL/R function and PostGIS to generate voronoi polygons around a set of points. The function that I am using is defined here. When I use this function on a particular dataset I get the ...
3
votes
1answer
42 views

polygon split with predefined area

I am trying to split an irregular polygon into 120 equal area blocks. I also need a buffer around each new block within the polygon. Is this possible in QGIS 2.12.1?
0
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0answers
32 views

Comparison of polygon geometry of 2 layers (ArcEditor)

I´m facing the following Issue: I´m trying to find changes between 2 continuous polygon layers. Polygons that need to be compared dont have matching IDs - to explain, I have polygon X and polygon Y ...
0
votes
2answers
62 views

Remove lines from inside a polygon (shapefile) in r

I have this code which prints the Galápagos Islands. But inside the islands, there are lines that I want to get rid off. How is this possible in R? library(rgdal) library(ggplot2) URL <- ...
0
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1answer
243 views

Serving one large polygon or many little ones from ArcGIS Server?

I´m designing a geoprocessing service on ArcGIS Server using several nationwide datasets. Currently I´m preparing some of the datasets and I´m wondering if I should dissolve my polygon layers ...
1
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0answers
306 views

how to automate changing polygon's shape while keeping its area the same and limiting deviation from orginal centroid? [closed]

I have a polygon that was digitized based upon visually interpreting underlying values of rasters/vectors that represent a natural environment (soil type, surface roughness, slope, elevation, ...
8
votes
3answers
3k views

Order of polygon vertices in general GIS: clockwise or counterclockwise

Two days ago I asked a question about the internal storing order for the vertices of a polygon in ESRI shapefiles. That question was answered (Are polygons stored clockwise or counterclockwise in a ...
1
vote
2answers
964 views

Looking for dissolve algorithm for Javascript

I have three adjacent polygons that together make up a larger shape. I need an algorithm that will dissolve the internal borders leaving only the outside border. An example would be a group of ...
0
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0answers
28 views

Feature Layer parameter showing only Polygon Shapefiles

I have created a Python Tool in ArcGIS where most of the paramaters musts be ONLY Polygon Shapefiles. You can also look on my previous question: Filter the Feature Layer parameter in Python Script ...
4
votes
1answer
44 views

Find polygons that does not contain (any) polygons with PostGIS

New to PostGIS, I have a polygon layer of water catchment areas which are formed by the specific monitoring points along the river upstream. For example, on one river, there could be multiple areas, ...
3
votes
1answer
1k views

How to fill in a ring polygon in QGIS 2.2?

I created a polygon which covers a park. But I want to distinguish some small buildings located inside the park. Consequently, I want to distinguish them and use them as independent patches inside the ...
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0answers
18 views

How to make match two same rasters after conversion "Polygon to Raster?

I am trying to convert two .shp files of polygons of same buildings but with different layers of values into raster. When I do conversion from polygons to raster it always generates bit different ...
0
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1answer
216 views

How to copy closed loop lines into polygon feature class

I'm trying to utilize line contour data to find the volumes of local depressions. To do this, I want to copy the closed loops formed by depression contours into a polygon feature class to find the ...
2
votes
1answer
66 views

2D polygons with height attribute to 3D features for ArcGIS Online

I have a 2D shapefile made of many polygons representing buildings. Each polygon has a height attribute. The goal is to get these into ArcGIS Online's "Scene" feature, showing extruded buildings, ...
11
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1answer
363 views

Is there ArcPy tool for polygon resizing like Scale tool of Advanced Editing toolbar in ArcMap?

I am writing a python script for ArcGIS 10.3. I know about Scale tool in ArcGIS interface but I can't find such arcpy command. It exists? As you can see on the picture the Scale tool works different ...
13
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6answers
5k 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 ...
2
votes
0answers
17 views

layer styling switches after zooming in with no reason

Does anybody have an explanation how it is possible? I have a strange trouble on the following map. The surrounding land layer, which is only a one polygon layer and is styled normally like: var ...
1
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0answers
42 views

Toggling selected feature when using Node Tool of QGIS?

Does anyone know of a way, when using the Node tool in QGIS to edit a polygon, to choose or toggle which feature (within the same layer) is being selected if they share a boundary? It seems to just ...
0
votes
0answers
50 views

Dividing a shape in equal pieces?

I have data in Autocad. As you can see there's a buffer (purple) inside of the blue shape, I want to divide the blue shape to small equal pieces that have the same surface area. What I'm looking for ...
0
votes
1answer
768 views

R solution for 'TopologyException: Input geom 1 is invalid' self-intersection error?

The 'TopologyException: Input geom 1 is invalid' self-intersection error which arises from invalid polygon geometries has been widely discussed. However, I haven't found a convenient solution on the ...
4
votes
1answer
59 views

Reshape polygon to boundary of other polygon

I have two polygons. The first one has a white background and brown boundary. To othr has the pink background. how is it possible to reshape to first polygon to the boundary of the other polygon?
1
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3answers
113 views

Creating line from point based on intersecting line at 90 degrees to line in ArcMap?

I am using ArcMap 10.2/10.3 and I need to create lines from points, so I can split polygons at the created line, as per the image below. So I have to cut the polygon at a 90 degree angle to the line ...
1
vote
1answer
46 views

Joining multiple polygons inside a single polygon in QGIS

I need to somehow "join" information from two shape files: zoning - these are large polygons indicating the zoning code for a moderately large area, typically hundreds of separately owned parcels ...
1
vote
2answers
2k views

accurately find the bounding box of geography polygons

Im displaying polygons on a map and have had issues with the spatial index where the index performs well only for certain data sets (large areas with low density / high density small map areas). I've ...
2
votes
1answer
90 views

Grouping polygons by spatial attributes

I'm working with a dataset that contains millions of polygons representing leased properties. In many cases, there are multiple polygons that are drawn on top of one another (representing multiple ...
1
vote
1answer
43 views

Applying Snap_edit to polygon Geometry Object

I have a project where I am modifying over 1 million polygons (representing tracts of land) to make them line up with the PLSS land grid. My process works (mostly) by cutting up polygons based on a ...
6
votes
3answers
3k views

How to subtract (erase) polygons from polygon?

I have two polygon layers, one is green that represents all non-public right-of-way land. I have another polygon that is just a circle with a specified radius. I would like my output to be a polygon ...
2
votes
1answer
43 views

Grid with data table attached to each polygon

I'm trying to wrap my head around a request a colleague gave for some data visualization. She is performing field observations and for every observation, she is assigning a grid # that corresponds ...
1
vote
2answers
431 views

Correlation analysis of two polygon shapefiles with nominal data

I am working on a research- trying to model vegetation types based on factors affecting their distribution. In that case I have observed a strong relation between vegetation and soil types, from just ...
0
votes
0answers
47 views

Showing city border in Google Maps using OSM data

What I want is a border like in Google Maps: In my solution, i use the overpass-turbo service to get all long/lat for a city. All works fine! But sometimes, borders will be rendered not correct. I ...
2
votes
0answers
36 views

How can I create a grid of polygons from a .csv file or line vector in qgis?

I have a map defined by two seperate reference systems: one is a standard grid coordinate system, the other a series of irregualar polygons. I want to find which polygon each grid square overlays, and ...
1
vote
0answers
43 views

What to do with polygons that were created from a raster file? [closed]

I need some suggestions. I'm working in Arcmap 10.3. I used a NDVI landsat product to find patches of row crops. I then extracted these cells and turned them into shapefiles. I want to measure the ...
8
votes
1answer
395 views

How to smooth adjacent polygons?

I want to smooth polygons which share a common boundary. How can I smooth them so that the shared boundaries stay shared? I'm using Arcgis 10.3
1
vote
0answers
50 views

how to separate land-use type from rows to columns from one shapefile

i am new to using ArcGIS. i have one shapefile of land-use data (100 rows) that has different land-use areas for each neighborhood (which are 10 neighborhoods), what i want is to have one row for ...
0
votes
1answer
38 views

Unexpected results when using ST_Intersection for polygon features

I've to create a spatial intersection of two tables (poly_a and poly_b) containing polygon features. Is there any way to remove unexpected linestring results? CREATE VIEW poly_intersection AS SELECT ...
12
votes
4answers
247 views

How to create lines to visualize differences between polygon features in PostGIS?

I've a PostGIS table polygon_b with some polygon features. There is also a table polygon_a which contains the same polygons as polygon_b but with minor changes. Now I want to create lines to visualize ...
6
votes
4answers
353 views

Filtering features using geometric attributes of polygons in ArcGIS Desktop?

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 ...