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Questions tagged [polygon]

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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Joining two vector layers with polygons and then selecting one via other in QGIS?

This could very well be a duplicate question, but i can't find the answer in the site. Using QGIS 3.4, I have two vector layers with polygons and same projections: one with all individual watersheds ...
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35 views

How to generalize or simplify the multipolygon in PostGIS without missing any polygons?

By following the rules from this site, I got the output but some polygons do not come within the simplified polygon. I think the problem is with topology. Is there any solution?
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1answer
33 views

Creating 1 hectare rectangle polygon surrounding points and dividing it into equal sized sub-quadrats in ArcGIS Desktop?

I have a set of points like this: ] I have only these points' information. Now I want to draw a boundary of this points whose size should be 1 hectare (100m x 100m). After that, I want to subdivide ...
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0answers
31 views

GeoJSON layer shows/enables only one row in attribute table in QGIS

I have a GeoJSON polygon layer which I converted from a shapefile layer. The layer opens up in geojson.io, for example, with no problem, displays the table correctly, etc: However, in QGIS the ...
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0answers
37 views

How to create a function for getting a largest polygon from 2 polygons using case statement in PostgreSQL?

CREATE OR REPLACE FUNCTION public.largest_polygon1( geom1 geometry, geom2 geometry) RETURNS geometry LANGUAGE 'plpgsql' COST 100 VOLATILE AS $BODY$ begin Return Case ...
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1answer
29 views

How to calculate extreme point (most north or east etc) of geography(polygon) type in PostGIS

I have a table which include geography(polygon) type. CREATE TABLE place ( name varchar(100), geom GEOMETRY(POLYGON, 4326) ); insert into place SELECT 'place1', ST_GeomFromText('POLYGON((-71....
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1answer
36 views

Extracting admin boundary data from OpenStreetMap?

I'm really just looking to get borders for cities and regions around the world. Ideally in a shapefile format. Does anyone know how I can do that from OpenStreetMap?
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2answers
34 views

Creating time series (NDVI) for each polygon contained in feature collection in Google Earth Engine?

I have an image collection of Landsat 5 and a feature collection of thousands polygons and points (in the example, I only have three). I would like to compute the NDVI (and NDWI) mean for each polygon ...
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20 views

Looking for polygon data for metropolitan areas around the world [duplicate]

So I've been looking for the past 2 days and haven't found any good reliable sources. I've been on OSM a ton and it seems that everything is a different standard. Some cities themselves are as big as ...
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4 views

Draw polygon automatically based on Google Earth coverage map simulation

I have a coverage map in atoll that I can export to Google Earth I need to create the polygon of this coverage area for another study. How can I do it automatically? Coverage map is very scattered ...
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1answer
105 views

How to create a function for finding the largest of 2 polygons by area in PostGIS?

I tried my level in creating the function but it shows error while running. I have enclosed the code here : create function largest_poly (geom1, geom2) returns geometry as $largest_poly$ begin from ...
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1answer
55 views

Overlapping polygons layer order

Is there a way in QGIS to prioritize the layering order overlapping polygons. I have a shapefile with numbers in the attribute table from 1-20. Each number is associated with its own polygon. I want ...
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2answers
27 views

Calculating areas in continuous raster of flood map?

I generated a flood hazard map (raster) of a certain area using ArcGIS 10.5 and classify the result into low 0.1 ÷ 0.5 medium 0.5 ÷ 1.5 high > 1.5 After that, I overlay a Land Use map (...
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0answers
30 views

Is it possible to merge two polygons with a single touching point into one?

Is my understanding correct, namely that two polygons touching at a common point cannot be merged because the result would be a self-intersecting polygon? I know there are dozens of Q&A threads ...
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1answer
41 views

Snapping to sketch' vertices while editing in QGIS?

I'm trying to digitize buildings in QGIS and encountered a problem: after digitizing several vertices in a sketch, I want to place my final vertex in accordance with the first one - i.e 'square and ...
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0answers
7 views

ArcGIS Pro - need to import 3D model then create polygons on 3D model to measure sections for surface area

I am generally new to ArcGIS Pro. I am working on a project using photogrammetry where I am reconstructing 3D models and trying to measure the surface area of different sections of the models. Maybe I ...
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1answer
49 views

Create GeoJSON Feature from FeatureCollection

I have a single polygon feature (no holes, no overlaps) which is currently defined as a FeatureCollection in GeoJSON, with type Polygon (not MultiPolygon). I am trying to use it with an online mapping ...
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0answers
7 views

Is it possible to assign values from polygons to a new layer in an existing raster in R?

I'm a bit of an R novice and looking to see if there is any way to assign values to a raster layer based upon polygons. Some background - I am working on a mining project and have a regular grid of ...
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1answer
26 views

Draw a polygon in OpenLayers with coordinates from a variable?

I have the polygon coordinates defined as a variable. This draws nothing when I use the variable, when the same coordinates are used as such in the polygonFeatureT definition, the polygon is drawn ...
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1answer
84 views

Finding centre line of irregular polygons with QGIS?

I have a set of irregular and curved polygons which I would like to find the centre line of them. I've found some solutions for this problem such as Voronoi polygons but It doesn't work for me. It ...
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3answers
949 views

Voronoi Diagram on a given polygon using QGIS

I am trying to create a Voronoi Diagram on a specific polygon, but there is some issue when dealing with edges. Here is how I do it: Preparing the points for Voronoi and the polygon for the diagram ...
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32 views

Fitting many rectangular shaped polygons into larger irregular shaped polygon in PostGIS?

I am looking to try and find the optimal fit for a number of rectangular shaped polygons into a larger irregular shaped polygon and I haven't found much information about how this could be achieved in ...
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1answer
35 views

Intersecting 2 layers without creating duplication using QGIS?

I have 2 polygons that i wish to combine into one layer, in QGIS. on the first layer (neighborhoods) i have bigger areas (that divide a city to 7 major areas, or smaller neighborhoods). that i wish ...
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1answer
165 views

Splitting polygons and dividing attribute value proportionally using ArcGIS Pro?

I am using ArcGIS Pro 2.3.0. I have two feature classes (pictured below), RED polygons and BLUE polygons. The RED polygons have a numeric attribute, Value1. How can I split the RED polygons with ...
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0answers
10 views

Creating polygon for each day from table with change of area over time (by day) using ArcGIS Pro?

I have a .csv with data in rows over time (date field and multiple attributes for each day) of the same single area - the fields are high temperature, low temperature, humidity, precipitation. I want ...
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28 views

Polygon problem with Wacom on QGIS

I currently have a problem on QGIS with my Wacom tablet and polygonal tools. When I create a shape with the polygonal tool, if I use my Wacom tablet, the cursor moves well, but the path (red dotted) ...
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1answer
46 views

Creating coordinate points based on polygon

I am trying to create coordinate points based on a polygon that I've created in Google Maps and imported into R as an sf object. Specifically I have sample points of physical samples I've taken, but ...
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0answers
84 views

Calculating viewing angle (2D) between polygons and points [closed]

I am looking for a solution to the following problem. I have several points (for example houses) and several polygons (eg forests). Seen from the houses, I can see the forests within a certain angle. ...
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0answers
13 views

Selecting only polygons with a certain variable (polygon) in them using ArcMap? [duplicate]

I have green space polygons for London and also illegal pollution areas in polygons in ArcMap. How would I go about selecting only the green space polygons that have pollution areas in them (so the ...
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0answers
25 views

Selecting only polygons with certain variable in them using ArcMap?

I have green space polygons for London and also illegal pollution areas in polygons in ArcMap. How would I go about selecting only the green space polygons that have pollution areas in them (so the ...
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1answer
19 views

Raster does not clip according to polygon feature

I'm trying to cut my raster to fit a polygon, but it keeps doing this weird thing pictured below. I've tried the following things: Merging and dissolving the polygon into 1 polygon Converting the ...
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1answer
20 views

Removing Overlapping Outlines Within a Single Feature Class

I have a polygon feature that is overlapping itself. Both of the polygons in the image below are from that same feature. I do not want to dissolve the boundaries, but I only want one of the outlines ...
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2answers
57 views

Generating random points within series of polygons according to density using R

I have a city that is made up of a number of wards, each with an unequal population. I would like to generate a set of "random" points within the city, but the randomness is influenced by the ...
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0answers
51 views

Using a Wacom Tablet and pen for QGIS, can I pause my free-hand polygon before I am finished, and then continue?

Is there a way to pause the free-hand tool in QGIS so that I can lift the pen off of the screen, and then continue my polygon again when I am ready? I have learned how to pan while free-hand drawing ...
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0answers
41 views

When using a Wacom Cintiq tablet and pen, can you pan while creating a feature using the freehand polygon plug-in in QGIS?

Is there a way to pause the free-hand tool in QGIS so that i can pan and move over the image and then continue my polygon?
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2answers
90 views

Converting list of polygons to multipolygon using shapely?

I have a list of polygons where each polygon is a wkt form as follows: list_polygons = ['POLYGON ((-88.131229288 41.900200029,-88.12973798 41.900104202,-88.129785999 41.894907769,-88.131352409 41....
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1answer
25 views

Finding Rows Inside other Rows

So I have database with which I want to do the following: Find out which other rows are contained within the geometry of the row in question. To keep it simple, I am finding the envelope/bbox of the ...
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1answer
37 views

Transform geometry of polygons

I am new to PostGIS. I'm making a spatial join, but it does not work. From what I saw it is something of the geometry of polygons. My polygons are saved with the "Geom" field like this (Geom geometry (...
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0answers
26 views

My work closed and now I cannot see the Temporary Scratch Layers [duplicate]

This is my first project on QGIS 3.6.1. Over night my computer restarted and updated itself closing my QGIS work.. I created two separate Temporary Scratch Layers and frequently saved it on my ...
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1answer
13 views

Counting (Multi)Polygons Within (Multi)Polygons on same Table

So I have a table with approximately 10k rows, with each row having its corresponding geometry entry. What I am attempting to do is count how many row geometries are contained/within the geometry of a ...
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1answer
62 views

Calculating minimum distance in meters of two polygons (defined in lat/long coordinates)?

I'm new to GIS and I'm a bit lost in the terms and concepts, so I'm not sure I'm asking a valid question, but I need to calculate the minimum distance (in meters) of two polygons which are defined in ...
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3answers
57 views

Converting raster pixels to vector cells?

Is there any way to convert raster pixels to vector cells? I mean each pixel to a polygon. I tried the SAGA tool 'Raster values to points' by choosing cells option instead of nodes option. As a ...
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2answers
42 views

Identifying polygons that intersect with another polygon using ArcGIS Desktop?

I have two polygon layers, a vegetation layer and a treatment layer. I want to add a field to the attribute layer of the vegetation layer to indicate if any part of the polygon has been treated (...
4
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3answers
389 views

Identifying polygons that intersect with another layer using QGIS?

Using QGIS, I have two polygon layers, a vegetation layer and a treatment layer. I want to add a field to the attribute layer of the vegetation layer to indicate if any part of the polygon has been ...
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0answers
21 views

Use geometry to join Spatial Dataframe

I have two Spatial Dataframe, the first one is the Paris Polling Stations from 2012, the other is the Polling Stations from 2017. They almost have the same geography, it deffers for 20 polygons (2017 ...
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1answer
50 views

Remove edge styles on polygons

I have multiple polygons aligned next to each other. They are colorfilled with "Graduated" style. I have changed "Stroke style" to "No Pen". How can I get the hairline between the polygons to ...
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1answer
27 views

Extracting difference between two shapefiles (not symmetrical difference) using ArcGIS Desktop?

I have a shapefile with polygons that portray survey areas (Pink areas in picture below). I receive a new updated shapefile with additional survey areas, and thus new polygons (Green areas in ...
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1answer
46 views

Quickly find all polygons that overlap with two or more polygons in Shapely

I have a set of Polygons (in Shapely) that I wish to find all intersections that are comprised of overlaps of two or more polygons. I have been working based off the code found in this answer. I have ...
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2answers
62 views

How to inverse the orientation of the holes coordinates of a polygon in geopandas

I have a polygon shapefile which I am reading with geopandas. The polygon contains holes. My purpose is to add a random point inside each hole. In order to create the points inside the holes (...
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0answers
116 views

PyQGIS raster image shifted from vector shapefile

I previously asked a question about my raster image being larger and shifted over from my vector image here, but now I realize that the raster image is only shifted to the left and up from the vector ...