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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743 views

How to draw a polygon given a distance and bearing in QGIS

Apologies if this question has been asked before I'm not come across it. I want to draw a polygon given a length and a bearing, basically a square with lenght 1m. I cant seem to manage it with the ...
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4answers
4k views

Clip raster using shapefile into multiple rasters using ArcGIS Desktop?

I have a raster file representing a large area and a shapefile of 30 polygons representing watersheds. I would like to clip the raster with the shapefile to create 30 rasters representing each ...
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4answers
1k views

Creating polygons as % of original area using ArcGIS Desktop?

I have a polygon shapefile and need to create new polygons, within the originals, as % of original area. I used buffer by field (Field= new area as %) but the buffers are created in circles around ...
4
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2answers
146 views

“GIS” Mapping on Monument - Scaling

I have a Baroque tombstone for which I have to map the damage phenoma. Normally one can use a vector drawing programm but one has always two boundaries between the different polygons. Questions: Is it ...
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1answer
833 views

Iterate features on SpatialPolygonsDataFrame in R

I have a SpatialPolygonsDataFrame object. Is there way to use apply on this object rather than using a for loop to iterate features in this object?
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3answers
2k views

Clipping Vector File based on certain Raster Values using ArcGIS Desktop?

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 an ArcGIS tool I could ...
4
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2answers
64 views

How to place only one symbol on the centroid of a multipart polygon?

I am using QGIS version 2.14.1 (Essen). I would like to place symbols on the centroids of my data. The problem is that some of my data has multi-part polygons, which means it places the symbol at the ...
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2answers
339 views

Dissolving/Unifying Ill Behaved/Irregular Polygons in R

I'm working on a project involving bringing together multiple subjects circling difficult to find parts of an image. The output from users is pretty awesome. Cool, right? However, what I want is ...
4
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1answer
2k views

Extract raster value to polygon

I am trying to extract raster values within multiple polygons. It would be nice if I could choose between say the maximum or an average raster value within the polygon. For example, I have created ...
4
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3answers
202 views

Select the most distant vertex from polygon's centroid using ArcPy

I have a poligon and the polygon's centroid. I want to select the most distant vertex from centroid (picture: point A). I used arcpy.FeatureVerticesToPoints_management to create a feature class ...
4
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1answer
551 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 ...
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2answers
4k views

Creating donut holes without losing existing polygons using ArcGIS for Desktop?

Using ArcGIS 10.1 for Desktop is there a way to do a similar operation to creating a donut hole or island in a polygon without losing the existing features? I have mapped small lakes as several ...
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2answers
1k views

How to average values in a point layer with respect to polygon layer in QGIS?

I am new to GIS and have the following problem: I have 2 layers: a point layer with a column that contains numbers (pollution index from specific measurement point) and a polygon layer with different ...
4
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1answer
4k views

How to select and copy a group of polygons in QGIS?

I'm new to QGIS. I opened a few shapefiles that cover Europe. Now I want to select a smaller area and if possible copy the polygons in this area so I can work with a smaller set. How should I do this ...
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2answers
4k views

How to find polygons within polygon using ArcGIS Desktop?

I am new to GIS and ArcGIS. I have a problem I need to solve: I have a set of polygons, some of which enclose other polygons. They are lake polygons, and within lake polygons, are smaller island ...
4
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2answers
146 views

Clip polygon using buffer

I'm very new to QGIS, so apologies if this is a daft question. I've been trying to resolve my problem for a couple of days and I can't get anywhere. I have searched for similar issues here on SE but ...
4
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2answers
65 views

Get the 2 points immediately before and after a given point in PostGIS

In the picture below: The given point is C, I would like to select A and B, but not Z (which is closer to C than B but it's not immediately after in the LineString). Note that C is always ON the line ...
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1answer
83 views

How to get the list of QgsPoint from a polygon Layer in pyqgis

I have a little question about how to manage the points in a layer. from qgis.core import * def run_script(iface): layer = QgsVectorLayer(layerType.Polygon+'?'+crs.psg_4326, ...
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1answer
2k views

Extracting intersection areas in R

I have two polygons. One contains fields(X,Y,Z) and the other contains soil types (A,B,C,D). I want to know what area of every field contains which type of soil. I tried the following: ...
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1answer
479 views

Changing raster cells values inside of a polygon to the closest cells just outside the polygon!

I have been wrestling with this for a while and couldn't find out how I can do this. I want each cell of a raster inside of a polygon boundary to have the value of the closest cell just outside of the ...
4
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1answer
2k views

combine raster and polygon values in R

My question is similar to this one Get Raster Values from a Polygon Overlay in Opensource GIS Solutions but I think I need another step. I have a polygon layer of ecoregions which I brought into R ...
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3answers
641 views

How to subset X number of features from Shape file in QGIS

I'm looking for a means to take a rather large Shape file and split it out into separate, smaller shapefiles based on number of features. So for example, if I have a file with 1 million features, ...
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2answers
1k 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 ...
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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 ...
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2answers
5k views

ArcObjects - Finding the intersection of a polyline and polygon?

I have a polyline and polygon. The polyline will intersect the polygon at two or fewer points. I would like to get these intersection points as X and Y values. EDIT: Here is a quick code sample using ...
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1answer
5k views

Converting tax map polygons from Shapefile to table of map number and corner coordinates

Fairfax County, Virginia provides a Shapefile here which shows the boundaries of the tax maps as polygons. Each polygon simply consists of four corners, and what I'd like to do is create a table ...
4
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1answer
82 views

Find out if overlaying polyline matches polygon centerline in qgis

I have a polygon and a polyline and I need to find a scientific way of how close that polyline is to the actual polygon centerline. Is there any way of doing this in qgis? Any extensions, models, ...
4
votes
1answer
109 views

Clipping raster file in ArcMap over the extent of polyline shape

I have a calculated raster file, overlayed on a shapefile with lines (like on figure) I would like to clip the raster in ArcMap (since it is an interpolation and out of the vector shape it is mostly ...
4
votes
2answers
142 views

How to export a polygon based on elevations using a DTM or a DEM

I have a LiDAR generated DTM and a DEM (accurate to 10x10 feet). I am trying to export a polygon within a boundary which includes all elevations below a specific number. Seems like this should be ...
4
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1answer
98 views

Creating shapefiles using textfiles in QGIS

I have a shapefile in QGIS which has polygons in it . There are several other attributes for each feature . I want to add another attribute to each feature . The value for this attribute is available ...
4
votes
1answer
795 views

Leaflet JS add GeoJSON shape as a hole in a polygon

I have a dataset which already contains geojson. I can add it to my map with the following line of code. L.geoJson(data.geojson).addTo(map); And I get this But I want to achieve this, where the ...
4
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1answer
591 views

postgis: cluster/group points based on distance

We have a set of thousands of points and want to group all of those which are within 100m distance from each other (to get the centroid from each group). A first idea was to build 100m buffers around ...
4
votes
1answer
2k views

How to remove columns in a spatial polygon data frame in R?

My spatial polygon data frame (spdf) contains too many columns (variables) and I want to remove most of the columns entirely. I know how to do this with a regular data frame in R, but I am unsure how ...
4
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2answers
140 views

“Levelling” elevation data coinciding with polygon?

I have a shapefile containing building geometries (polygons) and a elevation dataset. The elevation data doesn't perfectly match the buildings. I want to "flatten" the elevation data so that ...
4
votes
2answers
4k views

How to Polygonize a polyline shapefile in QGIS 2.2?

When I used QGIS 1.8, I was able to transform polyline layers to polygon layers with the Polygonizer plugin. In QGIS 2.2, this function has been subsumed into the Processing toolbox. Unfortunately, ...
4
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1answer
782 views

How to give elevation information to a polygon feature class using existing TIN file ? (geological mapping)

I'm an ArcGIS 10.1 user. My issue: I have a printed form of a map which depicts geological bodies being surface rock occurence. Additionaly, there are elevation contour lines. I digitized the map by ...
4
votes
1answer
1k views

ArcMap 10.1 SP Spatial Join Problem (lines within polygon)

I have a line layer (faults) and a polygon layer (fishnet grid). The fishnet has a risk of earthquake attributed to each polygon. I want to take that risk value and give it to the fault lines which ...
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4answers
2k views

How to import polygons from OSM to QGIS?

I am trying to import Polygons from OSM to QGIS 2.0, but so far I have no idea how to do that. E. g.: Kisterseg auf Tatabanya in HU: http://www.openstreetmap.org/?relation=1027806 Is there any fast ...
4
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2answers
1k views

How do I find the average distance within a polygon to a point?

For my purposes, I can assume a homogeneous distribution of points within the polygon. What I want to find is the average distance from points within a polygon to a specified point. I don't know where ...
4
votes
1answer
346 views

Polygon to Raster taking longer in script than in ArcMap?

I have a large dataset that I am working with. Basically I have a table with 900,000 records that I join to a geodatabase feature layer, then convert that to a raster. This process takes a total of ...
4
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3answers
1k views

How to split features?

I would like to split a shapefile in qgis according to how the polygons overlaps. Don't know how to though? See pic for explanation:
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1answer
355 views

Validating polygons for no gaps/overlaps/slivers using ArcGIS Desktop?

I would like to assess the spatial accuracy of a load of polygon shapefiles which are supposed to show air quality for a bunch of countries. Firstly I want to assess whether each shapefile has a ...
4
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3answers
9k views

How can I calculate the center point inside a polygon in ArcGIS 9.3?

I'm using the JavaScript API 1.6 on ArcGIS 9.3. I have a polygon geometry in an ArcGIS map, and I'm trying to find a way to get the point that lies in the exact center of the geometry. What is the ...
4
votes
2answers
350 views

How to attribute lines with IDs of touching polygons?

I have two shapefiles: one contains streets of a city and one contains blocks (i.e. polygons bounded by the streets). I would like to have the streets attributed with the IDs of the left and right ...
4
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1answer
48 views

Edit polygon borders in QGIS preserving topological correctness (planar partition)

Given a layer of polygons that is topologically perfect, i.e., has no overlaps or gaps between the polygons, is it possible to manually edit the edges of the polygons in QGIS in a way that preserves ...
4
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2answers
79 views

How to find 2nd order polygon neighbors? (and 3rd, 4th etc.)

I have a shapefile of contiguous polygons and for each pair of polygons, I need to know how many polygons are between them, following an neighboring/bordering approach. The output is likely to be a ...
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1answer
50 views

PostGIS point distance from polygon not 0 when on edge

I have a pretty simple problem: SELECT * FROM ST_Distance(ST_GeographyFromText('POLYGON((70 -40,70 -39,71 -39,71 -40,70 -40))'), ST_GeographyFromText('POINT(70.48 -39)'), False) returns ...
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1answer
77 views

Weighting amount of overlapping polygons in postgis

I have two tables that I join in my existing workflow. One of these includes flood events (was a shapefile that has been imported to PostgreSQL), the other one is a grid that holds the amount of ...
4
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1answer
755 views

Shapefiles - Polygon type - is it in fact multipolygon?

I'm wondering about the ESRI shape file with shape type 5. When reading the spec I see that "A polygon may contain multiple outer rings.". Does this mean that these outer rings must be combined to ...
4
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1answer
426 views

intersection between two multipolygons yielding anomalous GeometryCollection object full of LineString's & Polygon's (trying to get intersect area)

Normally when I call the #intersection method on a multipolygon to find the intersection shape on another multipolygon I get a multipolygon returned back to me. Either that or something else I can ...