Process of creating geometric polygon features.

learn more… | top users | synonyms

4
votes
2answers
62 views

How do I create blocks from a road network?

I have a road network and for every enclosed area within the network I want to create a polygon that represents that area. How does one do this?
2
votes
2answers
414 views

Shapely MultiPolygon Construction - Will not accept the entire set of Polygons

I am new to Shapely, so I am using a work request to learn a bit more about it. I need to execute a number of unions to build larger geometries from assessment neighborhoods in DC. I am curious ...
2
votes
2answers
316 views

How do I create a polygon layer from multiple touching line segments in QGIS?

I'm trying to create a base map for a Maine Coastal area, and wanted to create a polygon layer of the land cover from the coastline in QGIS. Whether I created the coastline vector layer from the USGS ...
0
votes
0answers
120 views

How do I optimize the speed and enable ArcGIS to create the Service Area around my locations?

The Problem: Every time I try to solve the service area around locations, ArcGIS crashes. It takes forever to load facilities and draw just a single polygon. How do I optimize the speed and enable ...
3
votes
0answers
223 views

Postgis - extrude a polygon

I want to extrude a polygon shape in postgis to create a pseudo 3D effect. To this end I have written a crude function to achieve it. This is very much test code and it creates a new Y vertice for ...
1
vote
0answers
54 views

Collection of polygons from a collection of points

I have a set of points, spread over a wide geographical area. I need to be able to create a set of polygons which best represent the clustered points. And I would like to create the clusters based on ...
0
votes
2answers
264 views

st_multi equivalent in Oracle spatial / how to convert polygon to multipolygon?

is there an equivalent to the PostGIS ST_MULTI available in Oracle Spatial? or - How can I convert POLYGON to MULTIPOLYGON in Oracle spatial? Regards, D
1
vote
2answers
248 views

Automatically create polygons from top right and bottom left coordinates?

I have a CSV file with hundreds of records. Each record contains 2 matching coordinates, 1) top right corner of a rectangle, 2) bottom left corner of a rectangle. Polygon ID, Lat 1, Lat 2, ...
3
votes
3answers
1k views

Remove slivers from merged polygons

I am creating a single polygon by merging different polygons in ArcMap. When I merge them, slivers are created. So I have to delete those slivers manually. I don't have a license for ArcInfo so tools ...
1
vote
1answer
1k views

combine several polygon objects in one polygon object with geotools (is it possible)?

I have several polygon objects and I need to "merge (or combine or dissolve)" them toghether into one polygon object. With a GIS tool like Quantum GIS, I do this with Geoprocessing option "Combine ...
1
vote
0answers
453 views

Topography: How to convert raster into vector layers?

(nb:This project is part of the #Wikipedia #wikimaps project) 1. Question: How to create vector topographic maps from raster image ? How to convert raster topographic image into closed vector ...
2
votes
2answers
147 views

Tool for Creating Polygons

Does anyone know of any tools that exist for creating a polygons. I need to provide some employees with the ability to create shapes that detail the boundary of certain locations. So I just want a ...
0
votes
1answer
493 views

How to remove shapefile polygon vertex marker points in QGIS 1.8.0

I have created a shapefile layer and drawn a polygon to show the boundary of a woodland. How can I edit the polygon to remove the crosses that denote the intersection of two points on the boundary?
2
votes
1answer
76 views

POLYGON25D WITH OGR2OGR

I know how to convert a csv file with xyz coords to point25d with ogr2ogr and vrt file but the coords in the files are the vetices of 3dpolygon (firsth and last ones are the same coords). I want to ...
4
votes
1answer
246 views

How to generate overlapping polygons from lines output from Table To Ellipse tool?

I have a feature class of line-based ellipses generated by the Table to Ellipse tool that looks like this: What I want is polygons of the individual ellipses, however tools like Feature to Polygon ...
3
votes
2answers
2k views

Colouring areas between (vector) contours?

Is it possible to colour areas between (vector) contours without making it a DEM first? Joshdoe seems to have done so in Create filled contour map with GRASS but does not say how.
4
votes
1answer
736 views

create grid cells of fixed dimension around a point acting as a centroid

I've been trying to solve a problem for the last few days but not having much luck. I'm hoping someone here can point me in the right direction. I'm new to ArcGIS so I hope my explanation makes ...
3
votes
3answers
554 views

What Is The Ideal Workflow To Map (British) Postcode Territories

I'm looking for the best workflow for mapping postcodes and calculated territories, but being relatively new to mapping I'm struggling on a few details and also the best practices for displaying these ...
0
votes
0answers
128 views

How to draw polygons around known clusters

I need to split up an area into non-overlapping, but contiguous territories. I have n points on a map, which are partitioned into k sets. The partition is only partially geographic, meaning that ...
7
votes
2answers
195 views

Generating polygonal blocks using growing lines

We first generate a set of locations (i.e., points(x,y)), randomly. Then we assign for each point a number showing the angle of a line being centred at that point. The criteria for the length of lines ...
2
votes
1answer
206 views

How to make new polygon/feature from point which is NOT centroid?

I've spent all morning searching help sites and digging through the FAQs and worksheets but have failed miserably. I am an ArcGIS novice so I hope this is not too much of a "newbie" question but I'm ...
1
vote
0answers
159 views

Problems combining (union) Multipolygons in geodjango

I'm using geodjango and postgis (1.x), What is the best way to combine (union) a list of multipolygons. in what i assume is rather inefficient i'm looping trough like this combined = multipolygon ...
3
votes
0answers
200 views

building larger polygons from smaller ones *without* a common id in PostGIS

I am looking for a means, using PostGIS, of reconstituting a set of polygons from tens of thousands of smaller polygon 'pieces'. This is a simplified example, with the pieces shaded: Unfortunately ...
8
votes
3answers
932 views

How to apply the four colors theorem in a polygon map in ArcGIS/ArcToolBox automatcally?

I need to apply the four colors theorem in a polygonal shape in a way that I do not need to choose manually each color to put in each region. I wish to knows if there is any extension, plug-in, script ...
4
votes
2answers
463 views

How to create a smallest quadrilateral concave polygon around GPS points?

I have this GPS track in a metric grid (Symbology by elevation, if anyone wonders): I need to define it's general area - for registrations and permits, with just 4 points. Therefore, I assume that ...
2
votes
1answer
1k views

how to connect points to create a polygon boundary in QGIS

I have 31 points in a shapefile, which delimit a field (it's an irregular shape). I want to connect those points so they create the boundary of a polygon. Does anybody know a kind of "connect the ...
2
votes
1answer
346 views

Tearing in ggmap (R) after using spTransform and random point generation using splancs

I am using R and the package ggmap to try and generate some random points within the city limits of Chapel Hill, NC. I have downloaded the shapefile for the town of Chapel Hill from the Orange County ...
2
votes
1answer
586 views

Create a shapefile from geometry

Please excuse my lingo, I am still learning some aspects of geo spatial and arcpy. I have a python script that takes a shapefile. The shapefile consists of a polyline. I have traversed the polyline, ...
1
vote
4answers
602 views

How to create internal polygon without overlap on QGIS1.8.0

I would like to create new polygon inside the existing polygon. It does not means donuts polygon. I would like to have two polygon without overlapping. I can create if I don't check "Avoid ...
8
votes
1answer
882 views

Polygon creation (Clockwise rotation or not)

According to "ESRI Shapefile Technical Description An ESRI White Paper—July 1998", Vertices for a single, ringed polygon are, therefore,always in clockwise order. Otherwise,"Dirty" polygons occur when ...
1
vote
1answer
315 views

Displaying only points within a polygon I created in QGIS?

Thank you in advance for any advice you might give me. I am new to qgis and believe what I'm asking is probably fairly basic. I am trying to map policing activity in NYC for two areas: one area in the ...
7
votes
3answers
3k views

Extract Overlapping Polygon Data to Points

I have a polygon data set of corn yield collected by a combine. However, as the combine drove through the field, there was slight overlap between passes, leading to overlapping polygons within the ...
5
votes
1answer
380 views

Simplifying polygons made from binary rasters

I'm using MaxEnt to produce a species presence / absence raster layer. It works fine but I have to choose a cut off point for what constitutes presence or absence. As a result I end up with a lot of ...
5
votes
2answers
1k views

Why does this simple Python OGR code create an empty polygon?

Please excuse my ignorance...I am new to Python OGR. I am trying to create a simple square polygon and fail...this produces an empty polygon. Where did I go wrong? from osgeo import ogr driver = ...
2
votes
1answer
1k views

How to draw a polygon with preset length in OpenLayers?

For a project I am working on, I need to be able to put a polygon on a map using OpenLayers, based on a variable point that can be set by a user. The polygon is an isosceles triangle of which two legs ...
2
votes
2answers
1k views

Problem creating polygon features using ArcObjects / ArcGIS 10

I need to create a grid of polygons. Each polygon is rectangle, thus has 4 corners (vertices). When I create polygon features using ArcObjects they seem to have wrong geometry, which results in wrong ...
0
votes
1answer
120 views

Creating rectangle over a buffer circle with specified angles/rotation?

I have a layer that is a circle buffer around a point. What I want to do is create a rectangle around the circle, but have every rectangle be perfectly lined up N/S (0degrees of angle/rotation). I ...
8
votes
6answers
2k views

How to split a polygon into quadrants?

I have a Alberta province (Canada) section polygon shapefile in GCS_NAD83 with 255,000 polygons. I like to split each section into 4 equal quadrants (NW, NE, SW, SE) The Alberta province has ...
2
votes
1answer
1k views

Create new polygon layers from postcodes latitude & longitude

First at all, I want to say that I am geocoding enthusiastic but have no formal background on GIS. I'll do my best to use the right wording and make myself clear what I am striving for. Also the only ...
1
vote
1answer
4k views

Build Polygons from Polylines

I have to build the polygons from some polylines it is an area like a main land(with some boundaries) and some islands around it,islands are building polygons and main land is missing,when i have ...
2
votes
0answers
311 views

Right click editing menu disabled arcgis 10.0

Editing Polygon feature in FGDB, Create Features, Click Rectangle (in Construction tools), right click, unable to select any options (Absolute X, Y / Direction / Length) from popup menu. Help? Havn't ...
4
votes
1answer
1k views

How to programatically populate a shapefile field with polygon areas in OGR?

I'm trying to programatically populate a shp field with polygon areas: import sys import ogr ds = ogr.Open( 'tttttttttt.shp', update = 1 ) if ds is None: print "Open failed./n" sys.exit( 1 ...
1
vote
1answer
369 views

Polygonizer plugin for QGIS halts in Windows?

I've had some success and some problems using the Polygonizer plugin in the past. I'm using Polygonizer 2.1 in QGIS 1.8 on Windows 7. I'm aware there are sometimes problems using Polygonizer in ...
4
votes
2answers
2k views

How to draw polygons in QGIS perfectly aligned

I would like to draw polygons for an indoor map test and would like to draw perfect rectangles (horiz. and vertical edges). How to set QGIS options on polygon edit /draw to do that ? thank you for ...
3
votes
3answers
1k views

How to digitize polygons from georeferenced raster file

I used QGIS to georeference a raster file of a custom US map. The map has features which are not strictly defined by state borders. I would like to digitize the map by creating contiguous borders for ...
5
votes
2answers
166 views

Create polygon from page size

Is there an easy way to create a polygon that matches the data frame in my page layout? I'm trying to set up data driven pages and want to have it key off of polygons that frame the boundaries for ...
5
votes
1answer
703 views

Polar grids in ArcGIS

I am looking automate the creation of a polar grid shapefile (polygon). I am currently creating this in a many-step editing process, starting from a concentric buffer. Here is how I think I should be ...
0
votes
0answers
565 views

Why is a Shape polygon file not editable?

I received a .shp polygon file. When I choose the edit toggle tool in QGIS the little red X's appear as expected. Then when I try to edit the polygons such as add a polygon all seems to go well, when ...
2
votes
1answer
1k views

How to create a grid constrained within a polygon in QGIS?

In QGIS I have created an irregularly shaped polygon. I can create a grid based on the maximum extents of the polygon via Vector>Research Tools>Vector Grid. However, what if I need the grid to ...
4
votes
2answers
10k views

Create polygon layer from polyline layer

Our systems expect polygon shapefiles, representing a collection of non-intersecting and geometrically valid (multi)polygons. Specifically, farm fields. We often receive our representations of farms ...