The process of producing a polygon feature layer from a raster or from lines.

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1answer
18 views

How to polygonize using GeoDjango and PostGIS?

The code of GeoDjango-1.9.2 contains reference to the function ST_Polygonize at: https://github.com/django/django/blob/master/django/contrib/gis/db/backends/postgis/operations.py#L132 But is it seems ...
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1answer
108 views

Does CartoDB automatically fill in Polygon data for city/state? How?

I'd like to upload a spreadsheet that has custom city/state information and have CartoDB automatically fill in the polygon data - is this possible? If so, how?
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1answer
80 views

How to crop a vector shapefile according to raster?

I am trying to clip a vector shapefile- points according to a DEM in QGIS. I used GDAL function and polygonized the DEM. Then I ran the Vector-Geoprocessing tools-clip in order to crop the vector data ...
5
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98 views

Diminishing performance of gdal_polygonize in a python subprocess for GRASS to PostgreSQL

I have written a python script to polygonize GRASS rasters into a PostgreSQL database using the gdal utility gdal_polygonize: sub.call('gdal_polygonize.py -8 gdb/quercus/{0}/cellhd/{1} -f ...
5
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0answers
137 views

Why doesn't Polygonizer copy the line ids to my polygonized shapefile?

I am trying to convert a line shapefile into a polygon shapefile using Polygonizer plugin, and when my new polygons are created all the cells in my id field are "Null", although I have clicked "copy ...
2
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0answers
106 views

how to orthogonalize building outlines

I'm looking for a way to orthogonalize building outlines which I've extracted from a high-res DEM. I'm using the FOSS GIS stack (QGIS, GRASS, SAGA, PostgrSQL, PostGIS) and can code in Python (or ...
2
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0answers
128 views

QGIS polygonize GDAL DLL load failed

I'm using QGIS 2.6.1 and i've been having problems using the polygonize function. I keep getting a "DLL load failed" import error. I've searched older threads which unfortunately weren't able to ...
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55 views

Error in polygonising raster data with QGIS on Mac

I'm using QGis Chugiak on a Mac and I'm trying to converting a raster layer in a vector data by: Raster/Conversion/Polygonize. So, I select the layer needed from the drop-down menu, I give a name to ...
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50 views

How to specify a polygon face toward to different lines

I have a parcel layer, a street of city layer, I want to find the parcels at the corner of two different street (mean a house with two face toward to 2 streets) I appreciate your suggestion for ...
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246 views

Convert a classification image to aggregated polygon in shapefile using gdal/python

My goal is convert a 2D numpy array to shapefile. The matrix results from a classification, so the numbers have a meaning. I solved my problem, but the solution is somehow involuted and complicated. ...
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0answers
29 views

polygonize raster so that every cell becomes a polygon?

Is there a proper way of polygonizing a continuous raster so that every cell becomes a polygon? What I do now is make the cells differ enough so that the algorithm makes different polygons of them. ...
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106 views

python script in QGis - help using gdal.Polygonize

I want to create a very simple script in python that polygonizes a raster. Based on python cookbook + forums search I wrote the following code #import des modules from osgeo import gdal, ogr from ...
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78 views

QGIS Polygonize (GDAL) problem - Null value in attribute

Is it possible to use Polygonize in QGIS (GDAL) so that a line shapefile is converted to a polygon shapefile with an attribute(s) in the line file carried into the polygon file. I am trying to build ...
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0answers
814 views

Polygon of Voronoi cell using scipy.spatial?

I have points (e.g., lat, lon pairs of cell tower locations) and I need to get the polygon of the Voronoi cells they form. from scipy.spatial import Voronoi tower = [[ 24.686 , 46.7081], [ ...
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150 views

Error running polygonize from QGIS!

I'm trying to vectorize a raster image and when I'm running polygonize within QGIS 2.6.1. I'm getting the following message: Traceback (most recent call last): File ...
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0answers
91 views

Geoserver does not render polygon properly

I am trying to a get polygon layer from CSV file. I chose to do it via rasterization and polygonization in QGIS, howerver, Geoserver has problems to correctly render some polygons. This is how the ...
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87 views

Extract polygons of PNG with GdalOgrInJava

I have PNG pictures with polygons of different colours on them. What I plan to do is to extract these Polygons using the polygonize function (see here) Then I will try to encode the polygons in ...
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0answers
57 views

Polygonize Missing Polygons

Polygonize is not capturing all of the pixels in an image that has been converted to 0s & 1s. The pics below show -original geotif -geotif recalculated to 0s & 1s -polygonize output As the ...
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636 views

Line to Polygon via Polygonizer in QGIS

My question is in the same vein as this one. I'm attempting to convert precipitation lines (Precipitación Media Anual) to a polygon for Mexico in QGIS using the Polygonizer plugin. After running the ...
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83 views

Gdal Polygonize Java

I tried to use the gdalPolygonize function within in java. What I did Installed gdal-111-1800-x64-core from the following link ...
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0answers
32 views

polygonize some raster pixels based on their value in PostGIS

I need to extract and polygonize only those pixels of a raster that have a value (e.g.) greather than 2000.0 The reason is that I wish to do an operation like the following one (which is done only on ...
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163 views

Polygonize only pixel values of 1 from a raster

I have a raster mask that I have created in QGIS (2.2.0) that consist of 0, 1 and nodata values. I would like to end up with a polygon dataset that consist of only the value of one pixels from this ...
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203 views

QGIS GDAL polygonize - how to set scale

I've got some old contour plots, paper copy only, that I'd like to be able to put into QGIS. I get as far as a successful polygonize into shp and it looks fine, but the scale is wrong. How might I ...