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

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1answer
23 views

It is possible to get single polygon using gdal.Polygonize()?

I have to get polygon outline for all raster in our server. I tried one example raster and used gdal.Polygonize() function. With that I could produce thousands of small polygons but I only want a big ...
1
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1answer
44 views

gdal_polygonize returns with a strange error

i'm trying to execute gdal_polygoinize.py command. I have a main python method that takes in input a raster file and a output shapefile, and then calls a method named polygonize.py that builds and try ...
5
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4answers
199 views

How to speed up raster to polygon conversion in R?

I've decided to process my Landsat data in R instead or ArcGIS - due to my missing knowledge of python and and because of (assumed) high computation capacities of R. I want to : import r1 raster to ...
3
votes
3answers
84 views

DEM polygonize (raster to vector) doesn't work for contour lines less than 1 meter apart? (QGIS)

I tried to make polygon from DEM (geotiff) in QGIS. My requirement is that elevation value was every 0.5m of polygon. If I use the function polygonize (raster to vector) , polygon is created but ...
3
votes
1answer
64 views

OSM roads polygonized in PostGIS = nonsense

I have a dump of OSM data in my city and wrote a query to polygonize it. In the first attempt, the result looked like this: The problem was that OSM lines were not split and I guessed that the ...
1
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2answers
180 views

How to polygonize raster to shapely polygons

I am seeking an open-source python solution to convert raster to polygon (no ArcPy). I did know the GDAL function to convert raster to polygon, and here is the manual: http://pcjericks.github.io/py-...
2
votes
1answer
70 views

Polygons between contour lines in QGIS?

I am trying to create polygons between contour polylines within a defined area (for which i have both polygon and polyline shps) but I seem to be thwarted at every turn. Using QGIS 2.14, I am sure it ...
2
votes
1answer
28 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 ...
0
votes
1answer
159 views

C/C++/C# Library for raster to vector conversion

I am looking for an "open source" C/C++/C# Library able to convert raster to vector data (Polygonize). I know gdal_polygonize.py is doing the job, but I can't use Python. Portrace is an other option, ...
3
votes
1answer
86 views

QGIS 2.12 Lines to Polygons not work properly

In QGIS 2.12.3 I have a small shapefile with lines (as often occurs in parcel boundary datasets) of 2 vertices each, snapped to each other (no topology errors, no dangles, no intersections). But the "...
1
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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. ...
1
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1answer
42 views

Create kml from binary raster

I have a binary raster (values - 0 & 1) - I want to create a shapefile (KML for use in Google Earth) of the white area only (value = 1). Is there a simple method to do this?
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0answers
170 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 ...
1
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1answer
33 views

How can I make a polygon from intersecting lines of different layers in QGIS?

I am constructing a geological map which involves constructing boundaries to areas which vary in style across their length depending on how well defined they. To do this I have created two distinct ...
1
vote
1answer
145 views

Creating polygons representing specific range of values within raster using QGIS?

Using QGIS, I started with LIDAR points (every 5 m) on a 90’000 ha area and then converted it in a raster of elevation (interpolating to fill some holes in LIDAR data). Now, I want to get a polygon ...
1
vote
1answer
74 views

Creating Polygon from a Raster

I have a Raster representing climate data. I converted the raster to vector using the tool raster to vector (Arc Map) and i got something like below: Can somebody help me out by guiding me in actual ...
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3answers
135 views

OSGeo4W GDAL Polygonize Batch Convert?

I'm trying to use GDAL polygonize to run a batch convert but I cannot for the life of my figure out a way to get it to read a text file as input that contains all of the commands. Do any of you know ...
2
votes
0answers
124 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 Java)....
8
votes
1answer
207 views

Building a polygon over a reachable area

I am currently working in the field of isochrones and the underlying algorithms. What now causes problems is not the calculation if the isochrone itself, but the visualization of the results. The ...
1
vote
1answer
161 views

Trouble using gdal utilities in python (no output files created)

I am trying to use gdal utilities like gdal_polygonize in python to polygonize my raster image but I'm having trouble understanding the commands. What I mean is in some places the command is of the ...
4
votes
1answer
235 views

Raster to vector (polygons) with generalisation

I have created rasters showing different types of vegetation (bushes, trees, open land) with help from lidar data. Now I'm looking for a method to turn these images into polygons. I'm using a Mac ...
1
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1answer
75 views

gdal_polygonize with World File

I have this image that I want to convert it to GeoJSON. And I have this World File: 0.0388048118 0.0 0.0 -0.0387897595 697054.11331 4458020.56656 When I try to run the gdal_polygonize command ...
0
votes
1answer
107 views

polygonize giving duplicated polygons

I am trying to reproject some ascii files and convert them into shapefiles. I am new to python but looking at some code online and help files I was able to write the following code to run on Python ...
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0answers
94 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
964 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], [ ...
0
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1answer
172 views

Usage of gdal.Polygonize(,,,)

I am trying to code gdal_polygonize source.png -f "GeoJSON" destination.geojson with the java-bindings of gdal. I don't know how to make gdal.Polygonize(...) create the "DN"-Fields one obtains when ...
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0answers
26 views

gdal_polygonize floating values [duplicate]

gdal_polygonize converts whatever rasters values into vector integers as it is based on the GDALPolygonize() function (http://gdal.org/gdal__alg_8h.html#a3f522a9035d3512b5d414fb4752671b1). It is ...
0
votes
1answer
49 views

Code of _gdal.pyd

I want a deeper understanding of how gdal_polygonize.py works. It uses gdal.Polygonize and gdal.Polygonize refers to _gdal.pyd. Where can I see the actual algorithm where the actual polygonization ...
0
votes
1answer
76 views

Is gdal_polygonizer creating a wrong geojson?

I have this PNG and I use gdal_polygonize 0VxOhek.png -f "geojson" 0VxOhek.geojson This is the output. There is a "features"-array which contains many objects with "type", "properties" and "geometry" ...
1
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1answer
219 views

gdal_polygonize ignores some polygons

I want to polygonize this PNG. I try gdal_polygonize pic.png -f "GeoJSON" polygonized.geojson but I get only 11 polygons instead of more than 20. What is the cause or how can I fix it?
2
votes
0answers
141 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 help....
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0answers
164 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 "C:\PROGRA~1\QGISBR~1\bin\...
2
votes
1answer
158 views

Problem or ERROR in converting from raster to vector!

I wonder if anyone could help me out, i am kind of a beginner at QGIS. I´ve built a DEM for a project that i am developing than i´ve made the slope raster with the terrain analysis,it seemed that ...
1
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0answers
103 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 ...
2
votes
1answer
211 views

Which algorithm does gdal_polygonize use?

I would like to know which algorithm (i.e. Sobel operator ) is used to extract the polygons in gdal_polygonizer. I searched here and here but could not find it. Any help would be appreciated.
5
votes
0answers
107 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 "PostgreSQL\...
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0answers
90 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 ...
1
vote
1answer
118 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?
1
vote
1answer
133 views

Converting rasters to polygons through cell centers

With arcgis, it is possible to convert a raster image to a polygon representing the boundary of the raster using the Raster To Polygon tool. The output polygon will follow the cell edges of the ...
1
vote
1answer
3k views

qgis polygonize error 4 “file does not exist in the file system”

When I try to convert a raster DEM (in asc or geotif format) to polygons I get the error below. ERROR 4: `Y:/GIS/oversvmmelser/tmp/out.tif' does not exist in the file system, and is not recognised ...
2
votes
1answer
389 views

QGIS show gdal_polygonized file in EPSG:54004 instead of EPSG:3857

I am polygonizing a TIFF with the gdal_polygonize.py and the resulting Shape is shown in QGIS in the wrong projection - EPSG:54004 instead of EPSG:3857. I have a TIFF in EPSG:3857 and polygonize it ...
2
votes
0answers
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 ...
0
votes
1answer
91 views

Defining areas for inclusion in polygon conversion using ArcGIS for Desktop?

Using ArcGIS 10.2 for Desktop, I am trying to create a polygon shape(s) from a raster image. Is there a way to indicate areas I do not want included in the shape. Similar to a buffer I suppose, but ...
1
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1answer
86 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 ...
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0answers
60 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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0answers
182 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 ...
2
votes
1answer
345 views

How to split Polygons by line grid?

I want to split a polygon by a intersecting line into different parts, exactly like in this post(Qgis - Is there a way to split a polygon layer with a line layer?). I have a vector grid to cut the ...
0
votes
1answer
167 views

How to convert boundaries in image to polygons in QGIS

I have an image from a cities districts and their boundaries and I need them as polygons in QGIS. I tried "Raster -> Conversion -> Polygonize (Raster to vector)" as described here, but that ...
0
votes
1answer
354 views

How to colour contour lines in .shp file when the lines are not meeting in QGIS?

I am doing bathymetry analysis, where I would like to color the contours one by one in the case land is rising (or sea level going down). There is a comprehensive explanation about coloring contours (...
0
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1answer
200 views

Polygonize a raster using GDAL JAVA bindings - passing raster pixel value to the resulting feature

I have a raster GeoTIFF file with values from 0 to let's say 5. When I run gdal.polygonize (I'm working with JAVA and GDAL bindings to JAVA) on it, I get features with corresponding polygons. The ...