Questions tagged [dissolve]

To merge features based on specified attributes.

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214 views

How do I select the longest connected lines from PostGIS ST_ApproximateMedialAxis?

I used PostGIS ST_ApproximateMedialAxis to transform polygons representing mountain ranges into a series of lines. Now, I'd like to select only the "longest" line segment for each group, so that I ...
3
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0answers
339 views

Dissolve fails, geometry errors, and cleaning problems

I fairly new to GIS, and I'm having an issue with dissolving a vector. To start, I'm running QGIS 2.14.15 on Windows 7 Pro. When I try to dissolve the polygons it creates a blank shapefile. All of the ...
3
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0answers
56 views

After dissolving lines, old node/vertex order does not reset, causing issues with chainage

In QGIS, I am trying to dissolve multiple segments of a river feature and then calculate chainage on the resulting single feature. However, it seems like the internal node/vertex order gets preserved ...
3
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1answer
283 views

How to dissolve by two fields using C#

I need to dissolve a feature class based on two fields for the dissolve_field parameter and two fields for the statistics_fields parameter. Does anyone have an example of how to do this using C#? ...
3
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0answers
161 views

QGIS Dissolve skips polygons

I'm having trouble with the dissolve function in QGIS. Is it because of an overlap? It's not a GRASS layer, just shapefiles. I'm new with GIS software in general. Searched for similar problems but ...
3
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0answers
629 views

Dissolving polygons in a large dataset

I need to dissolve polygons by the ID attribute in a large dataset (+-1gb shapefile). I have been struggling to find an efficient method to do this. I have tried the following methods: Postgis ...
3
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0answers
543 views

QGIS/GeoJSON: Dissolve featurecollection consisting of polygons and multipolygons into a large multipolygon

I've read this question. I would like to know how to do this in QGIS. I have a Geojson file with a featurecollection, starting with: {"type":"FeatureCollection","features":[{"type":"Feature","...
2
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0answers
33 views

Preventing gaps on polygon shapefile being filled automatically when exporting from QGIS?

I classified raster dataset and converted raster dataset into polygon shapefile, then merged adjacent grid polygons using QGIS Dissolve function (figure 1) creating a temporary file. However, when I ...
2
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1answer
47 views

QGIS (merging, dissolve, union) lines of same name

I have street data where roads are segmented for no particular reason. I want to merge, dissolve or union whatever seems fit to make a single flat line. I H have tried above processes in QGIS but ...
2
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0answers
81 views

Dissolve Line Strings to one string - “No Shapely geometry can be created from null value”

I have a layer with 7000 LineStrings, all represent bus routes: It seems that all the bus routes are contiguous, but I'm not sure of it. I'm trying to use python shapely to dissolve all those ...
2
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0answers
49 views

Arcpy Dissolve creating grid that is not produced when run manually via ArcMap

Software: ArcMap 10.5.1, ArcPy I have created 2 python scripts that seeks to create a floodplain polygon from a DEM. py1 is DEM to Polygon while py2 cleans polygon to create final output. In py2 ...
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0answers
48 views

Dissolve field while preserving another related field

I am using 'Store' as dissolve field and 'Profit' as statistics field with statistic type 'MAX', and would like to preserve the related 'Fruit'. This is my original table: ...
2
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0answers
188 views

Calculating combined area of multiple polygons by counting overlapping area only once in R?

I'm using a shapefile in which polygons represent the geographic distribution of species. I need to calculate the combined range of several species sets, but the overlapping areas should be counted ...
2
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0answers
272 views

geopandas dissolve versus postGIS postgresql aggregated groupby dissolve

I have a geodataframe for which I want to dissolve the geometry based on an attribute (fao_id). In geopandas this is easy as gdf.dissolve(by="fao_id", aggfunc="first") but unfortunately this fails due ...
2
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0answers
44 views

Dissolve in QGIS to merge several processes in different regions into one process with all values

I am working on a dataset where I combined geographical information of cities in Europe and changes of landcover in these regions. I am working with the CORINE Dataset and I would like to know about ...
2
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0answers
48 views

Dissolving polygons based on spectral differences from QGIS?

I'm looking for a package or algorithm that allows to dissolve polygons based on their spectral characteristics and a threshold defined by the user in QGIS. Equivalent to what the "Spectral ...
2
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0answers
639 views

PostGIS: ST_Union fails with valid polygons?

I am working with this dataset. I have imported it into a Postgres 9.6 database with shp2pgsql as follows: shp2pgsql -I -s 5070:5070 us_govt/PADUS1_4Fee.shp usgovt | psql -d mydb I have made all the ...
2
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0answers
299 views

QGIS Dissolve running out of memory

I have data about the basic municipality areas of Mexico in a shapefile. I also have data about which metro areas they correspond to (csv). I would like to dissolve them -or so I understand from ...
2
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0answers
345 views

PostGis - st_union polygons, keep sum of attribute

There are multiple My current query is: SELECT (ST_Dump( ST_Union( way ) )).geom AS way, 10000 AS way_pixels FROM ( SELECT way, way_pixels, ...
2
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0answers
319 views

Dissolving polygons using SAGA leaves gaps?

I am new in using GIS and I'm having some problems in properly dissolving some polygons. In particular, I have a single layer with about 3,000 polygons (protected areas), some of which overlap (the ...
2
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0answers
17 views

How to create one attribute containing multiple adjacent parcels?

I'm trying to upload town parcel data to my Garmin GPS from Esri. Garmin registers each attribute as an entirely different file, and requires you to 'turn on' each file to display it on the GPS. This ...
2
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0answers
240 views

Dissolving polygons with common attribute within certain proximity to each other using QGIS?

I have a land parcel with a lot of polygons with the same attribute (owners). I would like to dissolve all the polygons with the same owners but only if the polygons are within 100m of each other. How ...
2
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0answers
111 views

How to union linestring data distributed on multiple layers?

I have four shapefiles. Each contains a linestring as shown in the image. Each shapefile is represented as its own layer in QGIS. I would like to union these linestrings into one polygon which ...
2
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0answers
54 views

ArcGIS dissolve analysis output issues in geoserver wfs/ PostGIS

I have an ArcGIS dissolve analysis output (parcel data) that needs to be loaded on PostGIS and published as a wfs from geoserver. The issue is that the ArcGIS dissolve output shapefile, although can ...
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0answers
1k views

How to calculate Median of a table field in the Dissolve Tool of ArcGIS?

The Dissolve Tool of ArcGIS 10.0 has some statistical parameters as a type of calculation new values of each field in a process of dissolving of identical parameters . It has SUM, MAX, MIN, RANGE, ...
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0answers
145 views

Dissolve Statistics Fields and Statistic Type as Parameters in GeoProcessor

I have a published service which uses a dissolve. In arcMap the I get prompted for all the fields, including statistics fields and stat type. I have the statistics fields marked as parameters. ...
2
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0answers
117 views

Determining homogenous blocks of individual tree species in a woodland, and creating a new shapefile without blocks/polygons of < minimum area?

I'm working on a project attempting to identify suitable woodland habitat for red squirrel translocation wherein conservation efforts could be focused. Below is a small section of the map showing ...
2
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0answers
343 views

How can I merge postcode sector polygons into larger territories in QGIS?

I'm new to GIS so patience might be required :-) I'm building a basic web-based mapping tool for business use, to be used as a demo to show that we need one but managers don't know it yet! So far I'...
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0answers
23 views

Adding attributes from surrounding feature (exclave problem)?

Here is the problem: I am creating polygons based on the result of closest facility tool in Arcmap. Polygons consist of municipalities with the same closest hospital (impedance is a travel time, not ...
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0answers
34 views

Use of QGIS/GRASS/SAGA procedures on Geometry Generator

Im new at QGIS, started 2 weeks ago. I'm trying to automatize the display of a map and get rid of some "duplicated" layers and all the extra work. I need to know if SAGA's dissolve can be used in the ...
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0answers
36 views

Merging adjacent polygons using Geopandas by avoiding filling gaps

I have raster dataset that I would like to convert into vector polygons. Raster to polygon conversion works pretty good. But, having problem when I try to merge adjacent polygons using Dissolve ...
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0answers
22 views

QGIS dissolve/merge features by all attributes

I have a vector layer with thousands of features and over ten columns (attributes). I would like to dissolve/merge features with identical attribute combinations and keep the attributes. I think it ...
1
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0answers
41 views

Fill in gaps in QGIS shapes?

So basically, I've written a script that generates a lot of polygons over the UK with certain criteria. The output it a lot of shapes like the following - I wanted to know if, in QGIS, I'm able to ...
1
vote
1answer
63 views

Problems with dissolving layers [QGiS 3.4.1]

I am currently working on a set of data that defines restricted areas for use of photovoltaic modules. This set of data amounts to 270.00 polygons in total [with their own geometry]. For simpler ...
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0answers
65 views

QGIS 2.18.28 Dissolve Error: “-2147483645 See log for more details”

I am doing property research on a county in Texas. I have all the parcel data and am trying to dissolve by Owner Name so that I can use the info tool to quickly see all the properties a given person ...
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0answers
60 views

Unary union/Dissolve returns null geometry in QGIS 3

I am writing a python processing script in QGIS 3. In it, I have polygon geometry objects stored in a list polygonGeoms and I want to dissolve all of it into one geometry. However, when calling the ...
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0answers
18 views

Dissolve on attribute field and location?

I've got a county parcel shapefile and I'm wanting to find all the properties over 300 acres. When I dissolve based on ownership and search for dissolved properties that sum over 300 acres, some of ...
1
vote
1answer
132 views

Merge connected lines and split them after set unequal distances

I need to edit line features in QGIS 3.4.4. I have more than 1000 line features that I want to first merge and then split. The line features describe roads in useless intervals, my goal is to ...
1
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0answers
196 views

QGIS: Dissolving Polygons with Self-Intersection

I have created multiple polygons with some subset of track-lines, with the order of time those points were recorded. Therefore some of the polygons have self-intersection within the polygon. Is there ...
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0answers
59 views

Promoting to multipart using PyQGIS?

I am creating a code that aggregates neighbouring polygons if they have similar value on the field 'DN' and if they are closer than 50 m.Then I want to iterate this 3 times. I could already get the ...
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0answers
40 views

Summarize table by group and add logic to keep data

I need to dissolve a polygon layer by group but, at the same time, I need to keep some of the data in extra columns. This is the diagram: This is the logic for the new group: Cod = "Cod" where N1 ...
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0answers
273 views

Dissolve with stats plugin does not appear in QGIS 3.0

So far we have tried to: find it in the plugin repository from QGIS, with no luck. install the plugin downloading it from the web QGIS Python Plugins Repository: https://plugins.qgis.org/plugins/...
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0answers
21 views

Merging lots of small portions of line to longer adjacent lines using ArcMap?

I have a hydrologic system split into 100 meter segments which is what I'm looking for, but I also have a lot of very small segments all over my system. Is it possible to dissolve/merge those small ...
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0answers
50 views

Merging small lines to form longer line in ArcGIS Desktop?

I'm having some trouble with the dissolve tool in arcgis. I have a stream network that has some streams made up of a number of little segment that I would like to transform so that all the stream ...
1
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0answers
155 views

Dissolve polygons with road network gaps

I am using QGIS and have a shapefile of the blocks in a large city, where each polygon is a particular streetblock. The city is divided into various sectors, and each block has information on its ...
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0answers
59 views

Using Intersect and dissolve to divide district into certain regions with data of interest without losing spatial data in ArcGIS Desktop?

I am using an intersect/dissolve feature workaround in ArcGIS Desktop 10.5. I have a layer of districts of a city and another layer of parks in the whole city /layer of noise amount around big ...
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0answers
19 views

Finding parcels which combine to create largest area

I have a shapefile of 500 polygons and I need to find the 22 neighboring polygons that when combined will produce the largest continuous area. Does this involve the Dissolve tool? What do I ...
1
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0answers
762 views

Dissolving complex polygons using PyQGIS?

I have a workflow to eliminate small polygons within a layer and merge them with adjacent polygons. My input is the result of a polygonization of a raster (has no overlaps) and it has one field "class"...
1
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0answers
268 views

How do I remove the boundaries between municipalities of my shapefile?

I have a shapefile of a province right now. It includes the barangay/village boundaries and municipal boundaries. However, I only need the municipal boundaries. How will I remove the barangay/village ...
1
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0answers
88 views

SQL trigger that dissolves feature class based on multilabel fields

I am about write an SQL trigger which dissolves a feature class based on 5 fields, I used to do this using dissolve tool in the Arcmap as the following screenshots: Now, I need this process to be ...