Questions tagged [simplify]

A type of cartographic generalization in which the important characteristics of features are determined and unwanted detail is eliminated to retain clarity on a map whose scale has been reduced.

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1answer
40 views

Simplifying polygon edge while preserving minimum area and width [closed]

I am working with river buffer areas. The area that you see in the first picture is a 100-meter buffer of a polyline (a polyline isn't visible but it is there). I want to simplify the edge in a way, ...
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1answer
42 views

Holes after topology simplification

After applying the topology simplification mentioned in the answer Remove Slivers/Gaps generated after TopologyPreserveSimplification? It is retaining the topology but is removing the polygon. Below ...
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0answers
22 views

Lining up boundaries at corner of polygons

I have a polygon layer with the boundary of a lot of zones. The boundary of many of them skips at the intersection where multiple zones come together (shown as in the picture). I am trying to find out ...
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0answers
22 views

Polygon boundary not adjacent after simplification [duplicate]

I am simplifying set of polygons that are adjacent. I used topologypreserveSimplifier which simplify each polygon separately the issue is the resulting polygons are not adjacent anymore. After ...
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1answer
58 views

Remove Slivers/Gaps generated after TopologyPreserveSimplification?

I am trying to simplify my geometry using TopologySimplifier to simplify my shapefile , but after this I am getting so many sliver/gaps( even trying with different tolerance (.001 to .005). Below is ...
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1answer
68 views

Removing sharp curves using ArcPy

I have been trying for some time to find a way to eliminate the exaggerated curves in a contour curve that I usually obtain from line 0. The idea is to obtain a polyline that is more or less faithful ...
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5answers
315 views

Simplifying polygon by inner angle

I'm trying to simplify a polygon using the interior angle of a vertex as the "tolerance" instead of the distance between vertexes. E.g. the polygon in the image below would lose one vertex, ...
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1answer
77 views

Generalizing line with angle rules in QGIS

I'm looking for an automatic way to generalize/simplify vector lines in QGIS like the following picture : I would like the generalization to include only the angles indicated by the small star on the ...
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1answer
70 views

Is it possible in QGIS to simplify a vector layer forcing orthogonality (only 90º angles)?

I have tried different simplyfying algorithms and options within them (QGIS native, SAGA, GRASS) but nothing has worked. I saw there is an "Orthogonalize" tool in 3.x versions, but from what ...
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0answers
122 views

EPSG:3857 to 4326 - incorrect geometry

I need to get simplified boundaries of all countries with some buffer around them (20 km). I am using QGIS, I converted my country polygons vector layer from 4326 to 3857, set buffer, used simplify ...
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1answer
77 views

Making vector geometries "Kiss" in QGIS

I am working with vector geometries that I recently simplified using the native:simplifygeometries method in the processing toolbox. I am pleased with the simplification but I want to "fill" ...
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1answer
50 views

Shapefile simplification

Sorry for the lack of terminology as it escapes me. I have a shapefile that contains 96000 individual polygons and I'd like to simplify the shapefile so that it creates 1 polygon. I think it is ...
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1answer
106 views

In the QGIS error message "Feature (99) has invalid geometry" does the 99 refer to the OBJECTID?

QGIS 3.4.2-Madeira running simplify on a polygon z shapefile with 1075 rows. "Feature (99) has invalid geometry" not sure how to find this feature. If I edit and delete the row with OBJECTID ...
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0answers
67 views

Simplify/generalize vector geometry with side bias

I have contour polygons as vector geometry with attached elevation attributes. Is there a method to simplify vector polygons while preserving topology and elevation bias? By elevation bias I mean that ...
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0answers
76 views

Simplifying parts of polygons in QGIS

Is it possible to simplify just the selected parts of a polygon? I am trying to make a simplified version of the Australian Local Government Areas (LGAs) shapefile. I am using the v.generalise ...
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1answer
32 views

Simplify OS MasterMap Data without Losing Key Details

I am building a flood model (Infoworks ICM), using OS MasterMap Topography data supplied in shapefile format to define land use such as roads, buildings, fields etc across the river's catchment. The ...
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0answers
23 views

How to smooth interior polygons of one shapefile

I have a shapefile that includes the boundary of a field plus many interior polygons that represent levels of NDVI - we'll say High, Medium, and Low. The larger areas have jagged, irregular edges. ...
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3answers
227 views

Simplifying adjacent polygons on subset of vertices only

We have many adjacent polygons which are very complex and we need to simplify only some portions of them. There are no gaps nor overlaps between any two adjacent polygons. What we'd like to do is to ...
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1answer
250 views

BigQuery GIS table to GeoJSON type Feature Collection with SQL and/or Python

I have some BigQuery tables with spatial data (lon, lat, point, and linestring) representing boat tracks. I'm trying to get them into a GeoJSON featurecollection like [https://geojson.org/], for an ...
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1answer
280 views

Simplifying label geometry in QGIS

I have a bunch of linear data (trails) stored in PostGIS and visualized in QGIS for cartographic production. Many trails have switchbacks, and are generally very "weavy", which makes for difficult ...
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1answer
157 views

Simplified lines disappear in smaller zoom levels in ArcGIS JavaScript v.4.14 map

I have a GraphicsLayer on ArcGIS js map with many lines of varying lengths (1 to 200m). However, in smaller zoom levels the short lines disappear. For example, in the images below the red lines are ...
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1answer
90 views

How to check "simplification sensibility" of a geometry?

It is expected that a "geometry simplification" is a good practice to preserve stable versions of a geometry, avoiding minor and non-relevant changes (side effect of geometry-editors and other "false ...
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0answers
56 views

Problem when using Simplify Tool in QGIS

I want to simplify district borders. As I got bad results when using polygons I converted those polygons into lines but I still have the same problem that I get new vertexes or corners I don't want. ...
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0answers
157 views

Simplify line in QGIS

I have very long curvey line which I want to smplify. I have used the simplify tool on QGIS but it is still not simplified enough. Tgose are the parameters I have used: The thing is that I still have ...
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3answers
111 views

Generalising lines of varying detail in QGIS

I am trying to generalise a line in QGIS so that I can export it as a vector without it having an unnecessarily huge file size. The line shows the GPS track of a road trip, and as such varies between ...
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2answers
193 views

Can't simplify track with gpsbabel

I have a MultiLinesString layer in a geopackage that I want to import to a Garmin GPS as a track. I exported the layer from QGIS as a .gdb. However, it's too long to import to the GPS (~2500 points, ...
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1answer
167 views

Original polygon is completely contained by new after simplifying

Is there a polygon simplification method that can create a polygon, such that the original is completely contained by the new one? The aim is to create the new polygon from as few points as possible ...
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1answer
275 views

Wang's Bend Simplify in QGIS

I am looking for an alternative to ESRI's Simplify Polygons - Bend Simplify method (I only have a Basic License). Is there an existing QGIS plugin which supports this specific polygon simplifying ...
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2answers
491 views

Reducing coordinate decimal places in WKT using C#?

I have imported several shapefiles into a Microsoft SQL Server 2017 database When I use the STAsText() function on geography objects I get the following WKT: SELECT [Adm0GeoBoundaryID] ,[...
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1answer
46 views

Simplify Slider

QGIS 3.4 appeared to have a slider for adjusting the simplification tolerance - at least that is what shows up in the 3.4 documentation, for example: https://docs.qgis.org/3.4/en/docs/training_manual/...
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0answers
74 views

Simplifying Multiple neighbouring Polygons, removing gaps and overlaps

My main goal is to simplify multiple polygons, avoiding overlaps and gaps between them. My initial approach was: Find intersections for each polygon so that I end up with an array of polygons, each ...
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0answers
3k views

Geopandas simplify results in gaps between polygons

The goal is to simplify the geometries of a shapefile containing multipolygons. However, when I use Shapely's simplify in geopandas, the result contains gaps between the polygons. I was hoping that ...
3
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0answers
190 views

Generalizing / simplifying multipolygon in PostGIS without missing polygons?

By following the rules from this site, I got the output but some polygons do not come within the simplified polygon. I think the problem is with topology. Is there any solution?
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1answer
177 views

"Average" of two lines

I have a dataset of pairs of parallel linear features (railway tracks) and I need to simplify each pair into its central/median line. This could be achieved by computing a skeleton as suggested in ...
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2answers
948 views

Simplifying multiple lines to create central axis?

I have a layer with railway lines, downloaded from OpenStreetMap. Every single track is represented separately, so at trainstations, you have several parallel lines, as well as sidelines that lead to ...
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0answers
70 views

Convex boundary of polygon [closed]

Is there any tool that can help me with my problem? I have polygons looking like this : And what I want, is to simplify or gain convex boundary of such polygons. I tried Simplify Polygon in ArcMap, ...
3
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1answer
967 views

PostGIS snap line segment endpoint to closest other line segment

I have a PostGIS table of singlepart line segments that I've run the ST_ChaikinSmoothing function on. Smoothing all of the line segments worked great, but these simplified geometries created small ...
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2answers
524 views

Reduce complexity of KML file

I have a 6mb KML file I am using with the Leaflet API/Ominvore plugin. It is just a centerline of a long distance trail. What would be the best way to make it smaller? Reduce complexity etc.
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0answers
77 views

How to remove narrow 'notches' in polygons?

I am currently working on a project where i am doing a union on several feature classes. The union normally creates several polygons which share edges/borders. however after running dissolve on the ...
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2answers
324 views

Simplify a circle into square with SF

I want to obtain a square from a circle using simplification function in sf. This is my circle: With this code, I obtain a rhombus plot(st_simplify(st_geometry(sfdf),dTolerance = 1000)) How can I ...
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2answers
1k views

QGIS remove useless vertex to simplify polygon

I received a shapefile which is the result of a combination of several polygon. I want to clean and simplify it as there are many useless vertex as you can see on the picture. This is only one feature ...
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1answer
67 views

Remove small interstices on the edges of a polygone

How can I remove the white interstices on the edges (and interior) of a polygone or polyline, as represented in the first figure below? I want to get smooth and continuous edges, capturing the global ...
3
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1answer
1k views

Simplify geometry

Which is the best way to convert a complex multipolygon into simple and "merged" polygon? For example, the red stroked polygon (drawn by hand of course) is the simplified version of the white ...
3
votes
1answer
847 views

How to delete from mutipolygons all but the biggest polygon in QGIS

I have a bit too complex multipolygon set to be used in a web application (thematic map) so I'd like to simplify the structure by removing small islands of areas. I am not an expert on QGIS but so far ...
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1answer
227 views

Aggregating geometry features on geometry simplification using PostGIS?

PostGIS has ST_Simplify functionality which gets one multiline as input and returns one output multiline where the general shape of lines are retained while eliminating unnecessary detail. Instead of ...
2
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0answers
327 views

Building footprint polygon simplification / generalisation

I'm looking for implementations of polygon simplification algorithms that preserve topology and overall rectilinearity. The input data is building footprints which often have squarish protrusions and ...
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1answer
56 views

Reducing filesize for landslide susceptibility map

I have a large .tif file that I would like to reduce to under 15MB (currently 650MB). The file shows 3 zones of landslide susceptibility (see pic below). I am processing it so that I can upload it to ...
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0answers
18 views

What simplifying polygons functions f y = f(x) have ( y union x equal y ) property?

I've looked at GRASS v.generalize manual but they don't say. As far I can tell there's hermit but it's a Smoothing function.
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0answers
724 views

producing smooth iso polygons from raster surface? [closed]

The objective is to turn a raster surface (double value type) into smooth, visually appealing polygons representing iso-levels. I cannot stress enough that these must be visually attractive. Jaggedy ...
2
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1answer
406 views

Simplify Geometries 'NoneType' Error in QGIS

I need to simplify the geometries of a large amount of polygons, yet every time I run the Simplify Geometries tool in QGIS, I get the error message below. 'NoneType' object has no attribute 'type' ...