Skip to main content

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.

Filter by
Sorted by
Tagged with
-1 votes
0 answers
62 views

How do I separate and remove unwanted shapes from a linestring representing road data in QGIS?

I’ve simplified some GeoJSON data to use on a Garmin device, however the simplification affected junctions and interchanges, which created some undesired shapes, unfortunately no attributes were ...
IceBear123's user avatar
0 votes
1 answer
97 views

Simplify multipolygon in Google Earth Engine

I am working on Google Earth Engine and trying to simplify a multipolygon by first reducing its vertices and then removing unnecessary polygons that have fewer than 5 vertices. var gaul = ee....
Faisal's user avatar
  • 3
0 votes
0 answers
36 views

Transform the detailed vector layer in screenshot 1 into the simpler layer of screenshot 2

I have created a "detailed" vector layer of buildings from OS's VectorMap District data, styled with deprivation data (much like screenshot 1). I would like to create a simplified layer from ...
Turning-Century's user avatar
0 votes
1 answer
92 views

Simplify my vector data to display it more efficiently [closed]

I have >1Billions points data (in geoparquet but could gpck) that I have to display in QGIS in a scale that doesn't need such precision (=we will not see all the details). It takes age to load in ...
darrepac's user avatar
0 votes
1 answer
82 views

QGIS Simplifying polygons with keeping points inside of them

I'm creating a processing where I do calculations on address points inside of counties. I need to generalise county polygons in order to make my processing faster. How do I make sure that address ...
Adam Korejwo's user avatar
2 votes
0 answers
78 views

Seeking algorithm for polygon straightening

I have a polygon that looks like this: I want to get a result that ideally looks like this: The best that I can come up with is a polygon simplification using shapely in Python: Which algorithm ...
Марина Лисниченко's user avatar
3 votes
3 answers
317 views

Why simplify algorithm has no effect on input in QGIS?

I have a LineString layer that I need to reduce the number of vertices. For example, some straight lines have intermediate vertices that add no value and should be removed. A slight loss of accuracy, ...
I have no idea what I'm doing's user avatar
1 vote
1 answer
415 views

What are strategies to simplify a vectorized raster layer?

For a GIS web viewer I am building, I plan to use large sets of vector data on coral reefs (source: Allen Coral Atlas). When viewing the downloaded data, it seems that the original source was raster ...
Sytze's user avatar
  • 731
1 vote
0 answers
110 views

Speed up intersection on large polygons with PyQGIS?

Is there a way to speed up my script? I am new to PyQGIS. I am using QGIS 3.16. What I need: I have 50 polygons (up to 1.675.000 hectares, mean 420.000 ha; one shapefile per polygon) and for each of ...
Pompoensoep's user avatar
1 vote
0 answers
39 views

Invisible layers when splitting vectors after simplifying in QGIS

I am working with elevation curves and I want to group curves by elevation. I can do it with the Split Vector Layer tool (Vector, Data management Tools) and choose ELEV as a unique ID field. However, ...
Giacca Zm's user avatar
4 votes
3 answers
554 views

Simplify multipolygon removing small gaps in PostGIS

Is there a way to simplify multipolygon by removing small gaps in PostGIS? Example: Original: Simplified: It could also simplify the shape as ST_Simplify does but in addition it should remove small ...
Martin Ždila's user avatar
0 votes
1 answer
330 views

Can't call PostGIS ST_Simplify

How can I call PostGIS's ST_Simplify function? postgres=# SELECT ST_Simplify( geom, 0.1 ) FROM mains; ERROR: function st_simplify(geography, numeric) does not exist LINE 1: SELECT ST_Simplify( geom, ...
Lee Goddard's user avatar
1 vote
1 answer
57 views

Simplifying Water Areas in QGIS for Artwork

I am using QGIS to create geographic artwork with topo and water features. I have downloaded the NHDWaterbody dataset from the USGS. Some of the wetlands are causing me real issues. For example, here ...
Justin's user avatar
  • 111
1 vote
1 answer
2k views

Warnings() in functions sf package

I'm running the code below and I get several "warnings". I used the sf_use_s2(FALSE) function to work with plane coordinates following the old way of the 'sf' package but even so I keep ...
Caroline Portal's user avatar
0 votes
0 answers
101 views

Ovals are being automatically simplified when drawn using ArcGIS Pro

Sometimes when I am drawing ellipses in a polygon shapefile, they save correctly and then simplify themselves into angular shapes. I don't understand why this is happening or only happens sometimes, ...
meag's user avatar
  • 1
0 votes
1 answer
98 views

Simplifying polygon product of erase tool results due to small gaps in erase features

I am using ArcGIS Pro 2.9 erase tools to erase overlaying polygons as such: with blue circles as input features and gray polygons as erase features. And here are my result: there are awkward lines ...
greensquare68's user avatar
2 votes
0 answers
168 views

Geometry simplification for large scale aggregations in GEE

When aggregating on a large scale in GEE, does geometry simplification matter? For example, when aggregating climate data on 30 km/pixel (e.g. NEX-GDDP), does it make computational sense to change ...
Basile's user avatar
  • 3,543
1 vote
0 answers
168 views

QGIS Simplify tool resulting in missing features [closed]

I am a very new QGIS user, but have learned much from searching this site for tools that are appropriate for what I am doing. However, I have reached a roadblock that has stumped me the past several ...
Douglas Frank's user avatar
0 votes
1 answer
166 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, ...
SLO_planner's user avatar
1 vote
1 answer
188 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 ...
gizmogaurav's user avatar
0 votes
0 answers
49 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 ...
Angeles221's user avatar
0 votes
0 answers
23 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 ...
gizmogaurav's user avatar
3 votes
2 answers
653 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 ...
gizmogaurav's user avatar
2 votes
1 answer
181 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 ...
pyGisServer's user avatar
9 votes
5 answers
1k views

Simplifying polygon by inner angle in QGIS

I'm trying to simplify a polygon using the interior angle of a vertex as the "tolerance" instead of the distance between vertexes. For e.g. the polygon in the image below would lose one ...
Alec McKay's user avatar
2 votes
1 answer
439 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 ...
Foaly's user avatar
  • 323
2 votes
1 answer
353 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 ...
IberOikos's user avatar
3 votes
1 answer
816 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 ...
Tomáš Černý's user avatar
3 votes
1 answer
153 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" ...
user724910's user avatar
1 vote
1 answer
669 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 ...
user3462098's user avatar
3 votes
1 answer
882 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 ...
Philip B's user avatar
2 votes
0 answers
529 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 ...
naught101's user avatar
  • 496
0 votes
1 answer
88 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 ...
davehughes87's user avatar
0 votes
0 answers
56 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. ...
hawkman's user avatar
4 votes
3 answers
633 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 ...
Jivan's user avatar
  • 283
1 vote
1 answer
648 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 ...
SeaGo's user avatar
  • 11
8 votes
1 answer
1k 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 ...
RyanKDalton's user avatar
  • 23.1k
2 votes
1 answer
489 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 ...
GStav's user avatar
  • 309
0 votes
1 answer
348 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 ...
Peter Krauss's user avatar
  • 2,292
2 votes
0 answers
163 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. ...
ann chi's user avatar
  • 69
3 votes
3 answers
244 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 ...
Matthew Law's user avatar
3 votes
2 answers
392 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, ...
Llaves's user avatar
  • 5,963
5 votes
3 answers
1k 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 ...
Jan Málek's user avatar
4 votes
2 answers
848 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 ...
Veronica's user avatar
1 vote
2 answers
1k 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] ,[...
Giox's user avatar
  • 253
2 votes
1 answer
61 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/...
John_Beatty's user avatar
2 votes
0 answers
197 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 ...
fhristov's user avatar
8 votes
1 answer
7k 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 ...
RutgerH's user avatar
  • 3,285
3 votes
0 answers
430 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?
Karthik's user avatar
  • 249
1 vote
1 answer
601 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 ...
julien's user avatar
  • 10.2k