Skip to main content
Geographic Information Systems

Questions tagged [simplify]

Ask Question

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.

181 questions
Newest Active Bountied Unanswered
Filter by
Sorted by
Tagged with
0 votes
3 answers
88 views

I am doing a viewshed analysis on a DEM .tiff file. I would like to convert the viewshed raster into vector geometry in the format of .geojson, which i have achieved, although, the result is not good. ...
Ólavur Nón's user avatar
  • 113
-1 votes
1 answer
67 views

How do I simplify complex polygons in order to get simpler detailed polygons like this : ... keeping their topology
user299405's user avatar
  • 1
0 votes
0 answers
35 views

I'm working with a map of the world from GADM dataset stored as JSON. The precision of the map is way too small for serving a web application so I would like to simplify it to 0.01° and thus reduce ...
Pierrick Rambaud's user avatar
  • 3,460
1 vote
0 answers
87 views

I am trying in QGIS to simplify the geometries of the world's country borders (from here for example) to achieve a clean, generalized map display. To do this, I am using the v.generalize tool provided ...
B Legrand's user avatar
  • 141
-2 votes
1 answer
216 views

I am looking for a way of simplifying my GeoJSON file by removing overlapping lineparts between adjacent polygons. I have a GeoJSON file with polygons of cadastral parcels which, by definition, are ...
Sebastiaan's user avatar
  • 7
0 votes
1 answer
369 views

I want to simplify adjacent polygons (GADM zones level 1) with Python while maintaining shared borders. The general problem is well explained at Simplifying Polygonal Coverages with JTS. The best ...
JoMe's user avatar
  • 17
0 votes
1 answer
345 views

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....
PixelExplorer's user avatar
  • 53
0 votes
0 answers
40 views

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
  • 1
0 votes
1 answer
183 views

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
  • 43
0 votes
1 answer
127 views

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
  • 11
2 votes
0 answers
123 views

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
  • 665
3 votes
3 answers
706 views

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
  • 133
1 vote
1 answer
862 views

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
  • 800
1 vote
0 answers
159 views

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
  • 59
1 vote
0 answers
50 views

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
  • 11
4 votes
3 answers
801 views

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
  • 572
0 votes
1 answer
528 views

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
  • 522
1 vote
1 answer
83 views

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
2 votes
1 answer
3k views

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
  • 33
0 votes
0 answers
152 views

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
117 views

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
  • 89
2 votes
0 answers
180 views

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
  • 3,603
1 vote
0 answers
219 views

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
  • 19
0 votes
1 answer
247 views

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
  • 9
1 vote
1 answer
246 views

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
  • 113
0 votes
0 answers
64 views

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
  • 1
0 votes
0 answers
24 views

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
  • 113
4 votes
2 answers
913 views

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
  • 113
2 votes
1 answer
283 views

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
  • 69
9 votes
5 answers
1k views

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
  • 93
2 votes
1 answer
526 views

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
434 views

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
  • 87
3 votes
1 answer
1k views

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
  • 81
3 votes
1 answer
223 views

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
  • 33
1 vote
1 answer
1k views

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
  • 33
3 votes
1 answer
1k views

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
  • 61
2 votes
0 answers
633 views

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
  • 494
0 votes
1 answer
127 views

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
  • 691
0 votes
0 answers
70 views

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
  • 1
4 votes
3 answers
780 views

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
733 views

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

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
  • 23.3k
2 votes
1 answer
569 views

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
  • 349
0 votes
1 answer
425 views

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
  • 2,572
2 votes
0 answers
180 views

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
480 views

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
  • 273
3 votes
2 answers
477 views

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
  • 6,063
5 votes
3 answers
1k views

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
  • 157
4 votes
2 answers
1k views

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
  • 41
1 vote
2 answers
1k views

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
  • 273

1
2 3 4