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.
177 questions
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Simplify geometries but keep them contiguous [duplicate]
I have several detailed contiguous areas. I need to turn each one into KML, but when I do so, the end result is too large (in terms of memory). Using PostGIS I need to simplify these geometries but ...
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How to find fluctuant parts in a trajectory
I am currently doing an assignment on how to compress a trajectory. Given a trajectory T1 in figure 1, and I want to get a compressed version as T2. For segments p0~p3 and p6~p9 in T2, I can obtain ...
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Can I simplify geometry on the fly in a ArcGIS JavaScript map viewer?
We've got a polygon feature class of parcels around a lake boundary that is incredibly accurate. The editor did a really thorough job of following all the inlets and meanders along the edge. From just ...
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Simplify shapefiles [closed]
I've shapefiles with me and I want to de-code those file and want to build a custom map. Could someone let me know how can I do that with out using Python code.
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Simplify/generalize Polygons and keep topology of different layers PostGIS/QGIS
I have some polygons of a country, states, districts, communities and I want to simplify the geometry.
I already simplified the geometry of each layer but afterwards of course it doesnt fit with the ...
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Resolve Building Conflicts - the open source way?
In ArcGIS there is a tool called Resolve Building Conflicts and I'd like to achieve the same using only open source tools (QGIS, GDAL etc), preferably on Mac OS instead.
In the long run I'm trying to ...
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C/C++ function to return minimum set of points required to represent a geometric shape
I am looking for a method from Grass, GEOS, or similar that will delete those points in a geometry which do not affect its shape.
Example 1
+----+----+
p0 p1 p2
p1 can be deleted without ...
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Generalizing exact location of certain data points using Carto CSS?
I am dealing with some sensitive data for which providing a high resolution of accuracy of the location would be detrimental. However, the general location is not sensitive and useful to share.
I ...
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PostGIS: How to dissolve vector data
I have a few scenarios where I need to dissolve vector data, and I'm wondering how to do this using PostGIS. What would the queries look like to perform these operations?
Below I'll describe the ...
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2
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QGIS simplify geometries shifts polygons north
I'm trying to simplify polygons in a shapefile using the "Simplify Geometries" tool in QGIS 2.10 (Pisa). This works as expected, except for one strange effect: the resulting features (shown in green) ...
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Combine files in TopoJSON when one is simplified differently to the other
I have two .shp files, I am separately converting these to GeoJSON with ogr2ogr.exe and then combining the files with TopoJSON.
Each file independently becomes a ~200kb topojson file, however the ...
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Simplifying Ways in OpenStreetMap Data
Is there a (current) best practice to simplify ways? I have found:
https://github.com/podolsir/osmosis-simplifyways
But besides not being alive, here (http://permalink.gmane.org/gmane.comp.gis....
user54586
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3
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How to anonymise a gps file?
Imagine you have a GPS trace that you want to make anonymous, in the legal sense. How would you do this? Is snapping to the nearest x distance and stripping out the time enough? Are there ...
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Cannot Select 'Input line or polygon vector layer' when trying to simplify Shapefile
I'm trying to simplify a Shapefile by opening it in QGIS, Go to the Vector menu, selecting Geometry tools, and selecting Simplify Geometries...
When I do this I get a modal window that I can fill out ...
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Is there a difference in results between Simplifying a geometry by different projections?
We have geometries in a PostGIS database projected in srid 4326. We need to have these geometries simplified with ST_SimplifyPreserveTopology.
My question is whether this geometry needs to be ...
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Removing unnecessary vertices?
I have over sampled polygons that I need to simplify, without changing the shape. basically, I want to reduce the number of vertices, by eliminating the ones that are useless and have the polygons ...
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Query to merge simplified polygons according to the map scale-factor [closed]
I'm trying to construct a view in PostgreSQL that simplify polygons according to the map scale-factor. Basically I was reading this thread http://linfiniti.com/2011/06/scale-dependent-generalization-...
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QGIS - Simplification process creates a new polygon - how to avoid it?
I am trying to simplify a layer made of polygons.
I have used different methods but the new simplified layer has a polygon which intersect with itself, thus creating a "new" polygon.
Please see ...
user52354
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ArcGIS Raster To Multipoint Mac/OSX alternative
Is there an alternative to the ArcGIS Raster To Multipoint tool for Macs? The VIP thinning method is particularly of use. A comparative point cloud thinning/simplification tool to this would just as ...
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writeOGR with a spatialpolygon simplified by gSimplify
I'm using gSimplify (rgeos package) to simplify the geometries of a shapefile. The funcion works good, but now I can't write the output in a new shapefile.
I tried some ways:
writeOGR(simplyshape, ...
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How to fill a hole - with islands within?
In QGIS I have simplified a layer.
At the end of the simplification process (using GRASS v.generalize), my final layer "lost" a polygon: see white space in image:
How can I recreate a polygon which ...
user52354
2
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1
answer
785
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simplify tiled geometries while preserving anything on the edge
I have a dataset of polygons split into evenly sized tiles. How can I go about simplifying them, but not along the tile edges, so that there aren't any gaps between continuous features when the tiles ...
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Getting simplified UK boundary data?
I have some recent data that is at the Lower Super Output Area (LSOA) level for Greater Manchester. I wrongly assumed that the data was for the latest LSOA boundaries, i.e. for the 2011 boundaries.
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What is "Simplify tolerance" in QGIS's Simplify geometries tool?
I am trying to use QGIS 2.8 to simplify vector geometries. But I do not understand the significance of the Simplify tolerance value in the Simplify geometries tool.
The documentation does not ...
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Complex Shapefile Compression Advice
I'm looking for some advice on how I can simplify this very detailed shapefile to ultimately be used for the web (as topojson) as a interactive heatmap. It was originally created from a raster file (...
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How Does Ogr2Ogr Simplify Work?
Can someone explain how the ogr2ogr simplify works?
I am trying to use raster data which has a spectral resolution of 30m. The vector file that I am trying to import into Google Fusion is large in ...
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Collapsing multiple lines into single line?
I need to create a route (line) feature class from another feature class that contains multiple lines making up the same route.
pic 1 shows the original feature class with the multiple lines.
pic 2 ...
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1
answer
710
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Reducing number of points, keeping most recent data within given distance, using QGIS?
I have a HUGE dataset of points that were collected along a route. The data may change daily, and the most recent data is the most important. What I would like to do is take only 1 point from a given ...
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Simplifying polygons in ArcGIS considering contains-one-point topology rule?
I want to simplify polygons using the "Simplify Polygon (Cartography)" tool in ArcGIS 10.2. Additionaly there is one point in each polygon and this condition should still be fulfilled after ...
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Simplify a polygon dataset with a minimum distance between the new vertices
I would like to simplify a polygon shapefile where the resulting output has a minimum distance of 5 kilometres between the new vertices.
We have ArcMap 10 on an ArcView license, FME and QGIS.
I have ...
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Simplify a road network to obtain the intersections
In QGIS 2.6.1 in Ubuntu, I want to measure the density of block in this city (FYI my final aim is to measure the TOD level). I have the road network from French national IGN dataset BDTopo.
I have ...
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How to simplify polygon shapefile and maintain topology? [duplicate]
I'm looking for a straightforward answer that actually works...not a 'duplicate question' flag. None of the other solutions posted in similar threads actually work...they all have dead-end answers and/...
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Why are my polygons automatically simplified/generalised when merging them in ArcMap 10.2?
I am creating a small land use map, as an exercise for visual image interpretation. I created a shapefile and started digitising polyogons with the polygon tool. The problem is that some of my ...
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1
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Shapely's simplify won't simplify any more
I have a multipolygon in shapely, and I want to simplify it until it has less than a certain number of points. When I use the preseve_topology=False argument to geom.simplify, I can get the number of ...
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Generalize lines with specific points
It's been a while since I was here. I have this problem now.
I have electricity line feature class and point feature class intersecting line features. What I need to do is simplify this line feature ...
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How can I find a Douglas-Peucker algorithm for simplification? [duplicate]
I want to understand simplification methods in GIS. I searched the Internet and found that the best simplification method is the Douglas-Peucker algorithm. I could not find any information about the ...
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Keep synchronization when simplify features from different data source
We have two shapefile data sources:
1 water-riverbank.shp
With geometry type of Polygon which stands for the area of water
2water-riverline.shp.
With geometry type of LineString which stands for ...
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ogr SimplifyPreserveTopology does not keep the Topology
I use ogr2ogr to simplify a layer of polyline, from the document:
-simplify tolerance: (starting with GDAL 1.9.0) distance tolerance for simplification. This method will preserve topology, in ...
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Simplify polyline with the intersection point kept
I have a some line and polygon features which consist of too many points, so I tried to simplify them.
I found the "Ramer–Douglas–Peucker algorithm".
I think it will work well for a single feature (...
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1
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Competing approaches to line & polygon simplification
There seems to be a few theoretical options around at the moment for geometric simplification. Douglas–Peucker seems the most established, followed by Visvalingam's approach (used by d3.js). Now ...
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How to simplify streets such that separate driving tracks are reduced?
Streets in Openstreetmap have more detail than I need. For instance, I do not need separate street tracks for each driving direction; instead I just want to show the general path of the street. ...
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How do I smooth edges of polygons in QGIS? [duplicate]
Is there a built in function or plugin I can use to achieve smooth lines for my polygons instead of the blocky ones I have now?
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Reducing point numbers in a certain area
We have a list of poi data in our database(Access mdb db), and we have a web service which serve data by a specified BoundingBox.
However we found that the returned points are too close to another at ...
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How to disable "Simplify geometry" via Python?
After I've loaded a layer from a table in my db I'd like to disable the 'Simplify geometry' (found in Layers/Properties/Rendering) programatically using Python.
I've tried several versions of ...
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Simplify the straight sections of (multi)Linestring in PostgreSQL/PostGIS leaving the curved sections untouched
I have (multi)linestrings containing upwards of 5000 points and I want to perform two simplifications possibly using Ramer Douglas Peucker or alternative methods in PostGIS. The (multi)linestrings ...
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Algorithm to move polygon nodes when simplifying
I want to simplify polygons that come from a raster analysis. In order to avoid overlap and gaps, I first convert my polygons to lines. The problem is that all algorithm are then keeping the two end ...
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Simplifying polygon by number of points in QGIS
I am aware you are able to simplify polygons in QGIS based on distance tolerance but my questions is, is there a way to simplify based on a set maximum number of desired points?
For example, if the ...
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How to maintain right-angles when buffering?
When buffering some polygons I am trying to avoid the curved buffered area like this:
I'm trying to do thins within an FME workbench but if someone knows how its done in other software that would ...
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Simplify table of linestrings
I have a PostGIS table of linestrings representing a road network. I want to simplify the geometries such that only lines that connect road junctions are stored.
At the moment the table has a large ...
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3
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Seeking algorithm for Lossless Polygon Simplification
Is there a standard/recommended algorithm for simplifying a polygon without shrinking any of its original boundaries?
Right now I'm using TopologyPreservingSimplifer within JTS and running into ...
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