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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11
votes
5answers
3k views

Simplifying polygons to linestring

I would like to simplify some polygons that represent rivers into linestrings. I assume that holes in polygons can be omitted. Anybody has some good idea how to simply do it? It would be nice, if it ...
1
vote
0answers
21 views

Filtering Small Areas of Shapefiles Using R

I'm trying to use the method proposed by the @ialm in the Question "How to speed up the plotting of polygons in R?" There, he loads the maps using getData from the raster package, I tested and it ...
0
votes
0answers
19 views

How to calculate tolerance for TopologyPreservingSimplifier in JTS?

I am trying to simplify some areal geometries (POLYGON\MULTIPOLYGON) using JTS's TopologyPreservingSimplifier.simplify(Geometry geom, double distanceTolerance) From the JavaDoc: void ...
1
vote
2answers
1k views

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 ...
2
votes
1answer
39 views

Generalizing (simplifying) polygon shapefile or feature class in ArcMap while preserving topology?

I came across How to generalize a polygon file and maintain topology in QGIS? which asks for a QGIS solution to my exact question. I'm trying to do this in ArcMap. I start with a polygon shapefile ...
2
votes
1answer
59 views

Using Chaiken Method parameters for smoothing polygon vectors in QGIS [duplicate]

I've been trying to smooth a huge polygon, that is result of a segmentation export. I'd like to know what's the best parameters to use Chaiken Method to get smooth curved boundaries on QGIS 2.14. I ...
25
votes
10answers
4k views

Existing solutions to automate generalisation/simplification of geographical data?

I am looking for existing solutions (softwares, libraries, methods, etc.) to automate the generalisation/simplification of geographical data as presented there, and also there. Do you know and use ...
1
vote
0answers
18 views

How can I use ST_Contains/ST_Overlaps with non-simple lines?

Following the SQL of the accepted answer to How to get smallest line segments from intersection + difference of multiple overlapping lines? copied below. I'm having some difficulties assign the ids of ...
1
vote
0answers
31 views

ogr2ogr (or other) simplification of polygons with shared boundaries

I am trying to simplify a collection of 100,000 or so polygons containing nearly 4 million vertices. The data is stored in a 2GB shapefile so there is no explicit representation of the topology ...
5
votes
1answer
430 views

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 ...
1
vote
2answers
68 views

Simplify geometries but keep them contiguous

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 ...
4
votes
2answers
33 views

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 ...
1
vote
1answer
26 views

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 ...
0
votes
0answers
24 views

Can GeoServer be asked to clip a WFS response?

I'm fairly new to GIS, so I'm not very familiar with all the terminology and standards. What I need is a webservice that returns geographical polygons (countries and administrative regions) as ...
3
votes
1answer
218 views

QGIS 2.6 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 ...
-3
votes
1answer
58 views

Simplify shape files [closed]

I've shape files 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.
3
votes
2answers
139 views

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 ...
4
votes
1answer
1k views

Changing the scale (generalisation) in ArcGIS 10

I have 2 polygon layers, accordingly 1:10 000 and 1:500 000. I want to generalize the first layer from 1:10 000 to 1:500 000. I tried using Simplify polygon tool, and since these scales relate to ...
1
vote
0answers
53 views

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 ...
2
votes
0answers
36 views

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 ...
2
votes
1answer
59 views

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 ...
1
vote
1answer
104 views

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 ...
2
votes
1answer
32 views

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) ...
5
votes
0answers
220 views

How do I simplify the straight sections of (multi)Linestring in PostGres/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 ...
2
votes
0answers
42 views

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 ...
11
votes
2answers
175 views

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 ...
0
votes
2answers
91 views

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 ...
1
vote
2answers
50 views

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 ...
5
votes
1answer
68 views

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 ...
1
vote
0answers
84 views

Query to merge simplified polygons according to the map scale-factor

I'm trying to construct a view in PostgreSQL that simplify polygons according to the map scale-factor. Basically I was reading this thread ...
1
vote
0answers
46 views

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 ...
0
votes
1answer
73 views

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 ...
4
votes
2answers
299 views

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, ...
5
votes
1answer
536 views

Simplifying polygons made from binary rasters using ArcGIS Spatial Analyst?

I'm using MaxEnt to produce a species presence / absence raster layer. It works fine but I have to choose a cut off point for what constitutes presence or absence. As a result I end up with a lot of ...
2
votes
1answer
196 views

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 ...
1
vote
1answer
77 views

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 ...
0
votes
1answer
129 views

What is the best way to get 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. ...
2
votes
2answers
282 views

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 ...
0
votes
0answers
29 views

Draw (adjacent) GIS-shapes, reduced and “rounded”

as the title says: I want to draw (C#, WinForms application) adjacent polygons stored in an GIS-database (SQL Server 2012, geography-datatype). The data source is OpenStreetMap administrative ...
6
votes
2answers
137 views

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 ...
1
vote
1answer
593 views

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 ...
3
votes
1answer
333 views

Collapse multiple lines into a 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 ...
1
vote
1answer
121 views

Reduce number of points, keeping most recent data within a given distance

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 ...
0
votes
1answer
113 views

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 ...
3
votes
4answers
573 views

Redistribute linestring vertices to specified distance

I use a groundwater model program called GMS, and it has a very useful function "Redistribute vertices" (more info). I use this function all the time to both simplify and provide regular spacings ...
3
votes
2answers
2k views

Simplifying Shapefile using ArcGIS Desktop or alternative?

I have a shapefile that contains neighborhood boundaries that I want to simplify. Right now I am thinking of converting the shapefile to Google maps KML so I can insert the boundaries into the map as ...
2
votes
1answer
211 views

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 ...
18
votes
5answers
2k views

How to simplify a routable network?

I have a network graph that I need to simplify in the sense of reducing the number of edges. The idea would be to merge nodes that are located close together and remove the connecting short edges. ...
1
vote
2answers
130 views

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 ...
3
votes
0answers
80 views

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 ...