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Questions tagged [generalization]

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0answers
32 views

How to generalize or simplify the multipolygon in PostGIS without missing any 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?
1
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1answer
45 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 ...
2
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0answers
23 views

Conditional Expanding in ArcGIS Desktop?

I would like to reclassify a LC map given some conditional rules (raster with 8 classes total). Using the illustration, I would like to expand the green pixels (two distinct classes) on the white ...
1
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1answer
19 views

v.generalize in QGIS throwing “Unable to create table” error

I am trying to smoothen few polyline shapefiles using v.generalize in QGIS 3.4. But it's not working. Even i tried the same in QGIS 2.18. Getting the same error. Tried the same process in GRASS 7.4.2....
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0answers
39 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, ...
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0answers
29 views

How to remove complicated shapes in ArcGIS - generalization [duplicate]

What can be the way of simplifying polygons in ArcMap? I have a shapefile with buildings and I have to make them as simple as it's possible. I used already some tools, like: dissolve, union, ...
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1answer
48 views

Avoiding thin parts of polygons using ArcGIS Desktop?

I've used Simplify Polygon with 'Maximum Allowable Offset' 250m, and then Aggregate Polygons with 'Aggregation Distance' also 250m (opposite order also tested). Still I have thin parts of polygons as ...
5
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1answer
55 views

Getting WHERE statement to work in v.generalize?

I have a shape (its topology is terrible but I don't think it's the problem). I'm trying to simplify it to reduced it's size using v.generalise. I succeeded at reducing the whole shape but I ...
2
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1answer
82 views

Display multiple lines as one line in QGIS

I am working with the OSM Dataset and can´t find a way to display rails in a proper way. In a big scale the rails are displaying fine but as soon the lines begin to overlap in a smaller scale I don´t ...
3
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1answer
41 views

Is there a built in way to reduce the amount of points in an IElement

I have a polyline element and I want to reduce the number of points (vertices?) that make up the line. I know it will make the curved sections jagged and that is fine. I just want to control (perhaps ...
2
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2answers
181 views

Cartographic generalization: Dissolve “neighbour” / bordering polygon objects in QGIS

I have a polygon layer with buildings for the area of the whole city. My question is how to dissolve/aggregate/merge only those buildings, that are "neighbours", in a sense that they share at least ...
1
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0answers
62 views

How to generalize shape with PyQGIS without much Distortion in the shape?

I was trying to generalize the the inner boundaries of the polygon. Looking for a PyQGIS solution for that any other possible python solution will be fine. I tried convex hull and simplify geometry ...
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0answers
25 views

Smooth Data Values Across Geographies with Zero Population

Looking to fill in gaps through generalizing a population count across U.S. counties. I.e., if a county has 0 population, but is surrounded by 5 non-zero counties, then change the 0-population county ...
1
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1answer
46 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 ...
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0answers
350 views

Generalize Polygons in QGIS 3.0

I would like to use different generalization tools for polygons in QGIS 3.0. Especially for aggregation, simplifying and smoothing. Back using QGIS 2.8 there were the following possibilities: ...
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1answer
136 views

How to generalize QGIS 3.0 Model so that I can install on multiple computers without setting up on every computer?

I am trying to create a model to work on multiple computers with little editing. I am working in QGIS 3.0. I am trying to get the model to first set the style for the layers based on a predefined qlr. ...
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0answers
74 views

Speeding up workflow of generalizing OpenStreetMap road data?

Whenever I want to use OSM data for medium scale maps (e.g. 1:200.000) I run into problems. On the screenshot below one can see the orange street that goes from north to south. It has the attribut ...
2
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0answers
142 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 ...
0
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1answer
45 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 ...
1
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1answer
342 views

Merging unconnected line segments using ArcGIS Desktop?

I am looking for a way to connect line segments that are unconnected. It is a shapefile for a network of rivers and all the lines are slightly disconnected. Is there something like aggregate ...
1
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0answers
203 views

How to reduce the density of points based on zoom level

I have a Polyline like the one shown in the example, representing the path of a vehicle. GeoJSON markers show the vehicle's position over time. How can I reduce the density of the markers when the ...
1
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1answer
64 views

Options for generalizing raster?

I have a DTM raster which has too high a spatial resolution for my intended use, and I need it more generalized. Can't put my finger on how much more, but considerably more. My first thought was to ...
1
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1answer
146 views

Generalising Rasters using .ovr pyramid data?

I have to produce some lower spatial resolution rasters from a large number of very big geotiffs (c.800GB). It occured to me that since I've produced the pyramid overviews using GDAL already I could ...
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2answers
140 views

What is the process by which ONS creates “Generalised” and “Ultra Generalised” Clipped Boundary shapefiles?

The ONS (Office for National Statistics) in the UK makes available a large number of shapefiles based on geocoded statistical data sets and admin/demographic boundary shapefiles. These are deposited ...
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0answers
125 views

Line generalization not working

After having installed the plugin - Cartographic Line Generalization - I try to open the tool in the Plugins menu and receive the following error: AttributeError: 'NoneType' object has no attribute '...
1
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1answer
238 views

How to generalize polygones in QGIS

I am working with vectorized greyscale images converted into polygon layers by the QGIS vetorize tool. Currently I am using a rather long way to get rid of small polygones. I convert the polygons ...
3
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1answer
389 views

Raster smoothing/generalisation in FME

I'm trying to find an equivalent in FME to the Majority Filter in ArcGIS (http://desktop.arcgis.com/en/arcmap/10.3/tools/spatial-analyst-toolbox/majority-filter.htm), I've had no success this far... ...
3
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1answer
180 views

Jagged Polygon Edge Generalization in ArcGIS Desktop?

I have a polygon which the edge is quite normal when zoomed out: But when zoomed in this is how the edge looks like (jagged) because it was converted pixel by pixel from a raster, is there a ...
3
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0answers
58 views

What amount should be kept on map? [closed]

I am generalizing geological map, for initial process I am dealing with small polygons which are less than minimum separability unit and try either remove them or enlarge. For the first step I am ...
4
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1answer
152 views

qgis: generalisation & covex - how to? what plugin?

I'm looking for a way to generalize and simlify polygon to remove "internal spikes" as ilustrated below. The violet in input and green expected poligon.
4
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0answers
146 views

How to accelerate v.generalize on massive vector data?

I have a big problem with my vector dataset (more than 1 million entities) and v.generalize in grass 7.0.5 and 6.4 (64 bits for both). I try to use Douglas method on this dataset but it is very very ...
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0answers
48 views

Simplify geometry of multiple features without losing shape [duplicate]

I am simplifying administrative boundaries using a high simplify tolerance (which is my intention so as to get a minimalist appearance). However, after simplification, the borders of the regions no ...
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0answers
28 views

Square polygons that are covered by trees

I would like to know if there is a way to square polygons? I would like to calculate the total square meters of houses. I have extracted the buildings as well as tree coverage but I am unable to get ...
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0answers
180 views

How to smooth “internal” polygon borders [closed]

This is my first foray into GIS and GIS software. I am using ArcMap currently. I have a shapefile of the world divided into different ecological regions. I would like to reduce the file size by ...
1
vote
1answer
116 views

Generalizing road polylines?

I have a dataset of road lines obtained from digitized aerial imagery and I want to automate the generalization procedures using arcGIS model builder. I am using the ArcGIS 10.3 desktop suite. I have ...
4
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2answers
641 views

Removing unnecessary vertices at places with no change of direction?

I am aware that this question has been asked here: Removing unnecessary vertices?. I want to focus a different point. How to remove unnecessary vertices without changing the shape at all. As you can ...
2
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1answer
411 views

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

I came across Generalizing polygon file while maintaining 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 (...
1
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1answer
896 views

How to do a Loop with a condition in Model Builder?

Can I loop a set of actions in model builder while a specific features rows are 1 or more. Some background: I have a point layer where I've created a workflow that: first selects the row with the ...
3
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1answer
86 views

Loop and perform loop in order depending on attribute

I have a lot of points in one layer. All of which represent the same type of real world feature. I want to perform a delete identical within XY of each point but in a specific order. (by splitting ...
8
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3answers
659 views

Why are the holes in my polygons not generalized?

I have one polygon layer with many holes. I would like to generalize it. I used v.generalize of grass. With it, I used chaiken algorithm. But, only the borders of polygons were generalized, the holes ...
1
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1answer
94 views

How is width commonly defined for areal features?

Map generalization guidelines, for instance applicable to CORINE Land Cover or Polish BDOO databases state inclusion criteria for areal features like "area should be > 250 000 m^2 and width should be >...
6
votes
1answer
495 views

How to cartographically generalise buildings/settlements in QGIS?

I have a set of buildings in a polygon layer which I'm going to use in a 50k map. Since the buildings are tiny I cannot show the actual form of the building, instead I'm taking the centroid of the ...
1
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0answers
122 views

How to generalize a raster with noisy edges with ArcGIS Desktop?

I'm trying to generalize a raster to get clean edges (see sample and "optimal" result below). However the borders bleed into each other to a rather high degree. I hacked away at the raster using ...
2
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0answers
68 views

Avoiding edges using GRASS generalization?

I'm trying to process the national wide land cover data into vector polygons. In order to be quick I separate the data into several tiles and process them in parallel. process flow is : 1. v.in.ogr ...
4
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2answers
2k 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 ...
1
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1answer
95 views

Problem with low quality tiff

I have the problem with low quality raster. Now it looks like this: a busy cat http://iv.pl/images/53039057684486451032.png I would like to change this to looks like this: a busy cat http://iv.pl/...
3
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1answer
111 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 ...
3
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1answer
579 views

How to produce outline of a coastline?

I have polygon dataset containing quite a complicated coastline. How can I produce an outline of that coastline? Please see the image: my dataset is in green and the coastline I need to get is in ...
2
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1answer
101 views

Creating fishnet from thematic polygon data?

I need to create a regular grid containing attributes from other thematic data from ecological data. I am in effect creating a homogenous polygon raster and adding information from another dataset ...
1
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0answers
125 views

Combine two parallel lines to one with postgis [duplicate]

In OpenStreetMap, a highway=motorway consists out of two parallel lines, each representing one direction: On a professional map the two lanes get combined to one single line and drawn with a middle ...