Questions tagged [generalization]

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How to simplify and generalise global data for cartography?

I have a TIFF that shows biodiversity and I want to create a nicely looking cartography output. The data look like this If you can observe there are a lot of 'dots' and things can get a bit messy ...
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0answers
24 views

Clean up self-intersecting polylines in QGIS?

I have GPS data that contains self-intersections. This happens when someone walks around on "the same spot". Is there a way to clean up these in QGIS? I tried Smooth but that did not do the trick.
3
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3answers
46 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 ...
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0answers
86 views

Generalizing railways from OpenStreetMap using ArcGIS Desktop?

I have dataset of railways from OpenStreetMap. It is really detailed. But i want to make generalization for map scale 1:500 000: remove small details of the railways and short branches. I`ve used ...
2
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0answers
60 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 ...
3
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2answers
198 views

Automatically fill gaps and merge freshly generated polygons with the longest adjacent polygon

I get polylines automatically generated from AutoCAD from a colleague. Converting them into polygons with QGIS 3.6, I find out some sliver polygons and gaps in between, as shown in the picture below : ...
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0answers
24 views

Reclass raster map areas smaller than specified area size

I need to reclassify raster areas smaller than 100m2 (0.01 ha) to new ones. r.reclass. area from GRASS GIS does the job for some raster sizes, but simply stucks/doesn't work on bigger ones (54000 x ...
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0answers
65 views

Simplify a polyline/polygon using a threshold on maximum number of vertices in PostGIS?

The various simplification functions in PostGIS (e.g. ST_Simplify) uses a tolerance parameter for the maximum allowable deviation of the generalized shape from the original. My question is: Is there ...
2
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0answers
71 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?
1
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1answer
81 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
64 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
48 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, ...
1
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0answers
39 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, ...
0
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1answer
74 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
77 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
146 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
48 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
209 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
88 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 ...
1
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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
52 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 ...
1
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0answers
543 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: ...
1
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1answer
143 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. ...
1
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0answers
83 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
199 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
52 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
554 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
269 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
vote
1answer
84 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
197 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
223 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 ...
1
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0answers
136 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
263 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 ...
2
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1answer
488 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
222 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
59 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 ...
3
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1answer
159 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.
3
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0answers
159 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 ...
1
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0answers
52 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 ...
1
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0answers
29 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 ...
1
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0answers
205 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
132 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
907 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
votes
1answer
540 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
1k 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
votes
1answer
90 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
732 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
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1answer
567 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 ...