Questions tagged [density]

A density map depicts a number of objects per unit area.

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12 views

Making informative legend for Kernel Density Estimate in QGIS?

I have used heatmap (kernel density estimation) in QGIS 3.0.1 to make a heatmap of boat counts. In my point data-each point is one boat. Then, in my kernel, I have used a 500m radius, with 500m pixel ...
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51 views

Producing density map using QGIS?

I have placed a grid onto an open source Ordnance Survey map that corresponds to Ordnance Survey eastings and northings. I have a value for each grid square between zero and 30. How do I use these ...
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1answer
60 views

QGIS 3 building density calculations

I have layer of buildings (polygons), and in attribute table contains number of buildings, floor area of buildings etc. I would like to know how many buildings (#) is per Ha or km2, and building area ...
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19 views

Kernel Density Estimation Weighting Factor

I dont understand where is this weighting factor coming from, does it need to be in the quakeLyr in the attribute table named with "mag" or? ##Now, we can run the kernel density estimation algorithm ...
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37 views

Converting line vector layer to raster with pixellate.psp creating missing data?

The following example converts a line vector layer (road network) into a density raster. It seems to be working for others, but it looks like it's creating data gaps at my resolution (50m). library(...
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34 views

Multiplying individual raster layers by corresponding values in Excel file?

I have two groups of items I want to multiply, using the Times tool. I have a geodatabase full of density raster layers. I also have an excel sheet. This excel sheet has a column listing the names ...
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1answer
32 views

Converting Raster Density File into Point using ArcGIS Desktop?

I used the Point Density tool to create raster files. I plan on scaling these density values by dividing them by the greatest density value and then multiplying the result with a certain value that is ...
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1answer
120 views

Find EPS for DBSCAN

I have location posts from Instagram Data and want to cluster them by density - using DBSCAN. I played around quite a lot with different minPts and eps but never receive clusters (always one big ...
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25 views

Creating density map of roads for each district using ArcGIS Desktop?

I have to illustrate a map with the road density of each district. I have the city layer which comes with the bordered districts and another layer with all the roads. How can I create a density map ...
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30 views

Mapping density: Creating set range for multiple attribute tables

I have multiple attribute tables (for each state of a country) with data for population and area, and want to map population density. The standard way to map density (example below) automatically ...
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26 views

Modification of Line Density using ArcGIS Desktop?

I am using ArcGIS Desktop 10.1. I need to calculate Line Density for polyline vector but the "Search radius" option must be replaced by something like the Neighborhood option in Focal Statistics. I ...
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Calculating route length per grid cell using fishnet

I have a problem determining the length of the routes (boat) I've surveyed in order to calculate the survey effort. I added the GPS points of the boat and then used the points to line tool and added a ...
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1answer
51 views

Site density related to river vicinity

I use ArcGIS 10.1. I have a shapefile with sites and another with the rivers of the area. I would like to calculate the density of the sites related to the river vicinity. Is it possible? Which type ...
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1answer
94 views

Identify most densely populated areas along streets with QGIS

On Google Satellite Imagery, I've created a layer with objects marking houses in a 1 km proximity to large streets in a rural setting using QGIS with the Openlayers Plugin. I would like to identify ...
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1answer
82 views

Finding output values of point density calculation?

I ran the point density tool and got an output, but because the 'Area Units' option in the Point Density was locked to Square_Map_Units - I don't know how to tell what units the density was calculated ...
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1answer
242 views

OpenLayers - Dot Density map

I'm trying to create a dot-density map with OpenLayers (OL) and GeoServer. I've a counties shapefile and I'm creating a vector layer in OL with county shapefile set as source for the vector layer. I ...
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2answers
292 views

Density map of pedestrian paths and footways in QGIS

I need to identify public places within pedestrian areas in London, so I need to calculate the density of both pedestrian links and footways. I have classified my data according to the categorization ...
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1answer
511 views

Creating species richness map (as next stage after species distribution)?

I'm using ArcMap. I've read the messages related to this topic but they don't take me far enough. Most of the advice is related to species distribution, but I need to create a species richness map. ...
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2answers
151 views

Uncertainty of a line between two coordinates with uncertainties in QGIS

I am trying to plot the uncertainty of a line between two coordinates with uncertainties. I have created polygons around 2 coordinates to represent the uncertainty region around each point. I then ...
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1answer
91 views

Calculate density of point feature class using field calculator? (not pop)

I'm just wondering what would be the best method to calculate density in the field calculator for a point shapefile (ArcMap). This wouldn't be based on a population value. I would need to derive a ...
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2answers
540 views

Creating a population dot density map at the block group level in QGIS

I'm new to QGIS, always used ArcMap, and I'm struggling to find out how to best display population density at the block group level for a county (the most granular level of detail for census geography)...
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1answer
83 views

Creating linear density from points

I have a point layer from an aerial photographic survey of a savanna, where each point contains information on the number of trees found within each photo. Some points can have 0 trees, while other ...
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1answer
231 views

How can I set QGIS “Random Points” density to less than 0,0001 (circa 100 meters apart)?

I have an input boundary vector layer (700 hectares); on it, I want to generate a set of random points (Vector/Research tools/Random points) with a reciprocal distance average of 233 meters, but the ...
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147 views

Calculating built-up density for each cell in vector grid in QGIS?

I have two layers: a raster of India showing built-up areas (black pixels represent built areas) and a vector grid overlaying it. My goal is to calculate the percentage of built-up surface in each ...
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1answer
698 views

What does “layer units” mean?

I created a Shapefile from Google Earth (kmz) consisting of a set of points which I had used as a layer for Heatmap analysis. I opened the kmz file in QGIS and utilized the heatmap plug-in and it has ...
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88 views

Applying mask to Kriging shape in ArcGIS Desktop?

I'm trying to apply an mask to a Kriging image for after apply a Density Sampling Network, but unfortunately I'm not getting good results. I tried to apply on mask on Density Sampling Network and is ...
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How to interpret v.kernel network results

v.kernel "Optionally generates a vector density map on a vector network." I have done this for a network, but I don't understand how to interpret the output of this. Can anyone explain this? I am ...
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1answer
66 views

How can I transfer the values of a grid of smaller polygons to another grid with larger polygons in ArcGIS?

I have a population density grid containing 100x100m polygons. I would like to transfer the density values into an existing overlaying grid of larger polygons (250x250m). This might of course include ...
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3answers
2k views

Doing heatmap from line data in QGIS?

I want to perform a line density analysis for my line data, based on an attribute. The heatmap option (kernel density analysis) seems to be only possible for point data. I have tried to convert my ...
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1answer
359 views

Find average density value within a polygon in ArcMap

I've created a point density heat map for a city intended to show areas where there is more or less access to a certain type of public school. It would be useful to be able to identify which local ...
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1answer
96 views

Kernel Density Map points rejected as outside window

I am trying to make a kernel density plot of a points shapefile like so: library(rgdal) library(spatstat) library(maptools) points <- readOGR(dsn = "C:\\Documents", layer = "...
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1answer
663 views

Build Density Map for large dataset

I've got a postgre/postgis database with about 120 million positions (geography type). I would like to create a density map (e.g. a heatmap) and serve this via geoserver. I did create a one-band ...
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248 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 ...
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1answer
797 views

Finding outlier point in set of points, by distance, using QGIS?

I need to identify and eliminate the outlier points in a set of points, as depicted below. It seems a simple task, but I cannot find the answer anywhere. I suspect that the proper way to go is ...
2
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317 views

Identifying activity places in GPS trajectories using R?

Is there a way in R (a script or package) that would allow identifying activity spots in GPS tracking data? I have a number of GPS tracks in GPX/CSV formats that follow the movements of people in a ...
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1answer
366 views

Understanding Drainage Density?

I have calculated drainage density for two watershed and need to make sense of the numbers. One watershed has a drainage density of 1.08 km/km2 (area=32 sq. km and total stream length=34.436 km). The ...
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2answers
476 views

Getting quantity of intersecting lines of polygons in QGIS?

im looking for a way to get the quantity of lines from a line-layer that intersect the different polygons of a polygon-layer; I have: One line-layer with a clutter of lines, defined by ID, which ...
2
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1answer
73 views

Method for Spatial Analysis of Raptor Predation

I currently have presence data on two birds, a falcon species and the grouse that it prefers to hunt. These data are in two point shapefiles, one for each species. The grouse shapefile represents all ...
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159 views

ArcGIS - Point Density with Geocode data - not working

I would like to create a simple density map based on a geocoded data but the output shows up as blank. Below are steps I took: Add data - Import raw data based on Excel which has postal code (field: ...
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1answer
2k views

How to create a population density heatmap from attributes

I'm working with a point shapefile representing the municipalities of a country. Each point has an attribute that shows the population of the given municipality. Is it possible to map this attribute ...
0
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1answer
86 views

Displaying density map in ArcGIS Desktop?

I am using a shapefile from the European Commission on world maritime traffic. They have developed a map of maritime traffic as shown in the comments. I would like to replicate the same map that I ...
4
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1answer
857 views

Calculate Density in QGIS

I have a task where I need find the density of building footprints. I have a vector layer consisting of building footprints in polygons. To find the density I was thinking about drawing a set of ...
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1answer
266 views

Scatterplot derived from lat/lon data and census block group

The Guardian plotted homicide locations on top of city maps here: https://www.theguardian.com/us-news/ng-interactive/2017/jan/09/special-report-fixing-gun-violence-in-america Given lat/lon data for ...
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1answer
103 views

Centroids highest density areas

Is there a way to find the centroids of highest density areas in the density raster (red areas in the figure) created with the Optimized Hot Spot Analysis in ArcMap10.3. Theoretically I think I should ...
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62 views

Point Density Percentage Changes

I'm hoping to find out the methodology for mapping increases and decreases in point based occurrences from multiple tables. Eventual output: A map displaying point density/kernel density increases ...
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1answer
146 views

Density map based on polygon layer

I have a polygon shapefile representing a certain feature (e.g. irrigated crops) over a study area. I want to produce a density map for irrigated crops based on a reference square grid (e.g. 1X1 km). ...
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2answers
423 views

Calculating density map of cycleways using fishnet in ArcGIS Desktop?

How can I calculate density map of cycleways (line feature) which refers to net grid in ArcGIS? Result by using function Line Density in ArcGIS for me is not satisyfing. I created reference grid net ...
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1answer
357 views

Trying to measure point density along a line

I have a dataset that consists of animal sightings along a road and I want to calculate the density of points (sightings) along that road. My primary goal is to measure sighting hot spots, but I also ...
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2answers
642 views

Where do I get data for density per city in the USA or Europe?

Basically I need the data this infographic uses, the density per city or better yet per km square. USA or EU is indifferent, need it for a project.
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132 views

Calculating density using information linked to polygons?

I'm fairly new at GIS and am using ArcMap to calculate the population density of lizards on an island. On our island, we have about 80 trees, and each tree is mapped as a polygon on a single layer. We ...