Questions tagged [density]

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

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18
votes
6answers
10k views

What's the best way to produce a density map from weighted points in QGIS?

I'd really like to repeat the functionality of the ArcGIS Kernel Density tool - how could I do that? I would like to limit answers to easy-to-install free-and-open-source software – i.e. QGIS ...
13
votes
5answers
4k 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 ...
13
votes
6answers
6k views

Identifying true curves/arcs in ArcMap?

The only good way of creating circles in ArcMap is using true arc, (compound curves) but I need to convert those to vertex (densifying) because of a compatibility problem. I need info for geodatabase ...
12
votes
6answers
4k views

How do I make a heat or Choropleth map that uses polygons in QGis?

I've been playing around with the heatmap plugin for QGIS and I am wondering if it is possible to make heatmap with using a similar plugin/tool that uses polygons as well as points? I would like to ...
12
votes
1answer
10k views

Creating Dot Density Maps in QGIS?

Is there a 'friendly' way to create dot-density maps, where a polygon attribute data defines the number of dots (e.g. 1 dot = 100 ) using QGIS 1.7+? I say friendly because after a couple of hours ...
12
votes
1answer
2k views

How do you use GRASS's v.kernel?

I am flummoxed on how to use GRASS's v.kernel. I have a vector layer of around 2.5 million points. I want to make a heat map using v.kernel to show concentrations, since I have variable instances ...
10
votes
3answers
5k views

How to interpret GRASS v.kernel results?

GRASS manual reads: v.kernel - Generates a raster density map from vector points data using a moving 2D isotropic Gaussian kernel ... Ok, but how do I interpret the results? I understand that v....
10
votes
1answer
854 views

Creating Human Trafficking Heatmap in QGIS?

I'm trying to create a heatmap with about 325 points distributed around the city of Houston. (FYI Houston is a major human trafficking in the US: a title shared with LA and Atlanta depending upon ...
10
votes
1answer
1k views

Counting number of plants in area using images from UAV? [closed]

How do I count the number of pineapple plants in a 1-hectare block? I have heard of these algorithms but I don't know how to do it. I'm still a newbie of QGIS, ArcGIS and ENVI. I have the NIR, RGB, ...
9
votes
2answers
7k views

Creating heat map or density map from stacked polygons in ArcMap?

I have a polygon shape file that has many overlapping features. Each feature represents an area used by polar bears. So some of the polygons overlap and some don't, and there are separate clusters of ...
9
votes
2answers
13k views

Interpretation of ArcGIS Kernel Density legend parameters

In ArcMap 9.3 I've used Kernel Density to map various incidents, but the resulting shapefile doesn't display any units of measurement. Is there a good, not-to-technical source that would explain in ...
9
votes
2answers
3k views

What type of kernel density function does ArcMap use?

I know that there are several types of kernel density functions, such as uniform, cosine, Gaussian, etc. I was just wondering which one the "Kernel Density" functionality in ArcMap 10's Spatial ...
9
votes
2answers
4k views

Spatial statistics tools : clustering analysis on raster data

I've an apparently simple problem, but i can't find a clear methodology to use. I'm tasked to delimit "urban areas" by vector convex polygons, using the Gridded Population of the World dataset from ...
9
votes
1answer
978 views

Creating contours with meaningful values from point data

I recently obtained a CSV containing the locations of all recorded bicycle accidents in Boston over the past few years. As an avid cyclist, I'd like to create a simple contour map that draws attention ...
8
votes
4answers
8k views

Heat map / Density map from dynamic points table in MapServer (GeoServer)?

How can I create a heat map (some would call a density map) from a points layer in MapServer (or GeoServer)? (preferably able to choose Interpolation method, NN, IDW, etc and color map with a ...
8
votes
3answers
12k views

Is population density considered continuous data and why?

Population counts are typically referred to as discrete or quantitative data. Why is population density a continuous data type when it is typically measured for aggregate areas such as census tracts ...
8
votes
2answers
3k views

Calculating Line Density in QGIS?

I have a map of fracture distributions over an area and I would like to calculate the density distribution of fractures that intersect a moving window with a specified radius. Is there a way to ...
7
votes
1answer
815 views

Normalizing and adding kernel density rasters

I have 4 years of road kill data for one road, though each year has a different sample time frame (i.e. May-June vs. April-October) and therefore each year has a different number of surveys and totals ...
7
votes
2answers
1k views

How to redistribute population data using Python in ArcGIS?

I am trying to redistribute population data from census centroids among to housing density. Would you please help me to do that? I do have census area centroids (points) and the boundaries belong to ...
6
votes
3answers
3k views

What is the highest resolution of population density data that I can obtain for USA freely?

Ok so as far as my understanding goes the most high resolution dataset available that factors in many other things (other than Census data ) at a 1X1 km resolution is Landscan data created by Oak ...
6
votes
2answers
311 views

Summing up over area based on distance related function?

Through a field study, we learned that the density of a bird species in the forest was related to the distance to forest edge: ln(density) = 1.89*(distance to edge) + 0.34 Now, for any forest polygon,...
6
votes
2answers
483 views

How do I compute v.kernel maps in less than 16 hours?

I am using the GRASS GIS 6.4.2 bundled with QGIS 1.8.0, using a PostGIS dataset exported via v.in.org.qgis from QGIS, to create kernel density maps. The layer has 738,288 points. My problem is the ...
6
votes
2answers
992 views

How to reduce points by proximity

I got a layer with over 4 million points. The distance between the points are 1 meter. How can i reduce the data so that no points have less than e.g. 10 meters between them?
6
votes
2answers
163 views

Line density for mulitple commuters in QGIS

I have a layer with multiple lines, one city area commuting to another. This means that on some roads there are multiple lines lying on top of eachother, which at some point will split. I also have ...
6
votes
2answers
785 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 ...
6
votes
1answer
894 views

Showing density of overlapping features via transparency in ArcMap?

Below is a famous map produced by the Facebook team, which shows the connections between their users. Where there are multiple overlapping features, the lines show more brightly, giving a clear ...
5
votes
1answer
801 views

Finding nodes with QGIS

As part of work in statistical mapping for school, I need to use QGIS to find the spatial extent of commercial nodes. A node is defined for this exercise as a zone of 75m in diameter where the ...
5
votes
1answer
3k views

How to produce density map in square kilometers?

I have a shp file with the location (lat, lon) of lightning spatial distribution. I want to produce a density map of lightning occurrence per square KM. I used density point function and I don't know ...
5
votes
1answer
5k views

How to do Kernel density analysis in QGIS 1.7?

Do someone have some suggestion? We would like to tray Kernel Density analysis as we did with ArcGis using QGIS?
5
votes
1answer
977 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 ...
5
votes
1answer
507 views

Adding kernel density output to map with ArcPy

I am trying to emulate the behavior of the Kernel Density tool from the ArcMap 10 GUI in a script; in other words, I want to calculate the density of a dataset, and add the visual result to a map. If ...
5
votes
1answer
1k 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 ...
5
votes
0answers
447 views

Search Radius for Line Density [closed]

I have been working with GIS for many years but I am fairly new to the spatial analyst side of things. I am working with many satellite tracks for many different individual animals and would like to ...
5
votes
0answers
713 views

Spatial join to kernel density / kernel density with polygon/point output in Arc [duplicate]

I'm looking for a way to join polygons to a density function for some other feature of interest. Current workflow make density raster from feature set of interest, using point/line/kernel density ...
4
votes
2answers
216 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 ...
4
votes
1answer
170 views

QGIS town label density

I'm composing a map of Big Island, Hawaii in QGIS 3.14.0 and would like to display major roads and cities + towns. Therefore I downloaded necessary information via QuickOSM. However, as many towns lie ...
4
votes
1answer
3k 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 ...
4
votes
1answer
1k 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 ...
4
votes
1answer
7k views

calculate building density in ArcMap

I have two questions related to calculate building density. I need to calculate the building density in a map which Data is in shape format. The buildings and the area are in two different layers. ...
4
votes
1answer
822 views

Finding intersection density for weighted lines connecting points across the continental USA [closed]

I'm working on an one-time problem that I'm hoping to solve with a computer program using free GIS libraries (preferably for VB.Net, C#, or Python... Java or C/C++ could work too). Alternatively, I ...
4
votes
2answers
1k 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 ...
4
votes
0answers
273 views

Building raster (population density) dependend diagram in QGIS

I'm using QGIS and trying to solve the following problem. I got 2 layers: population density raster point layer with the information about number of people could be hosted/served etc in this points. ...
4
votes
0answers
190 views

Interpolating species data from sample points in a small area [closed]

I have sample data from a small site (10 acres) which shows the number of occurrences of a particular species of snail over two sampling periods (fall and spring sampling). I want to try and ...
3
votes
3answers
1k views

Creating 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)...
3
votes
1answer
4k views

How to Calculate Utilization Distribution Overlap Index (UDOI) in ArcGIS Desktop?

I was wondering if any of you happen to have any information on how to calculate the Utilization Distribution Overlap Index (UDOI) in ArcGIS 10? If I understand it correctly the UDOI takes two kernel ...
3
votes
2answers
609 views

Choosing kernel density radius [closed]

I have 3 datasets with GPS points. Two of those are GPS points that represent boating activities (two different types) and the third represents turtle observations. I would like to perform Kernel ...
3
votes
1answer
661 views

Interpolating values within certain distance of points using ArcGIS Spatial Analyst?

Let's say I have a set of points representing bridges. I want to create a kind of "heat" map that would highlight areas within my study area that has many bridges in good or bad condition. I have a ...
3
votes
2answers
343 views

Quality estimation of a spline interpolation with barriers

I interpolated the age of minerals for the Inner Tien Shan mountains (Kyrgyzstan) using the ArcGIS tool "spline with barriers". I use ~ 200 points for my interpolation. The barrier that I use is a ...
3
votes
2answers
2k views

Determine density or cover from a raster layer that has been clipped by a polygon

I am a very new GIS user using ArcMap 10. I have a raster layer of tree canopy that I have clipped so that the layer is in a polygon that is a circle with a 2km radius. I have done this for four ...
3
votes
1answer
334 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 ...