Statistically, here is how you should go about doing a heat map:
1) Integrate point features. The idea of integration is to take points that should be considered coincident and merge them together as a single location. I like to use nearest neighbor analysis and use an appropriate value from there. (For example, when doing a crime heat map, I use the ...
I've done a bit of work on this in GeoTools/GeoServer by extending the Heatmap Rendering Transformation to support geometries other than points.
It's not finished yet, but you can get the feature branch from my repository on GitHub.
The screenshot is of GPS tracks from when I worked as a pizza delivery driver.
In ArcGIS, the easiest way to create a polygon layer with the count of overlapping features is as follows:
Run the Union tool on your source polygon layers. This will result in a layer with one feature for each area of overlap.
Add a new field to the layer created in Step 1, called NewID or something to that effect, and use Field Calculator to set it ...
A good article from ESRI called "Extending your map with spatial analysis" explains and give examples of both.
Another good article, "Heat Maps in GIS", found over on GIS Lounge, shows that these terms can sometimes be used interchangeably.
I think the first paragraph of the article gives a great explanation of the term(s):
Heat mapping, from a ...
Step-by-step for GeoServer. Note: As @michal-mackiewicz writes, the WPS extension for GeoServer must be installed.
Acquire some point data, for example Natural Earth populated places http://www.naturalearthdata.com/http//www.naturalearthdata.com/download/10m/cultural/ne_10m_populated_places.zip
Import data into Postgis for example with ogr2ogr
ogr2ogr -f ...
Knightshound's answer is correct. Another option, if you don't want to create yet another file and keep ti always updated, is to use Virtual Layers. I'm not sure if Virtual Layers is available in QGIS 2.12 though.
Click add Virtual Layer button
Enter the following SQL query
select geometry from senders
select geometry from receivers
What you are actually trying to do is a kind of Location Allocation analysis. The need for a pharmacy is determined by two things:
The amount of people living in an area (amount of buildings is proxy)
The distance (either Euclidean or drive time)
You could use the freeware of Utrecht University; flowmap for this purpose. It is a bit 'clunky' though. Their ...
I created a simple python script for converting geohashes to 3d Google Earth representations. This isn't exactly what you asked for, but if you'd like to create a cool looking thematic map (based on geohash) this will get you started.
You can get the code on github here:
Heatmaps and interpolations are completely different things though they might look similar.
A heatmap visualizes "hotspots" in the distribution of features on the map i.e. dense areas will be highlighted in a heatmap, based on the parameters you use for processing it.
However the purpose of an interpolation is to estimate feature values at locations where ...
If your data consists of points and you would like to create a heatmap, QGIS has a handy heatmap plugin. There is a great tutorial on creating heatmaps from point data here.
Often it is useful to display categorical data in your maps. In this case, I would recommend using the integrated QGIS ColorBrewer located in the style manager. There is a great ...
Yes, the Heatmap plugin can be used for this.
Suppose we have a point layer called pointrates.shp with rates between 0 and 1 associated with each point:
We can run the Heatmap plugin on this, using a Decay Ratio of 1 (which means that the value at the edge of each search radius is the same as at the center), and using the "Ratio" column as the Weight. In ...
Found the answer myself. Check pixel size of raster, then calculate:
sum(point.value for point in circle) / (radius * radius * pi)
Where radius is in pixels (radius / pixel size), and value is what it should be (if all points are in radius, then sum, if only one, then that point value). Select "info tool" (top left on the screenshot), click on respective ...
Here's my approach for making a more generalized heat map in Leaflet using R. This approach uses contourLines, like the previously mentioned blog post, but I use lapply to iterate over all the results and convert them to general polygons. In the previous example it's up to the user to individually plot each polygon, so I would call this "more generalized" (...
I've just learned that the heatmap plugin is not part of version 1.7, so if that's what you're using (like I am), it's not here for us to use it yet. If you're using the "trunk" version of QGIS the heatmap can be found under the Raster menu.
On using the heatmap plugin
This discussion should shed some light on how this plugin works:
the procedure in which pixel values are computed is explained in the Context Help. Its just a linear assignment, say for a buffer of 10 pixels, and decay of 0, the central pixel has a value of 1, 2nd from center pixel has 0.9 and so n upto the 10th pixel with ...
From what I can see in the pictures you posted, there is not much variation in the heatmap raster. Try decreasing the radius value to better preserve local variations.
Without seeing your settings, I can only guess that you set the radius to a value smaller than the cell size. That will obviously cause problems. Decrease the cell size but note that ...
This is expected behavior. The ESRI Maps for Office help references this:
Heat map layers and layers that are clustered cannot be shared to ArcGIS Online as a layer, but can be shared as part of a map. In the ArcGIS.com Map Viewer, the heat map layer displays as a point layer instead of rendering as a heat map.
You need to duplicate the same layer in the table of content, and do the following steps:
For the first layer, turn on Scale dependent visibility from Layer Properties -> General and set the scale of Minimum (exclusive) for example 1:1000,000 and Maximum (inclusive) 1:5000 and set the symbology to single symbol.
In the following images, I am using ...
The documentation says
Radius: Is used to specify the heatmap search radius (or kernel
bandwidth) in meters or map units. The radius specifies the distance
around a point at which the influence of the point will be felt.
Larger values result in greater smoothing, but smaller values may show
finer details and variation in point density.
So if your ...
If I understand your question correctly I have done something similar before; just had to remember what I did.
This will work if your polys are overlapping AND not the same layer. If they are on the same layer and it it is possible, move them to seperate layers, if you don't the target layer will just inherit one of the values.
The key process to use is ...
Use the Heatmap plugin. It is the icon with two yellow circles. You can get to it by either right-clicking somewhere on your toolbar and select from the popup menu of plugins or you can go to Plugins -> Manage Plugins.
You might want to create centroids for your grid of polygons, then and attach the weight value of the data with no exact location (located in a grid cell) to the centroids. This can be accomplished by:
Vector->Geometry Tools->Polygon centroids
Vector->Database management->Join attributes by location
That should give you the weights (from each polygon in ...
Thinking that you need heat maps rendered on the fly, I would go for these options instead:
Both LL and OL: http://www.patrick-wied.at/static/heatmapjs/examples.html
Some on-the-fly examples:
The only way I've thought about truly doing a heatmap and/or density map in PostGIS is to break down what density is really doing:
Create a grid of X cell size - this could be a vector dataset, rather than raster, and there are methods of doing this elsewhere on this forum
Determine the radius you want to look for points around each cell
For each cell, get ...
I am not familiar with Strava, but in QGIS you can use a combination of blending modes and draw effects to get a raster-like feel, similar to the image above.
You can find both of them in the Style Properties of your layer (blending modes are under Layer Rendering).
I was generating similar graphs due to some confusion over the CRS. Basically, you need to make sure that both your project and your vector layer are using the right CRS. I was able to fix this problem by doing the following:
Open the Project Properties menu and select "Enable 'on the fly' CRS transformation". Select "WGS 84 / World Mercator" as the CRS.
One of the best sources of administrative boundaries is Global Administrative Areas. I downloaded the Russian administrative boundaries and there are four shapefiles included with the zipped file of varying levels of administrative boundary detail. The attached image shows Russian administrative level 1 boundaries, which include autonomous provinces, ...
A kernel density for this size grid only takes a fraction of a second. Evidently, the problem is that v.kernel is processing every one of your three quarters of a million points with too much precision and detail.
Instead, first create a grid to represent the point data, possibly using a finer resolution to reduce the discretization error in location. (...
Maybe you can generate a set of random points into your polygons, there is a QGIS tool for that ? If you have overlapping polygons, then you have higher density of them in this area. Then use heatmap for the points. You would need to run several rounds to find optimal number of points, as result depends on that.
If your data shows distribution of some ...