Digital Geography

Heatmap, JavaScript, Openlayers and canvas

This article is a continuation of the article “Heatmap and Interpolation: it is easy in OpenWebGIS” about creation of Heatmap and Interpolation with the help of OpenWebGIS interface. We are now describing the process of creating a heatmap, based on any point layer, using JavaScript, OpenLayers 2.x and canvas element (as part of HTML5 technology). Describing the process we will expect that you certainly already have some basic knowledge of programming language JavaScript and can handle OpenLayers library (which is an open source provided under the 2-clause BSD License) JavaScript library for displaying map data in web browsers.). Perhaps the…

Heatmap and Interpolation: it is easy in OpenWebGIS

In this article we consider the creation of Heatmap and Interpolation with the help of OpenWebGIS interface. In the next article it is planned to describe its technical implementation using JavaScript, OpenLayers 2.x and canvas element (as part of HTML5 technology). Recently, in an article “Some new (June 2015) features and functions in OpenWebGIS” it has been announced to revise the interpolation module completely. This promise has been kept, and at the moment in OpenWebGIS you can build a heatmap and make interpolation by the method of Inverse Distance Weighting (IDW). It is planned to add (if it is possible)…

QGIS 2.8: A Preview

QGIS 2.6 landed recently on this planet and it already brought great improvements to our daily work with geodata, the way we publish our results and the convenience in our workflows. But due to the very ambitious release plan of the QGIS core team and the great work of Klas we can have a look at the upcoming features in QGIS 2.8 major version already. Check em out:

create point density raster in QGIS

In some applications you want to calculate the density of points. It sounds very easy and in fact it is using QGIS. Let me show you how to create a point density raster. Especially, let me show you how to do this with the heatmap plugin in QGIS. Prerequisities You will need the common installation of QGIS 2.0.1 Dufour and an installed heatmap plugin (see how to install a plugin here). We will use some field data from Indonesia with 500.000 data points. You may download the data (12MB) we will use here. The doing Fire up QGIS and set…