Digital Geography

28. August 2015

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 general principles of work with the OpenLayers 2.x library can be applied with some adjustments to the work with the OpenLayers 3.x library, if for example, while creating some new objects replace the “new OpenLayers” to “new ol”, but this is not tested and I have not put currently such a task. As for me, the author of OpenWebGIS, it is enough in my work to use OpenLayers 2.x. But adapting the entire project on the base of the OpenLayers 3.x library can be very labor-expensive. (more…)

27. December 2012

QGIS Plugins — OpenLayers

Click for previous article in this series about RasterCalc

How often have you been working on a project in QGIS and wanted some nice background imagery, perhaps for a quick and dirty evaluation of your own data? I find I need this with growing frequency and a great way to do it is through the OpenLayers plugin for QGIS. Of course, if you know of a good WMS for your area of interest you can always go that route, but the OpenLayers plugin is a great addition to your QGIS toolbox.

The OpenLayers plugin is available through the official QGIS plugin repository HERE.

You can install by simply adding it to your plugins directory, as described in a previous post, after downloading and unzipping. Select the plugin (if necessary) in the Plugins->Manage plugins … menu, as seen below.

Once the plugin is selected, it can be accessed through the Plugins menu, as seen here:

From this menu, you can select which of the available layers you want, depending on your needs. As a quick example I loaded an orthomosaic for a small area around Nome, Alaska. The imagery for this mosaic was collected using a small unmanned aerial vehicle and the mosaic was georeferenced using only the onboard GPS data. Of course, these GPS data are not always entirely reliable and I wanted to see how close the product was, so I loaded up OpenLayers and was able to quickly see that it was close enough for my needs. The initial dataset is seen below:

Orthomosaic generated from UAV data for the area offshore of Nome, AK with no background layer

The same dataset after the Bing Aerial layer was added using the OpenLayers plugin.

Orthomosaic generated from UAV data for the area offshore of Nome, AK with Bing Aerial background layer

Clearly, my mosaic is reasonably close, even given the change in season. I’m finding that I use this plugin more and more in my daily workflow and I hope you find it useful too. Thanks for reading.

16. July 2012

a web-map with OpenLayers (part 3)

In the first two parts in our series on “getting to know openlayers” we concentrated on the question on layer consumption in form of basemaps and labels. We will enhance this a little in this tutorial. First of all we will use the famous modis products to serve our webmap, we will adjust the visible area of our web-map, set different parameters regarding the initial look and feel of our web-map and distribute it through our webpage. if you are not familiar with the initial frame in our html-document see this page.
First of all we will use this famous blue marble image set as our basemap: (more…)

29. June 2012

a minimal web-map using OpenLayers (part 1)

Web-mapping is used everywhere since GoogleMaps and GoogleEarth revolutionized our topographical and geographical perception. Keeping that in mind it is useful to get some insights in web-mapping possibilities.
An easy-to-use open source application for that is a javascript library called OpenLayers. You can run this on your local Windows or Linux machine easily: Download it from the OpenLayers website or if you are using Ubuntu as your Linux distribution just search for “openlayers” in the Software-Center or use your terminal:

sudo apt-get install libjs-openlayers libjs-openlayers-doc

But for a real minimal example you will only need 2 files in a folder: the openlayers.js and a index.html file. (more…)

6. February 2018

Short Announcement: OpenWhateverMap

Choosing a basemap for your cool web map is always crucial for the style and perception of your map. A colorful basemap like watercolor might be stunning but also interfering with your data visualization. In contrary a grayish basemap might look a bit boring but your data visualization will be crucial. If you’re unsure and a playful type of developer: Use OpenWhateverMap! (more…)

22. December 2016

Geospatial cloud solutions: Software-as-a-Service vs Roll-your-own

Over the last couple of years, we have seen an increase in demand and offerings of geospatial solutions in the cloud for tasks like web map creation, centralized data storage and management, data vizualization and so on. There is a lot of Software-as-a-service (SaaS) options to explore, but in this article I want to briefly discuss if SaaS is the right thing for you, or wether you should look into rolling your own. (more…)

20. October 2016

QGIS and basemaps: QuickMapServices

To work in QGIS is very often much more convenient if you can use a basemap for your data. In the past we used and promoted OpenLayers plugin quite often but this was not the best out there as you saw often some issues with projections as well as with “lost tiles” in the map composer. So here is the new weapon of choice: the QuickMapServices plugin for QGIS. (more…)

19. October 2016

Map your CV

Probably everyone at least once in your life was searching for a job and had faced the challenge of creating an interesting resume. But when you start to create a normal list-like cv/resume you will surely say “BORING! Next!”… As I’m a geographer the idea was to create map that is the CV itself. (more…)

3. March 2016

Python and Webmaps: folium

We have seen some easy ways to create webmaps without learning JavaScript or loosing sort of control of our data in terms of using a platform like cartoDB, mapbox or AGOL (ArcGis OnLine). There are R and QGIS connectors which translates your current data and project to a leaflet or openlayers based webmap. Today I worked with folium which creates a webmap directly from Python. Follow me! (more…)

10. September 2015

Webmaps with R: the leaflet package for R

Some months ago I published qgis2leaf which enables a QGIS user to publish a webmap the easy way. It was integrated into qgis2web which offers a leaflet and a openlayers based output for qgis users. But what about R users? Jean-Francois recently published a longer post about GPX tracks and to publish them using some heavy coding. So let’s welcome leaflet for R: an easy leaflet webmap exporter. (more…)

24. August 2015

Awesome map style

Are you back from holiday? Maybe you switched from Casale Monferrato, Piedmont and have used the map of Monferrato Landscapes. If you were lucky, you see a new update, I’ve made ten days ago, otherwise I invite you to go to review … but before I tell you how it was created. (more…)