Numa Gremling

Numa Gremling is a senior developer at geoSYS (Germany) where he leads various projects, most of them related to web mapping or QGIS plugin development. He is the author of the Leaflet Cookbook (Locate Press).


Leaflet: getting started with web mapping the easy way!
Numa Gremling

Leaflet is currently one of the most popular libraries to create dynamic web maps. But why? The answer is simple: because Leaflet is easy to use, avoids unnecessary complexity, and still offers all of the functionality that any modern web map needs. In this workshop you will learn anything that you need to know to get started with Leaflet. In just a few hours you will know how to create a web map, even if this is your very first contact with web mapping.

Topics include:
- creating an HTML template
- creating a basic web map
- adding various basemaps
- adding markers, lines polygons
- interactions (zoom, pan, etc.)
- introduction to GeoJSON
- converting any file-based vector format to a format readable by Leaflet
- event handling (e.g. getting the coordinates of a click on the map)
- if time allows: overview of more complex topics (e.g. connecting to a PostGIS database etc.)

This workshop is taught by the author of the Leaflet Cookbook - Recipes for Creating Dynamic Web Maps (Locate Press 2019).

Use Cases and Applications
Browser-side geoprocessing with Turf.js and Leaflet
Numa Gremling

This workshop teaches how to use the JavaScript library Turf.js to execute client-side geoprocessing tasks. Browser-side geoprocessing is an alternative to using Web Processing Services (WPS), which require a complex server-side infrastructure and which take longer to return results, even for trivial tasks, and whose setup requires a considerable set of skills and necessary user permissions. Turf.js is a pure JavaScript library, meaning that anyone with a basic knowledge of JavaScript can get started quickly. Turf.js is very well documented, flexible, and user friendly. It offers a multitude of geoprocessing tools, covering all the classics that are used in every desktop GIS software (e.g., buffer, erase, intersect, merge) and many advanced features.

During the workshop a variety of examples, as well as live coding, are shown using Leaflet as a mapping client, but participants will also be shown how to use Turf.js with OpenLayers. Participants will first be taught how to set up a simple map and then will be walked through preparing datasets from various formats (e.g., KML, GPX, Shapefile), so they can be used with Turf.js, which requires GeoJSON as input. This will be followed by the presentation of various tools, as well as the combination of them, to conduct meaningful geospatial analysis and queries, whose results can be displayed and exported.

This workshop is taught by the author of the Leaflet Cookbook - Recipes for Creating Dynamic Web Maps (Locate Press, 2019).