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gisky: Don't use zonal statistics as a table in ArcGIS

OSGeo Planet - 15 hours 37 min ago
Short version: Don't ever use zonal statistics as a table in arcgis. It manages to do simple calculations such as calculating an average wrong.

Example of using zonal statistics between grid cells (from the ArcGIS manual)

Long version: I was hired by a customer to determine why they got unexpected results for their analyses. These analyses led to an official map with legal consequences. After investigating their whole procedure a number of issues were found. But the major source of errors was one which I found very unlikely: it turns out that the algorithm used by ArcGIS spatial analyst to determine the average grid value in a shape is wrong. Not just a little wrong. Very wrong. And no, I am not talking about the no data handling which was very wrong as well, I'm talking about how the algorithm compares vectors and rasters Interestingly, this seems to be known, as the arcgis manual states
It is recommended to only use rasters as the zone input, as it offers you greater control over the vector-to-raster conversion. This will help ensure you consistently get the expected results.So how does arcgis compare vectors and rasters? In fact one could invent a number of algorithms:

  • Use the centers of the pixels and compare those to the vectors (most frequently used and fastest).
  • Use the actual area of the pixels 
  • Use those pixels of which the majority of the area is covered by the vector. 

None of these algorithm matches with the results we saw from arcgis, even though the documentation seems to suggest the first method is used. So what is happening? It seems that arcgis first converts your vector file to a raster, not necessarily in the same grid system as the grid you compare to. Then it interpolates your own grid (using an undocumented method) and then takes the average of those interpolated values if their cells match with the raster you supplied. This means pixels outside your shape can have an influence on the result. This mainly seems to occur when large areas are mapped (eg Belgium at 5m).

The average of this triangle is calculated by ArcGIS as 5.47

I don't understand how the market leader in GIS can do such a basic operation so wrong, and the whole search also convinced me how important it is to open the source (or at least the algorithm used) to get reproducible results. Anyway, if you are still stuck with arcgis, know that you can install SAGA GIS as a toolbox. It contains sensible algorithms to do a vector/raster intersection and they are also approximately 10 times faster than the ArcGIS versions. Or you can have a look at how Grass and QGIS implement this.  All of this of course only if you consistently want to get the expected results...

And if your government also uses ArcGIS for determining taxes or other policies, perhaps they too should consider switching to a product which consistently gives the expected results.

Update March 18 2018: make sure you check out the comments from Steve Kopp (spatial analyst development team) below and the discussion - it is interesting.
Categories: OSGeo Planet

GIScussions: Mapping Google Sheets

OSGeo Planet - Sun, 2018-03-18 18:16

If you follow me on twitter you may have seen a few tweets encouraging you to donate to Linkey, a charity that provides support to rough sleepers by donors buying sleeping bags, cold weather gear and toiletry kits in their web shop. It’s an inspiring charity that only started a few months ago. I reached out to a couple of the founders to see if there was any way I could help them and in the midst of our discussions they asked whether I could improve the current map of the shelters that they support, they also wanted to be able to update the map easily as the list of shelters they were working with grew. “No problem, send me the list” I said, so last week I sat down with a small spreadsheet to see how I could knock up a slightly more elegant web map for them.

This is a screen shot of the map that they had on their site (I grabbed a copy so that it would be there as a reference point if Linkey subsequently uses one of the options that I offered).

This is an ok but rather basic map via a service from BatchGeo, which offers a neat copy and paste interface to drop some spreadsheet data and build a simple map. The letters on the pins correlate with a list of shelters and addresses that appears when you scroll the map down in the frame but it isn’t obvious that there is a scrolling option. One downside is the quite large advert that shows at the bottom of the map, you can get rid of ads if you upgrade to the $99/month “pro” option which offers a lot more features but is probably overkill for a charity that only wants to map 20 or 30 points at the moment.

First up I thought I would give QGIS and QGIS2Web a try (sort of reusing what I learnt on geocoding etc in making the US steel plants map a couple of weeks ago) which worked quite easily and produced

The downsides that I discovered with this map were that QGIS2Web support for SVG symbols (I had a nice “bed” symbol that I wanted to use for shelters) was a bit flaky, colours got lost, the OpenLayers version seemed to flicker or not appear (I couldn’t get to the bottom of this. Maybe I could have found a solution and spent some time tweaking to make the map more elegant but I also realised that the only way that the Linkey team would be able to update the map was by asking me to recreate it and re-upload to my server which was not an ideal solution.

I thought there should be a easy way to map a few points and produce some decent looking out put without going through the rigmarole that I had to geocode the point data, map it in QGIS, turn into a web map and then upload to my server. I did a bit of searching and stumbled on an add-on for Google Sheets called Mapping Sheets by The XS. This is a neat add-on which lets you select the address column for geocoding, choose a field for a filter to switch record groups on and off and then publish some GeoJSON to your Google Drive and create a map that calls this data.

Mapping Sheets is very easy to use (just make sure that GeoJSON is shared for public access within your Google Drive) and it’s also very simple to update, after you have edited the Google Sheet or added some rows you just open the add-on, rebuild your map and you are done. Downsides are that there isn’t a way to control the colours of the pins, change symbols or base maps and there is a limit of 50 rows in the free version of Mapping Sheets (the Premium version is only $25/year and gives more control over icons etc and unlimited rows). This is a pretty neat solution.

A bit more googling suggested that there was a direct integration between Google Maps and Google Sheets (as opposed to the map type charts that you can embed in a Google Sheet). Open Google Maps, log into your account, go to My places and select My Maps, create a new map (give it a title and description), add a layer by choosing the Import option and selecting your Google Sheet, select the address column and you are there, you have a map which you can now tweak by varying icons, colours and base maps.

Updating this map is a little more work than MappIng Sheets, once you have edited the Google Sheet you have to go back to My Maps and remove the old layer and add the layer again and restyle it. Plus side is there are no charges and there doesn’t seem to be a limit to the number of rows that you can map. I guess you pay your money (or not) and you can make your choice.

Both of these approaches work pretty well and don’t require any coding, web hosting or other tech competence. I’m sure ESRI have a similar solution using ArcGIS OnLine and MapBox offer a highly customisable solution but I think you would need to be better at JavaScript than me to get it set up. I guess you pay your money (or not) and you can make your choice.

BTW if this was useful, or even if it wasn’t, hop over to Linkey and buy something for some homeless people

Categories: OSGeo Planet

gvSIG Team: Creating a symbol library for gvSIG Desktop in a few minutes

OSGeo Planet - Fri, 2018-03-16 16:09

Although the symbol importer is available in gvSIG from some time ago not everyone knows it… and it’s a fantastic tool! Besides if we combine it with another applications like XnConvert we can create new symbology in a few minutes.

We are going to show an example, taking advantage of the fact that tomorrow is Saint Patrick’s Day, about how to create a symbol library related to that anniversary.

These are the steps to follow:

  1. We have to download the symbology (there are thousands of them in several websites like FlatIcon). In this case we search them writing ‘Saint Patrick’, we select the package and we download it in a zip file. Once downloaded and unzipped, we have it available for work.
  2. With XnConvert we generate a copy of those symbols to a smaller size. And a second copy, saved with ‘_sel’ suffix by applying a specific filter (in this case ‘negative’). In this way we will have some symbols that change to their negative version when we select them in gvSIG Desktop
  3. With gvSIG Desktop we use the symbol importer.
  4. The last step simply is to use them.

We have recorded a video where you can see how to do it in a few minutes.

Categories: OSGeo Planet

gvSIG Team: Crea en pocos minutos una biblioteca de símbolos para gvSIG Desktop

OSGeo Planet - Fri, 2018-03-16 13:53

Aunque el importador de símbolos hace ya varias versiones que está disponible en gvSIG Desktop no todo el mundo lo conoce…¡y es una herramienta fantástica!. Si además la combinamos con otras aplicaciones como XnConvert podemos generarnos nuevas simbologías en cuestión de minutos (muy pocos minutos).

Vamos a mostrar un ejemplo, aprovechando que mañana es San Patricio, de generación de una biblioteca de símbolos para dicha efeméride.

Los pasos son:

  1. Descargo la simbología (en webs como FlatIcon tenéis a millares). En este caso hago una búsqueda por el término ‘Saint Patrick’, selecciono el pack y lo descargo en un archivo comprimido. Una vez descargado y descomprimido ya lo tengo disponible para trabajar.
  2. Con XnConvert genero una copia de esos símbolos a menor tamaño. Y una segunda copia, guardados con ‘_sel’ como sufijo aplicándoles un determinado filtro (en este caso ‘negativo’). De este modo tendré unos símbolos que cambian a su versión en negativo cuando los seleccione en gvSIG Desktop.
  3. Con gvSIG Desktop uso el importador de símbolos.
  4. El último paso simplemente es…comenzar a utilizarlos.

He grabado un vídeo en el que podéis ver que en poco más de 3 minutos se hace todo el proceso.

Categories: OSGeo Planet

gvSIG Team: New plugin for analysis of drinking water distribution systems in gvSIG 2.4

OSGeo Planet - Fri, 2018-03-16 10:48

The new plugin to connect with the software called “Epanet”, that allows the analysis of drinking water distribution systems, is now available in gvSIG 2.4.

“Epanet” application is public and it’s developed by the United States Environmental Protection Agency (EPA).

“Epanet” performs extended-period simulation of hydraulic and water-quality behavior within pressurized pipe networks and is designed to be “a research tool that improves our understanding of the movement and fate of drinking-water constituents within distribution systems”. It provides an integrated environment for editing network input data, running hydraulic and water quality simulations, and viewing the results in a variety of formats. This helps to compute pumping energy and cost and then model various types of valves, including shutoffs, check pressure regulating and flow control.

To download this plugin you have to open the “Add-ons manager” (from “Tools” menu) and select the “Installation by URL” option, connecting to the URL by default. At the next window you will select “Hydraulic” option at the list at the left side, and you will mark the only plugin available. Then you will accept the rest of the windows (if you didn’t have the base plugin it will be installed too) and after finishing you must restart gvSIG so that the changes have an effect.

Once gvSIG is opened, you can access to the “HMachine” menu, where you will find the new submenu with all the options available.

At these videos you can watch more information about this plugin: “gvSIG + Epanet: data preparation” and “gvSIG + Epanet: run epanet”.

Categories: OSGeo Planet

gvSIG Team: Nuevo plugin para análisis de sistemas de distribución de agua potable en gvSIG 2.4

OSGeo Planet - Fri, 2018-03-16 10:48

Ya está disponible para gvSIG 2.4 el plugin para conectar con el software denominado “Epanet” y que permite el análisis de sistemas de distribución de agua potable.

“Epanet” es una aplicación de dominio público y está desarrollada por la Agencia de Protección Ambiental de Estados Unidos (Environmental Protection Agency; más conocida por las siglas EPA).

“Epanet” es capaz de trabajar con períodos de simulación sobre hidráulica y el comportamiento de la calidad de las aguas dentro de una red presurizada, además de estar diseñada para ser “una herramienta de investigación que mejore nuestro conocimiento del movimiento y destino del agua potable y sus constituyentes en una red de aguas”. Si bien fue diseñado para agua potable también puede ser utilizado para el análisis de cualquier fluido no compresible con flujo a presión.

Para descargar este plugin se debe acceder al Administrador de complementos (menú Herramientas), y seleccionar la opción de “Instalación por URL”, conectando a la URL por defecto. En la siguiente ventana seleccionaremos en el listado de la izquierda la opción “Hydraulic”, y marcaremos el único plugin disponible. Aceptaremos el resto de ventanas (en caso de no tener el plugin base nos avisará de que lo va a instalar), y una vez le damos a “Terminar” debemos de reiniciar gvSIG para que los cambios tengan efecto.

Una vez abierto gvSIG ya podemos acceder al menú “HMachine”, donde tendremos acceso al submenú “Epanet” con las nuevas opciones disponibles.

En estos vídeos podéis ver más información sobre este plugin (en inglés): “gvSIG + Epanet: data preparation” y “gvSIG + Epanet: run Epanet”.

Categories: OSGeo Planet

gvSIG Team: Crear un geoportal fallero con gvSIG Online y (menos de) 5 minutos de tiempo

OSGeo Planet - Fri, 2018-03-16 10:15

Hoy en una de las listas de correo de SIG se ha preguntado por un geoportal con información de los monumentos falleros (para los que no lo sepáis, estos días en Valencia son las Fallas, una fiesta que llena durante unos pocos días la ciudad de monumentos).

Aprovechando la consulta he probado el tiempo de creación de un geoportal de estas característicos con gvSIG Online.

Pasos realizados:

  • Descargar las capas del portal de datos abiertos del Ayuntamiento de Valencia: monumentos falleros, calles cortadas y barracas falleras.
  • Subir las capas a gvSIG Online, crear la leyenda.
  • Crear proyecto (geoportal) y publicar.

Tiempo empleado: poco más de 3 minutos. Todo ello con software libre y, tratándose de esta festividad…con tecnología nacida en Valencia.


Con unos minutos más se podría personalizar un tanto más, generar leyendas más atractivas,…pero el objetivo era generar este tipo de aplicaciones en menos de 5 minutos para contestar a un correo y compartir una información…y aún han sobrado un par.

Categories: OSGeo Planet

gvSIG Team: The Horton Machine, new geoprocesses available for gvSIG 2.4

OSGeo Planet - Thu, 2018-03-15 16:30

The Horton Machine” plugin, formerly known as JGRASS, is now available to be installed on gvSIG 2.4. This plugin has a new toolbox with hundreds of different geoprocesses, added to the more than 350 geoprocesses included in gvSIG Desktop.

With The Horton Machine in gvSIG we will have new and interesting tools: geomorphology analysis (drainage direction, network and watershed extraction, rescaled distances and hydrologic attributes, slope, curvatures, hydrologic indexes, geomorphologic attributes, statistics, peakflow, Saint Venant, tools to prepare data for HECRAS, Shalstab, debrisflow…), LESTO (LiDAR Empowered Sciences Toolbox Opensource), raster map calculator, mobile tools…

To download this plugin you have to open the “Add-ons manager” (from “Tools” menu) and select the “Installation by URL” option, connecting to the URL by default. At the next window you will select “Hydrology” option at the list at the left side, and you will mark the only plugin available. Then you will accept the rest of the windows (if you didn’t have the base plugin it will be installed too) and after finishing you must restart gvSIG so that the changes have an effect.

Once gvSIG is opened, you can access to the “HMachine”, where you will find the new toolbox with the geoprocesses.

During the 3rd gvSIG Festival there will be a presentation where the Horton Machine plugin management will be shown. It will be available from the “Communications” section at the event website from March 23rd.

Categories: OSGeo Planet

gvSIG Team: The Horton Machine, nuevos geoprocesos disponibles para gvSIG 2.4

OSGeo Planet - Thu, 2018-03-15 16:17

Ya está disponible para instalar sobre gvSIG 2.4 el plugin “The Horton Machine”, anteriormente conocido como JGRASS, que incluye una nueva caja de herramientas con cientos de geoprocesos de todo tipo, y que se suman a los más de 350 geoprocesos ya existentes en gvSIG Desktop.

Con The Horton Machine se tendrá acceso a herramientas para análisis geomorfológico (dirección de drenaje, cálculo de redes y cuencas, re-escalado de distancias y atributos hidrológicos, pendiente, curvaturas, índices hidrológicos, atributos geomorfológicos, estadísticas, flujo máximo, Saint Venant, herramientas de preparación de datos para HECRAS, Shalstab, flujo de escombros…), LESTO (LiDAR Empowered Sciences Toolbox Opensource), calculadora de mapas para capas ráster…

Para descargar este plugin se debe acceder al Administrador de complementos (menú Herramientas), y seleccionar la opción de “Instalación por URL”, conectando a la URL por defecto. En la siguiente ventana seleccionaremos en el listado de la izquierda la opción “Hydrology”, y marcaremos el único plugin disponible. Aceptaremos el resto de ventanas (en caso de no tener el plugin base nos avisará de que lo va a instalar), y una vez le damos a “Terminar” debemos de reiniciar gvSIG para que los cambios tengan efecto.

Una vez abierto gvSIG ya podemos acceder al menú “HMachine”, donde tendremos acceso a la nueva caja de herramientas.

Durante el 3er gvSIG Festival se dará una ponencia sobre el manejo de este nuevo plugin. Dicha ponencia estará disponible en el apartado de “Comunicaciones” de la web de dicho evento a partir del 23 de marzo de 2018.

Categories: OSGeo Planet

gvSIG Team: Plugins update for gvSIG 2.4

OSGeo Planet - Wed, 2018-03-14 11:44

After releasing gvSIG 2.4 version some improvements have been carried out on the behaviour of some plugins that were included on it. Through the add-ons manager they can be updated without installing gvSIG again.

In some of the improved functionalities it’s necessary to install more than one plugin.

These are the plugins that have been updated:


Name of the plugin to update (and build number)

Layout Document

  • Document: Layout document plugin, version 2 (BN 2.0.121-140)

Heat map legend

  • Document: Layout document plugin, version 2 (BN 2.0.121-140)
  • Vector legend: heat map (BN 1.0.14-17)

Point disperse geoprocessing tool

  • (BN 2.0.220-2767
  • (BN 2.2.92-2169)
  • (BN 2.2.92-2169)
  • (BN 2.2.92-2169)

Rossmo’s algorithm

  • Rossmo’s algorithm (BN 1.0.0-4)

Once you open the add-ons manager (“Tools” menu) you have to select “Installation by URL” option, connecting to the URL by default. Then you have to search any of the plugins for the concrete functionality, selecting and installing them (you can select several plugins at the same time). Finally you must restart gvSIG so that the changes have an effect.

Categories: OSGeo Planet

gvSIG Team: Actualización de plugins para gvSIG 2.4

OSGeo Planet - Wed, 2018-03-14 11:43

Tras la publicación de la versión 2.4 de gvSIG se han realizado mejoras en el comportamiento en algunos de los plugins que iban incluidos en ella. A través del administrador de complementos es posible instalar dichas actualizaciones sin necesidad de instalar de nuevo gvSIG.

En algunas de las funcionalidades mejoradas es necesario instalar varios plugins.

Los plugins que se han actualizado son los siguientes:


Nombre de los plugins a actualizar (y número de build)

Documento Mapa

  • Document: Layout document plugin, version 2 (BN 2.0.121-140)

Leyenda de mapa de calor

  • Document: Layout document plugin, version 2 (BN 2.0.121-140)
  • Vector legend: heat map (BN 1.0.14-17)

Geoproceso de dispersión de puntos

  • (BN 2.0.220-2767
  • (BN 2.2.92-2169)
  • (BN 2.2.92-2169)
  • (BN 2.2.92-2169)

Algoritmo de Rossmo

  • Rossmo’s algorithm (BN 1.0.0-4)

Una vez se accede al administrador de complementos (menú “Herramientas”) se debe seleccionar la opción de “Instalación por URL”, conectando a la URL que hay por defecto. Después se puede buscar cada uno de los plugins por su nombre e instalarlos (se pueden seleccionar varios a la vez). Finalmente, para que la actualización tenga efecto se deberá reiniciar gvSIG.

Categories: OSGeo Planet

GIScussions: FOSS4G UK, a personal view

OSGeo Planet - Tue, 2018-03-13 18:20

FOSS4GUK 2018 logo

Last week James Milner and his organising committee staged a brilliant FOSS4G UK at the Geovation Hub.

For the first time in ages I wasn’t organising a FOSS4G (well I did help with some financial bits and pieces), I wasn’t presenting (except for a lightning talk) so I could just hang out listen to interesting speakers and learn some cool stuff in the workshops.

Here is what I enjoyed in roughly chronological order):

Day 1

Joana Simoes

Joana Simoes of GeoCat gave the first keynote on SDI’s and containerisation – it sounds very techy but it wasn’t difficult to follow and gave a fascinating explanation of why you might want to use containers (in Joana’s case Docker) to create a highly scalable and simple to maintain infrastructure.

First keynote on #InternationalWomensDay at #FOSS4GUK by Joanna from @geocat_bv (cloug SDI as a service)

— Ross McDonald (@mixedbredie) March 8, 2018

The rest of the morning was filled with a QGIS stream which included “QGIS: A Sustainable Open Source Project” by Saber Razmjooei of Lutra, “Publishing MapAction Maps: A QGIS Plugin” by Ant Scott of Astun and MapAction and “QGIS Anywhere” by Martin Dobias of Lutra. As QGIS 3 starts to roll out, you cannot help but be impressed by the increasing ambition and professionalism of the project.

In the afternoon I sat in on Tom Armitage‘s brilliant “Data Visualisation with QGIS” workshop. I am a pretty basic mapper who can just about hack together some data in QGIS, this was a bit of an eye opener. Tom took us on a journey through some of those deep down dialogues – draw effects, layer and feature rendering settings, multiple styles, the Size Assistant. Those of us who managed to keep up made 3 or 4 pretty impressive maps and learnt a lot on the way. Somehow my maps weren’t quite as good as these:

Final prep for #FOSS4GUK
Training booklets ✔
Memory sticks ✔
Stickers ✔
Laptop ✔
Final power up ✔

You'd better come along to my talk to find out.

— Tom Armitage (@MapNav_Tom) March 7, 2018

Learning new viz-tricks in QGIS from @MapNav_Tom #FOSS4GUK

— Geogoeroe (@geogoeroe) March 8, 2018

Some quick images from the QGIS data visualisation workshop by @MapNav_Tom #foss4guk

— Tom Wragg (@T_Wragg) March 8, 2018

In the evening there was the now mandatory FOSS4G party at a local pub, great conversations, plenty of wine and beer and absolutely tons of food (much of which breached my healthy eating guidelines). Oh and we managed to get AC Milan vs Arsenal on the big screens so I was very happy with our first win ages.

A well-deserved drink at the Bowler Pub after a long but very good and insightful day at #FOSS4GUK

— Isa (@IsaUlitzsch) March 8, 2018

Day 2

Jorge Sanz
Day 2 started with a superb talk from Jorge Sanz of Carto. Once again it was technical but accessible and although it was based on the capabilities of the Carto product, Jorge emphasised that all of the code was open source and that you could build your own Carto stack rather than using their enterprise service. I’ve been a fan of Carto for a number of years and have proposed it to some clients as a solution. I signed up for a free entry level account a few years back which is a good thing because now they have gone completely enterprise and no longer offer free accounts (boo hoo) to new users. Still if you haven’t got a free Carto account the QGIS2Web plugin by Tom Chadwin is a great and simple free option.

My slides for "@CARTO as a Platform" talk at #FOSS4GUK

I had to cover a lot in 25 minutes, happy to answer any questions you may have

— Jorge Sanz (@xurxosanz) March 9, 2018

Next up was Thomas Starnes of the Royal Society for the Protection of Birds talking about “Open Drones”, this was a fascinating talk particularly for people like me who are so vector centric that we think imagery and 3D are just eye candy.

Great talk by @bio_carta from @Natures_Voice on their use of drones and software like @OpenDroneMap #FOSS4GUK

— Tom Armitage (@MapNav_Tom) March 9, 2018

Open slides from my #FOSS4GUK presentation 'Open drones: A free and open source workflow for the use of drone imagery in mapping and geospatial applications' using @3DRobotics #MissionPlanner @OpenDroneMap @OpenAerialMap @openstreetmap @WILDLABSNET

— Thomas Starnes (@bio_carta) March 9, 2018

Then it was off to the Lightning Talks session where I had cobbled together a few thoughts, more questions than answers, on the “Open Communities – we love to hate …”. The theme was that we tend to be tribal and sometimes we can lapse into fundamentalism all of which creates a tension within the community. Sometimes we are more united in our opposition to some other group or camp than we are in furthering our vision for our open community. The ideas are still forming and I plan to explore them further in a couple of talks later in the year (assuming the proposals get accepted).

#FOSS4GUK lightning talks. Are we welcoming, open, inclusive asks @StevenFeldman #gistribe

— Ross McDonald (@mixedbredie) March 9, 2018

And here's @StevenFeldman asking the right questions at #FOSS4GUK

— Geogoeroe (@geogoeroe) March 9, 2018

Lightning talks are being kicked off by @StevenFeldman and his very thought provoking stream of consciousness bullshit rant #FOSS4GUK

— Steven Ottens (@stvno) March 9, 2018

The afternoon session on visualisation was all round brilliant. First up was Charley Glynn of the OS introducing their GeoDataViz Toolkit which they have open sourced. This is a great resource with colour swatches, icons, workshops and loads more stuff.

Great work by @charley_glynn and the @OrdnanceSurvey DataViz team.. check out their carto toolkit #FOSS4GUK

— Ed Parsons (@edparsons) March 9, 2018

This slide would have had Ken Field on his feet cheering from the other side of the planet:

Nuff sed.#FOSS4GUK

— Ross McDonald (@mixedbredie) March 9, 2018

Oliver O’Brien dazzled us with a colossal collection of code snippets and tricks for OpenLayers

The triangular colour ramp map from @oobr. Whaddayatink?#FOSS4GUK

— Ross McDonald (@mixedbredie) March 9, 2018

Shout out from @oobr for UTFGrid: feature info without vector tiles #FOSS4GUK

— Edward Mac Gillavry (@emacgillavry) March 9, 2018

And then we were treated to another tour de force from Tom Armitage riffing on a Star Wars theme. The audience loved it.

@MapNav_Tom and the different composite operations. In @CARTO we have some old materials about this, products evolve but techniques remain. This differenciate technologists from technicians (or button smashers, as @Spatial_Punk likes to say) #FOSS4GUK

— Jorge Sanz (@xurxosanz) March 9, 2018

Who needs a laser pointer, when you can point out things with a light saber as displayed by @MapNav_Tom #FOSS4GUK

— Steven Ottens (@stvno) March 9, 2018

Check out, young padawan, and much you will learn from @MapNav_Tom #QGIS #FOSS4GUK

— Ross McDonald (@mixedbredie) March 9, 2018

Last up was Ross McDonald talking about the different ways to visualise thousands of individual journeys to school.

Using @blender can really turn your maps up to 11. OpenSource #FTW #FOSS4GUK @mixedbredie

— Tom Armitage (@MapNav_Tom) March 9, 2018

Data Driven #cartography from @mixedbredie using @postgis #FOSS4GUK

— Tom Armitage (@MapNav_Tom) March 9, 2018

Nice talk on 3D spidermaps with QGIS, PostGIS and Blender by @mixedbredie #FOSS4GUK

— Steven Ottens (@stvno) March 9, 2018


Peter Batty

And then to finish off the afternoon my good friend Peter Batty of Ubisense delivered the closing keynote on “Geospatial Industry Trends”. Peter is a brilliant presenter, makes stunning slides but most of all is always thoughtful and thought provoking. This talk was no exception. Early on we learnt about Ubisense’s use of open source at some of the largest telcos and utilities in the US

"Most of the open source software we've used has been so good we've almost never needed support" (and when there was a major issue it was fixed overnight) @pmbatty #foss4guk

— Ant Scott (@antscott) March 9, 2018

Then Peter compared the effort that has gone into creating OSGeo software with what it took to build the Empire State Building

OSGeo person years > Empire State Building

Who’d have thought?

Just in case the audience were feeling a little exhausted at the end of the two days, Peter strung together an amazing video collection illustrating where we might be in 5 or 10 yers time. He concluded with this provocative (deliberately?) slide

Wrapping up #FOSS4GUK with a future view from @pmbatty

— (((Steven Feldman))) (@StevenFeldman) March 9, 2018

And that was it, just time for James to wrap up

Lessons learnt at #FOSS4GUK @Geovation

— Isa (@IsaUlitzsch) March 9, 2018

I had one last push to get people to donate to the FOSS4G Travel Programme, during the 2 days we collected $440 to help people travel to Dar es Salaam this summer. You could add to that by clicking on the donate link

And then it was time to go to the pub for a last drink and to say goodbye to new and old friends from near and far until the next time we have a FOSS4GUK (rumour has it that FOSS4GUK 2019 will be hosted somewhere in Scotland next year).

All that is left is to say thanks to the wonderful sponsors who made the event so affordable and who contributed their staff’s time and energy


Apologies to all of the other speakers whose sessions I missed and haven’t mentioned, particularly my pals at Astun.

You don’t have to wait until 2019 to experience the FOSS4GUK goodness. Fortunately there will be several more opportunities this year including FOSS4GNA, FOSS4G France, FOSS4G Europe and of course the big one, FOSS4G2018 in Dar es Salaam.


Categories: OSGeo Planet

Fernando Quadro: 1º LIVE GeoEspecial

OSGeo Planet - Mon, 2018-03-12 20:33

O canal do Luis Sadeck no YouTube irá realizar sua 1º live, e pra esse evento vai reunir nomes como Anderson Medeiros, Felipe Sodré, Jorge Santos, Murilo Cardoso, Narcélio de Sá e este que vos escreve em um bate-papo para falar de assuntos diversos no dia 20/03/2018 as 20:15h. Faça já o agendamento para não perder esse evento!

Se você quiser deixar suas perguntas lá nos comentários do evento ou aqui na postagem, tentaremos responde-las durante a live.

Esperamos por você no dia 20 de março!

Categories: OSGeo Planet

GIScussions: Eating Humble Pie

OSGeo Planet - Mon, 2018-03-12 20:04


humble pie, smokin',

Last week I wrote a post about making a map of the locations of US steel plants and the electoral results in their local communities. I concluded with this brief summary

“it’s a first draft and needs a good bit of work, but you can certainly see a pattern – most of the steel plants (and all of the large ones) are in Republican Districts – hardly a big surprise but there you go. I guess big tariffs will play well with hardcore Trump supporters.”

Unfortunately I didn’t follow the advice that I gave to other mappers in my “FAKEMAPS, very dishonest” talk namely

  1. Dig deep into your data, is there really a spatial pattern in it? What is the best way to represent it?
  2. Try different settings and styles (and even projections) to see the difference in output before starting to refine your map
  3. Is your map showing the message that you want to get over? If so be very cautious that your own bias combined with settings isn’t producing misleading results
  4. Less is more, don’t try to map too many variables
  5. Pay attention to detail, it makes an enormous difference. Don’t make your map at the last minute
  6. Get some feedback from one or two colleagues (even an expert) before you publish

I messed up badly on this map particularly with regard to points 3 and 6

Categories: OSGeo Planet

GeoSolutions: A WFS 3.0 prototype in GeoServer; are we getting it right?

OSGeo Planet - Mon, 2018-03-12 15:00

WFS 3.0

Dear Reader,

Let us start with a word of caution, this is going to be a rather technical post on the new version of the OGC WFS protocol, so do not expect nice images but rather a technical discussion about protocols, formats and the like. Good news is that you will not see much XML which is 180 degrees change with respect to working with current OGC protocols; although “everybody loves XML” this will make a few people in the GIS community happy (hey JS developer… yes, I am talking to you…). So, if you still haven’t moved away from this post, let’s deep dive into this new creature we are growing.

Our GeoServer technical lead Andrea Aime joined the WFS 3.0 hackathon this week, together with a few well-known names in the OGC and FOSS4G community to build a WFS 3 core prototype for GeoServer, delivered as a community module and available to be tested online for the braves. In the following paragraphs we are going to give some quick feedback from this experience hoping that it will help others to understand where WFS is going as well as out OGC colleagues to keep pushing forward with this effort.

About WFS 3.0

The WFS3.0 core protocol is geared towards the web and simplicity: dominated by (Geo) JSON representations, only supports WGS84 in and out, it’s schema-less, and has limited filtering and paging abilities. Everything else you’re used to see in WFS 1.1 or WFS 2 will be delivered as extensions to the core, that implementors can decide to implement, or not.  The approach is similar to WCS, small core and various extensions, helps getting started implementing the protocol and it’s a lot of help when building custom servers.

Going back to core, the equivalent of a “capabilities” document is split into two, a “contents” document simply listing the available layers, and a “api” document, OpenAPI 3.0 in particular, describing the details of how calls should be made. Eventually, a last set of call can be made to get features, in one of the supported formats (GeoJSON, GML, HTML).

Implementing WFS 3.0 in GeoServer

We joined the hackathon with no previous preparation or code, everything was started from scratch in a new community module. Had it been a traditional OGC specification, implementing the required parts of the protocol would have been “mission impossible”.

Thankfully WFS 3.0 core is pretty simple, while still supporting the basic needs of web clients, and we could leverage some existing facility in terms of spatial filtering, paging and  GeoJSON encoding. Here are a few example links from the GeoServer prototype:

Mind you, those links should be only used to get a feeling, the community module is not a complete nor fully correct implementation of WFS 3.0 core. That said, a couple of experimental clients can already successfully extract data from GeoServer WFS 3.0, including the new GDAL/OGR experimental driver.

Conclusions and Feedback

Generally speaking, working on this WFS 3.0 prototype has been a learning experience (OpenAPI 3 wise, after documenting the GeoServer REST API with Swagger 2.0), and a useful change of pace that will help acceptance and usage of OGC protocols among the current generation of GIS developers, both client and server side.

As far as the protocol itself is concerned, we believe that in order to see this protocol performing in the real world there is still work to be done which might result into extensions to cover what follows:

  • Scalability towards thousands of layers or more, maybe with some way to filter the API document and paging support for the contents document
  • Sorting and random paging support. This is crucial to use this protocol with real world datasets from web clients.
  • CRS and reprojection support, for various reasons, such as relieving clients from reprojection (they could only be interested in web mercator), supporting national laws requiring published data in certain local CRSs, and making sure no un-necessary datum shifts are performed when high precision is required.
  • A CRS extension that clearly specifies axis order used by the server, without having to refer to an external database that may or may not be there. Also, bake that information in responses when possible.
  • Sophisticated filtering, but the easy way… can we propose Extended CQL (GeoServer's own variant) as a base for human friendly filtering? This is has been used and reviewed already in OGC TestBed 13 to implement seamless filtering across WMS, WFS and WCS services ad described in the Fit-for-Purpose Engineering Report.
  • Schema declaration for cases where data actually follows a fixed schema (a must have for build complex filters, too). An OpenAPI schema will do in most cases, but for more complex ones, provide allowance to use XSD (think INSPIRE schemas for example).

Long story short, WFS 3.0 is a step in the right direction that will help spread adoption of a service that has in the past been limited by its complexity. The OpenAPI approach, allowing quick and automatic generation of ad-hoc client libraries should also favour its usage and reduce time to market for solutions based on OGC protocols.

The rich functionality provided by previous WFS versions should however not be ignored, but properly managed into a set of clear and well known extensions. Also, the core should be kept supple and easy to extend, in order to favour the wide variety of vendor extensions out there, helping the best of them to be recognized and shared to the wider community, much like GeoPackage already does.

Last but not least, it is worth to point out that we will perform more work on WFS 3.0 implementation for GeoServer throughout 2018, including adding other extensions, so stay tuned and follow this blog for more info.

And now, since you have read so far, if you are interested in learning about how we can help you achieving your goals with open source products like GeoServerMapStoreGeoNode and GeoNetwork through our Enterprise Support Services and GeoServer Deployment Warranty offerings, feel free to contact us!

The GeoSolutions team,
Categories: OSGeo Planet

gvSIG Team: GIS applied to municipality management: Certification and links to the complete course

OSGeo Planet - Mon, 2018-03-12 09:40

The certification of the course about Geographic Information Systems applied to municipality management is now available.

This certification period is opened after the publishing of the last modules of the course, but it will be open continuously, so that any user can get it at any moment when they finish the different modules.

To get this certification, a complete exercise must be completed, which includes some of the contents given during the course. Likewise, you must have at least 7 of the 10 existing activities correctly.

The exercise will validate the knowledge acquired during the course and will be evaluated by a tutor.

Apart from the delivery and passing grade of the exercise, the certification will have a minimum cost, necessary to cover the expenses related to the evaluation and certification. This cost will be € 30.

The certification will be issued by the gvSIG Association, and it will consist of two certificates:

  • Course completion certificate, which will include all the information related to the training contents acquired.
  • Official gvSIG User certificate, having completed the 90 credits necessary for this, and which gives the right to get the gvSIG Expert User certificate, passing the credits necessary for its validation, through the courses offered by the gvSIG Association.

The dedication time of the course is about 90 hours.

The exercise to be completed and the cartography to be used can be downloaded from the following link:

The steps to follow to send the exercise, as well as to make the payment in order to get the two certificates are explained in the first section of the practical exercise in detail.

If you haven’t taken the course yet, you can follow the different modules from the following links:

Categories: OSGeo Planet

gvSIG Team: GIS applied to Municipality Management: Module 17 ‘gvSIG Mobile (Connection with gvSIG Desktop)’

OSGeo Planet - Mon, 2018-03-12 09:38

The video of the seventeenth module is now available, where we will show the integration between gvSIG Desktop and gvSIG Mobile.

From now the certificate of the course about GIS applied to municipality management is available too, following the instructions indicated in this new post.

As we watched in the previous module, gvSIG Mobile plays an important role in the city council management, since it allows us to carry out census, inspections, inventory… management.

From gvSIG Mobile you can manage the inventory of a municipality (litter bins, lampposts, children’s parks …), and if there is an incidence in any of the elements, it won’t be necessary to describe the element to the technicians. The citizens would be able to go directly with their mobile, and locate the lamppost or litter bin to be repaired on the map in an easy way.

In this video we will explain how to create an empty layer in gvSIG Desktop, adding new fields to the attribute table, and we will export it to gvSIG Mobile. With the mobile application we will edit that layer, creating new elements (we can create a point, line or polygon layer), with or without using GPS, and we also can edit its alphanumeric information. Finally, we will export it to gvSIG Desktop in order to perform a more complete analysis.

As we told in the previous module, gvSIG Mobile is available for Android, and it can be downloaded for free from the Play Store.

In order to exchange files between both applications we will use the Spatialite databases, functionality that is available from gvSIG Desktop 2.4.

In a few days there will be a new plugin for that version that will allow to export and import complete projects (with notes, pictures …) between gvSIG Mobile and gvSIG Desktop, as well as to export a tile layer from gvSIG Desktop (an orthophoto or vector file) to gvSIG Mobile to be inserted as background. During the 3rd gvSIG Festival there will be a complete demonstration about the use of these new features.

Here you have the videotutorial of this module:

Related posts:

Categories: OSGeo Planet

Gary Sherman: Where's my .qgis3 Folder?

OSGeo Planet - Mon, 2018-03-12 08:00

There's been several posts to GIS StackExchange along the lines of:

Where's my .qgis3 folder?

Prior to QGIS 3, the .qgis/.qgis2 folder was found under your home directory. At version 3, the folder has moved to a more standard profile location for your operating system.

There are a couple of ways to determine where the folder is located:

  • Use the Settings->User Profiles->Open active profile folder menu item
  • Use QgsApplication.qgisSettingsDirPath from Python or the console

Here are the "standard" locations for Linux, Mac, and Windows, as found under your HOME directory:

  • Linux:
    • .local/share/QGIS/QGIS3/profiles/default
  • Mac OS X:
    • Library/Application Support/QGIS/QGIS3/profiles/default
  • Windows:
    • AppData\Roaming\QGIS\QGIS3\profiles\default

To get the location of your plugins directory, just add python/plugins to the appropriate location above. For example:


From the Settings->User Profiles menu, you'll notice a New profile item. This allows you to have multiple configurations of QGIS 3. Each new profile is created in the same "base" location as listed above. For example:


Categories: OSGeo Planet

From GIS to Remote Sensing: Minor Update: Semi-Automatic Classification Plugin v. 6.1.1

OSGeo Planet - Sat, 2018-03-10 09:04
This post is about a minor update for the Semi-Automatic Classification Plugin (SCP) for QGIS, version 6.1.1.

This update is mainly related to Landsat preprocessing, in particular for the surface reflectance products.
Categories: OSGeo Planet

GeoTools Team: GeoTools 19-RC1 Released

OSGeo Planet - Fri, 2018-03-09 00:42
The GeoTools team is pleased to announce the release of GeoTools 19-RC1: maven repository As a release-candidate, 19-RC1 is not intended for production systems, however the API is stable and we invite everyone to try upgrading their applications, report any issues, and help out with the
Categories: OSGeo Planet
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