Author Archives: Alberto

Pearson correlation and GIS

Do these two variables have a correlation?. To answer this important question first of all we have to know that only if it’s a linear relationship and there are no outliers we can take advantage of Mr Pearson’s correlation statiscal tool. If i love chocolate, does this mean i have tendency of being chuby? orContinue reading “Pearson correlation and GIS”

Comparing France Meteo and Spain Meteo from the visualization point of view

After living in France for four years i have to tell i am always aware of Meteo information on TV (well, i live in Brittany, i guess this makes sense!). It was the same in Spain or anywhere else in the world where i had lived and the reason why is i have always lovedContinue reading “Comparing France Meteo and Spain Meteo from the visualization point of view”

Remote Sensing, Photogrammetry, Lidar and Landuse IGN Spain

A few more lines for leting you know again that i passed this other course just now in Instituto Geográfico of Spain (IGN). Remote Sensing, Photogrammetry, Lidar and Landuse, a comprehensive 40h update on relevant information i need tu use on a daily basis. This ‘update’ helps me to better understand what i am working with andContinue reading “Remote Sensing, Photogrammetry, Lidar and Landuse IGN Spain”

Advanced Thematic Cartography IGN Spain

A few lines for leting you know i passed this course last year 2013 in Instituto Geográfico of Spain (IGN). Spatial analysis, Spatial stats, proper simbolization, data mining and geovisualization. A very interesting 40h online course that helps me on a daily basis to be able to show geodata in a more professional way. BecauseContinue reading “Advanced Thematic Cartography IGN Spain”

HTML High resolution DTM visualization using QGIS

This QGIS Plugin, Qgis2threejs, exports terrain data, map canvas image and vector data to your web browser!! All you have to do is opening the DTM in QGIS (2.4.0 Chugiak), go to plugins library and install Qgis2threejs. Once its installed you will see this icon on screen and you will need to clic on it. ThenContinue reading “HTML High resolution DTM visualization using QGIS”

DTM from SRTM? Let’s compare sources using RMSE (Root Mean Square Error) and a gaussian kernell density map

I guess we all can make a DTM out of many sources but SRTM is one of the most common ones, right?. Then let’s learn from this very simple approach how close we are from the SRTM raw data. Selecting a not very big representative area to be able to handle it, exporting raster to polygon (fromContinue reading “DTM from SRTM? Let’s compare sources using RMSE (Root Mean Square Error) and a gaussian kernell density map”

La geografía española (con minúsculas)

Aquí la ‘convesación’ via twitter con el presentador de TVE Jacob Petrus. Me quejé de que se mencionara dentro de una frase, como tantas veces hemos oído, en radio y televisión, la expresión ‘La geografía española…’ refiriéndose a España en general. Lo que me indignó fue que Jacob Petrus es Geógrafo además de presentador generalistaContinue reading “La geografía española (con minúsculas)”

‘Reality Checks’, also called ‘Ground Truth Tests’

Comparing all kind of Geodata (i.e 3D Buildings, DTM, DHM, DSM, Land Use, vectors,…) to background sources as Google Earth/ Bing, available sources from the country we are working on or WMS available sources, etc. Figuring out if the data requested and we want to deliver is consistent enough compared to the so called “Truth”. SomeContinue reading “‘Reality Checks’, also called ‘Ground Truth Tests’”

RSME comparing LIDAR data with a third party’s 3D dataset

I would like to share with you an easy analysis i have been working in the last days. I had a vector dataset of buildings and i knew how high they were (there was a field called ‘AGL’ or Above Ground Level) and a LIDAR 2m resolution dataset over the city of London. My aimContinue reading “RSME comparing LIDAR data with a third party’s 3D dataset”