Posts Tagged ‘DEM’

Comparación de DTM usando Global Mapper 17.0.1


Hagamos hoy algo sencillo, comparar, primero cualitativamente (visualmente) y después cuantitativamente dos DTM. Por un lado elegimos una fuente muy usual, SRTM de 3 arc sec (aproximadamente 90m) con un DTM derivado de Fotogrametría Stereo.

  • Comparación CUALITATIVA (i.e visual)
  • Comparación CUANTITATIVA (i.e RMSE)

Abrimos por un lado un DTM cuya fuente sea SRTM, en este caso me he conectado via WMS (Web Mapping Service) a través del data online disponible dentro de la misma aplicación Global Mapper (File/Download Online Imagery/data). La resolución es de aproximadamente 90m (3 arc sec).


Por otro lado he encontrado este DTM cuya fuente conozco (Stereo Photogrammetry). La resolución es de 5m.


A través de la herramienta ‘digitizer tool’ (Tools/Digitizer) seleccionamos una línea dibujada al azar sobre los dos. Botón derecho del ratón-> analysis/measurement/path profile. Exporto ambas imágenes (es importante en path setup definir un mismo mínimo y máximo para poder compararlas adecuadamente).

Con Photoshop superpongo (Layer display/ multiply) ambas imágenes y veo cuán diferente son.


Esto nos da una primera idea de la comparación, pero vayamos un poco más allá: ¿Cuál es el RMSE (Error medio cuadrático, Root Mean Square Error) entre ambas bases de datos?.


Esta es una medida de desviación que nos va a definir mucho más exactamente que una simple visualización. Podéis ver algo más desarrollado este punto en este link de esta misma página:


Ahora tan solo hemos de verificar que esta cifra sea la correcta teniendo en cuenta los valores de precisión prometidos en la entrega.

Espero que os haya resultado interesante, si así es, no olvidéis comentar, compartir o simplemente decir Hola. Cualquiera de estas opciones es apreciada.

Un saludo cordial,
MSc GIS and Remote Sensing


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 and this way, being able to properly describe it for my daily analysis,


County of Scotland (North Carolina, US) GIS Cartography


One more video  i recorded long ago on geoprocessing Cartography. Landuse, DTM, etc.
Hope you like it.


Creating DEM/DTM


It was 2007 when i finished my master’s degree and wanted to show some videos of procedures. At that moment in time i wanted to find a job -any job- involving GIS and i finally found it dealing with the Geovisualization department within a GIS company… now i happen to deal with DEMs. DTM, etc on a daily basis which is great!!. I hereby show you that video.

Hope you like it,



Data acquisition: How do I know if this river is been well acquired?


I’ve already entered my river but my imagery was in 2D so… was it well acquired?…  First of all, I import my shape (shp) file into Global Mapper (what a great sofware!) and export my vector file as a KML.

Import my river.kml file into my brand new Google Earth 5.2 or just double-click it in his location… easyest impossible!.

Select it and use ‘show elevation profile’,  a very useful new tool for these purposes…

And that’s it, constant altitude, almost perfect!.

Hope you have considered it interesting:-)



GIS+Architectural scenaries. Awesome!


Even from scratch or from dgn/dxf vectorial format’s contour lines you create your own scenario.

Then import your model previously created using Sketch-up (this time i used google’s 3d warehouse, thank you Dilbert).

Stamp your house using sketch-up sandbox tools.

Then fur your scenario as if it was grass…

A little of photoshop like clouds and thats it!

Alberto Concejal
geographer, 3d designer & 3D GIS technician
albertoconcejal [at]


Windmills (wind turbines). Geovisualization live!


I will do my best to build a 3d scenario incluiding a few wind generators located very close to Pancorbo Cliff, North of Spain, about 320 km from Madrid. As usual, I started getting a model from 3D warehouse and included inside my google sketch up session… after that it was just placing it in my GE scenario… That’s it!. Now a little bit of literature: 


The most modern generations of windmills are more properly called wind turbines, or wind generators, and are primarily used to generate electricity. Modern windmills are designed to convert the energy of the wind into electricity. The largest wind turbines can generate up to 6MW of power (for comparison a modern fossil fuel power plant generates between 500 and 1,300MW).


With increasing environmental concern, and approaching limits to fossil fuel consumption, wind power has regained interest as a renewable energy source. It is increasingly becoming more useful and sufficient in providing energy for many areas of the world.


One area where turbines have become feasible is in the Midwestern United States, due to great amounts of wind.


Source: Wikipedia


Hope you liked it.
BA Geography
MSc GIS and Remote Sensing
GIS Technician
albertoconcejal -at


Getting textures from Google Maps – Street View


I this post I am trying to show you how easy is adding a building to your scenario using textures from Google Maps (Street View). You have to know a little bit about Photoshop and layers and these stuff but it’s pretty easy thou…

First step, capturing my screen…OMG!!! there’s a tree in the middle of the building I want to model… there is no need to worry about it… Photoshop deals with it very well!!.




And after taking these three pictures I finally get this one (Thank you Photoshop!!!)… I could have done it much better but this is just for you to know the way to do it… its not that bad thou!


Second step: Start modelling… Im not teaching you how to model but I can tell you it’s a piece of cake… just try it. Of course I am using my beloved Google Sketchup. I get my current GE’s view:


Defining XYZ axes, first blocks… just starting dudes!…


Applying textures I had already got from Adobe Photoshop…



And after a few minutes modelling this is what I finally get:


Hey, It looks like more or less realistic!!!


Third and last step: Let’s go to Google Earth…



These two blocks of buildings are very close to where I live here in Madrid. Vicálvaro is 10 minutes to Madrid downtown by car… It’s far away but now it’s in your computer…cool, isn’t it?.

BA Geography
MSc GIS and Remote Sensing
GIS Technician
albertoconcejal -at


WMS in Google Earth.


I have thought there is something very interesting maybe you guys have never tried… using your Google Earth sesssion not just for navigating, finding your house or the place you are going on holidays to… If you use the WMS protocol to show your map over your 3D scenario you are going to add a little bit more of interest to your Google Earth… Lets add a Corine Land Cover Map over my 3D map…but, What is WMS???, What is Corine Land Cover???. Im not even trying to tell you by myself, I am opeining my WIKIPEDIA to tell you, hehe…


A Web Map Service (WMS) is a standard protocol for serving georeferenced map images over the Internet that are generated by a map server using data from a GIS database. The specification was developed and first published by the Open Geospatial Consortium in 1999.


CORINE (Coordination of information on the environment) is a European programme initiated in 1985 by the European Commission, aimed at gathering information relating to the environment on certain priority topics for the European Union (air, water, soil, land cover, coastal erosion, biotopes, etc.). Since 1994, the European Environment Agency (EEA) integrated CORINE in its work programme. EEA is responsible for providing objective, timely and targeted information on Europe’s environment.

This is the Official Corine Land Cover key map.


This is the area I would like to know more about, Chiclana de la Frontera in Cádiz, SW of Spain.


This is once we get connected via WMS to the place where you can get those maps ( By the way you can search on the internet to get more maps… you just have to go to google and search for ‘wms maps’ and you’ll be able to find them. This is a Corine Land Cover Map with information from year 1990.


This is a Corine Land Cover Map with information from year 2000.


This is what we find after comparing both images… I have compared them using Photoshop CSX but you can go further and use global Mapper, ER Mapper or ArcGIS… As you can see, those areas highlighed are the areas with changes (very small in this case)…


More geographic post to come very soon!!!



Modeling from scratch. Geovisualization live!


This is what we first have, a low resolution image taken from Google Earth (GE) visualization engine. This area is a small town within La Rioja, NE of Spain, about 300 km from Madrid. The town is called Muro en Cameros.


First of all we have to find a better resolution imagen beacouse is absolutely impossible geting the shapes of the buildings without a better one… I find it in the SIGPAC website (you can find a link by your right side->).


Let’s see the difference between these two scenaries…





Now, Let’s start modelling!!!!!. We open our Google Sketch-up (SU)…


We should clic on this icon to get our current GE view… Very easy as you can see… 


Now let’s start modelling… Isn’t it easy?????.


we will check it very soon!