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Posts Tagged ‘modelos digitales del terreno’

DTM validation using Google Earth (and RMSE extraction)

2015/03/10

Hi guys,

Surfing the internet is great when you need to figure out something. I needed to validate some DTM from unknown sources against an also unknown source (but at least a kind of reliable one, Google Earth).

All we need is

  • Google Earth
  • TCX converter
  • ARcGIS
  • Excel

This is the procedure i have followed:

  1. First of all we draw a path over our AOI using Google Earth, we save this as KML,
  2. This KML is opened by TCX converter, added heights and exported as CSV,
  3. CSV is imported by ArcGIS,
  4. We use the tool ‘extract multi values to points‘ to get in the same table the values of our DTM and the values from Google Earth,
  5. We use Excel to calculate the RMSE and get a quantitative result,

These are the values in our DTM

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This is the path we have to draw in Google Earth

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Using TCX converter we get the heights out of Google Earth’s DTM

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Using the tool ‘extract multi values to points‘ we get the heights out of our DTM

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We measure the differences and extract the RMSE.
Are we within our acceptance threshold or expected level of accuracy?.

You guys have to figure this out for yourselves!!!

Lost regarding RMSE calculation?. Think you have to take a look at this other post.

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Hope you guys have enjoyed this post, if so, don’t forget sharing it.

Alberto Concejal
MSc GIS and QCQA expert (well this is my post and i say what i want :-))

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Using Excel to calculate the RMSE for LiDAR vertical ground control points

2010/06/30

(source: http://dominoc925.blogspot.com/)

The height accuracy of the collected LiDAR data can be verified by comparing with independently surveyed ground control points on hard, flat, open surfaces. It is essentially just calculating the height differences for all the control points and then determining the height root mean squared error (RMSE) or differences. Most LiDAR processing software have the reporting function built-in. However, plain Microsoft Excel can also do the job (except for extracting the elevation from the LiDAR data).

Assuming that you are able to calculate the height differences for all the control points and place in a spreadsheet as shown in the figure below. I have a column of delta Z values in column A.

Then to calculate the RMS value for the elevation differences, I can do the following.

  1. In a cell, type in the formula:= SQRT(SUMSQ(A2:A18)/COUNTA(A2:A18))where A2:A18 are the values from cell A2 to A18 in the spreadsheet. Simply replace these with the actual locations on your spreadsheet.
  2. Press RETURN.
    The RMSE value is calculated.

(source: http://dominoc925.blogspot.com/)

Map24.com; My favorite route planner!

2010/06/03

My very good friend Fernando (a spanish/english like friend of mine:-)) introduced me this magnificent route planner he was using at that moment (three years ago!!!!)… map24.com had a very interesting 3D engine, very easy to use and very reliable… I’ve been using it since but it has never been one of the most famous among route planners in the market…

I strongly recommend it and i really like it a lot! enjoy!

http://www.es.map24.com/
http://www.map24.com/

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

More of my 3D video edited scenarios.

2009/08/16

Please, dont forget to turn on your speakers. Even if i first used a different score and Youtube’s elfs told me not to use it (because of copyright authoring) I have chosen this music from their stuff and this is what I finally got…

Hope you like it.
Alberto
BA Geography
MSc GIS and Remote Sensing
GIS Technician and Multimedia Designer
albertoconcejal -at -gmail.com

Some of my 3D scenarios

2009/08/16

Barcelona (Spain), Winnipeg (Canada), Las Vegas (USA), Moscow (Russia), Durban (South Africa), Vancouver (Canada) and Tokyo (Japan)… these were some of my Terrain view’s 3D scenarios published by Computamaps, a South African company I worked in not so long ago. By the way it was one of my best professional experiences ever… I enjoyed joining them a lot and It was very difficult leaving them (mainly because of Cynthia’s fruit salads;-)… Miss you guys a lot!!!

Hope you liked them.
Alberto
BA Geography
MSc GIS and Remote Sensing
GIS Technician
albertoconcejal -at -gmail.com

One more 3D building. Avenida de la Vega 28108. Restaurante Asiático SHENG. Madrid, Spain.

2009/08/15

I used to have lunch every thrusday there, at the ‘Restaurante Asiático SHENG’. I strongly recommend you ‘entremeses’ (In China you will find them as ‘dim-sum’) and Cantonese duck or Hong Kong duck (this was slightly spicy thou).  Very good food, very fast service and pretty cheap menu: 10,7 €… ideal for an IT worker!.

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These views were rendered using ‘V-RAY’ for Sketch-up.

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And now, Let’s go to Google Earth!

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(I have modified my kml using a extruded placemark we talked about a few posts ago).
Now Let’s have our business in 3D!!!!!!!!!!!!!!!.
Hope you like it.
Alberto
BA Geography
MSc GIS and Remote Sensing
GIS Technician
albertoconcejal -at -gmail.com

Definición de flujos de trabajo en 3D

2009/07/27

Protocolos de creación de escenarios en 3D, tratamiento de imágenes satélite, creación de modelos digitales de elevaciones -MDE- y del terreno -MDT- además de modelos en 3D. Google Sketchup, Google Earth, Global Mapper.

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Sketch-up google, edificios singulares. 3Ds, vrml, skp,…

2008/07/20

Presa de El Atazar, Madrid

Iglesia de Cadalso de los Vidrios

Torreon de Villarejo de Salvanés

Madrid 3d… Geovisualization live!

2008/07/16