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Posts Tagged ‘MDE’

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/)

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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

WMS in Google Earth.

2009/08/04

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…

WMS

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 LAND COVER

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.

LEYENDA_CORINE

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

chiclana01

This is once we get connected via WMS to the place where you can get those maps (http://www.idee.es/wms/IGN-Corine/IGN-Corine?). 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.

 chiclana02

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

chiclana03

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)…

chiclana04

More geographic post to come very soon!!!

Alberto

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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