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Archive for March, 2015

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

dtm-validation-02

This is the path we have to draw in Google Earth

dtm-validation-03

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

dtm-validation-01

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

dtm-validation-04

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.

dtm-validation-05

dtm-validation-06

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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