I have a big trouble with a DTM. I have original DTM with SR WGS84/32633. Now I want merge at it a new DTM create from LiDAR data, but this (new DTM) have elevation that is 40/42 meters high that original DTM. I think that I must convert the elevation in correct geoid, but I don't know how do.

  • It sounds like your LiDAR is ellipsoidal heights. Consider contacting the agency that you procured the data from and ask for your height datum; LiDAR editing software should have a module for converting ELL to a nominated height datum. If this is not an option then you must procure the ellipsoidal to your height datum transformation but implementing that depends greatly on your available software. Or you can find a local company that captures LiDAR and request that they do it for you, for a small fee. Unless you're editing LAS files a lot it's very expensive to buy the required software. Commented Jun 26, 2017 at 5:37
  • Ok thank for answer. I used SAGA GIS to create DTM from Lidar. Now try to ask in SAGA GIS forum for help me.
    – Antonio79
    Commented Jun 26, 2017 at 9:25
  • What is your target SRID? Commented Jul 9, 2017 at 8:58

1 Answer 1


There is a utility that converts ellipsoidal height to geoidal height called GeoidEval which uses EGM2008/96/84. Online version is available and you can also download and use it on your pc. For more information, check out GeoidEval.


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