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I have VHR imagery, 5 cm pixel, and I want to create a DEM but this image has high trees and when I take my model I cant take a real elevation because DEM is not the height of the terrain.

Could I eliminate this effect?

  • If your images are captured from a drone and meet some requirements (e.g., overlap between one shot and the adjacents), you can build a 3D model and a DEM. Algorithms exist to classify the point cloud from which the 3D model and the DEM are based, in order discriminate between ground and off ground points. The latter can be removed and the elevation of the resulting ‘holes’ can be interpolated; but the results would not be that precise however. – NewAtGis Jan 15 '18 at 23:21
  • If you can convert/export your elevations as LAS I would suggest LASTools LASGround rapidlasso.com/lastools/lasground to classify ground/nonground then LAS2LAS rapidlasso.com/lastools/las2dem with -keep_class 2 switch to generate a ground level DEM if at all possible among your trees... if the drone can't see the ground it can't map the ground! – Michael Stimson Jan 15 '18 at 23:33
  • Similar that Agisoft interpolation. Can you said me, one example the algorithm exist for classification. Thanks – Dinosca Jan 15 '18 at 23:35
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There's not really enough information in your question.

If you have many overlapping images you can use something like Pix4D to generate a 3D model of some form and an orthoimage using structure from motion algorithms. But, unlike LiDAR, this will not be classified.

As far as I know, you can't automatically remove trees and buildings from a 3D model generated from this kind of algorithm. Plus, imagery does not see through trees as LiDAR can (to some extent). So, you'll probably end up with a model that has lots of canopy and very little ground, depending on what the tree cover is like.

Your question does suggest you already have a DEM, and so perhaps you could try classifying the dataset to identify areas that are ground, and then exclude other areas and interpolate a new model based on that, but it's not something that is standard.

  • Thanks for you answers, i want classified my LAS point, and I was created a DEM, and I was overlapping my las date. – Dinosca Feb 8 '18 at 23:59

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