I did a drone flight over a forest plantation and got the DSM and DTM. Later, I was interested in calculating the height of the trees within a plot. For this, I did a subtraction between the DSM and DTM. However, when verifying the height of the trees in the CHM, these are not correct, because they vary with respect to what was reported in the field. ¿Does anyone know why this could be happening and how it can be solved?

  • 2
    The two measurements will never be exactly the same. How far out are they? Is one systematically bigger or smaller than the other everywhere? Did you simply subtract DSM from DTM or is there a more complex canopy height model involved? What software produced your DSM and DTM from the data? – Spacedman May 25 at 14:36
  • In the CHM the average height is 5-6 meters. While the one reported in the field (real) is 9-10 meters. I only subtract DSM from DTM. And finally, I obtained the DSM and DTM from the software WebODM. – Javier Hernández May 25 at 14:43
  • 1
    Exactly which processing steps did you perform? Have you looked at the pointcloud and made sure your max height is actually the tree top and not lower in the canopy – BERA May 25 at 15:01
  • I obtained the DSM and DTM from the WebODM software and then in QGIS, I subtract DSM from DTM. Finally, also in QGIS. I made a circular buffer of 1.3 meters at the center point of each tree and obtained the maximum altitude with the tool "Zonal statistics". – Javier Hernández May 25 at 16:31
  • 1
    Welcome to GIS SE. As a new user, please take the Tour to better understand how our Focused question/Best answer model operates. Please Edit the Question in response to requests for clarification. It's unfair to those who would help to need to review comments for critical information. – Vince May 26 at 18:23

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.