Global Mapper v25.0

UAV Photogrammetry vegetation removal

imagecatcher
imagecatcher Global Mapper User
edited June 2014 in Elevation Data
Hello GM users,
Firstly, I'm a novice. I am beginning aerial mapping using the Sensefly eBee UAV. I need to 'clean' up the terrain and basically get 'down to earth'. I have read a few threads that 'beat around the bush' but they are either above my level of understanding or aim to get a different result. Im sure you guys know my problem: I import my LAS data, create an elevation grid, then generate contours and bang all the trees are contoured.

Secondly, In wooded areas I can see the ground in places and I am sure this terrain is higher than other contoured terrain yet no contours are drawn (say under the trees). Can I use the digitiser or something and identify some ground?

Third, why are some parts of the forest flattened in photogrametry/point cloud while other trees are extruded?

Thanks in advance
Troy
NB: my 'generated contours' layer has 828558 features covering an area of 250x250m, and takes 1.5hrs to generate!

Comments

  • Jasmine_BMG
    Jasmine_BMG BMG Staff
    edited June 2014
    Hello Troy,

    What version of Global Mapper are you using? You will want to isolate the Lidar points being used to those classified as 'ground'. If you have Global Mapper v15, can elect to only import the ground Lidar points by unselecting all others under the 'Select Lidar Point Classifications to Input' on the right, and then create your contours from the imported ground points (this should be faster, as well). You can also go to Tools > Configuration and then the Lidar tab where you can elect to show only the ground points as well.

    I deactivated my Lidar module and still have these options mentioned above, but let me know if you do not see them. If you would like to try the Lidar Module out for reclassifying points please send me an email at geohelp@bluemarblegeo.com. It makes some tasks much simpler when it comes to working with Lidar data - though is by no means necessary for working with Lidar data in Global Mapper.

    Regards,

    Jasmine