Hello!
I am working with LIDAR data of an Italian Region for my PhD and I am facing a lot of problem with them.
My objective is to obtain a DEM and a DSM
from this data. I am using lastools on ArcMap 10.3.
First, I tried to understand my data. I have more than one strip for the same area, in the same date, with different number of cloud point. Looking to the classification I discovered that there are 4 classes determined based on the pulse return.
Thus, the first return is set, as unclassified (which lead to more than a half of the cloudpoints unclassified), the second return is classified as ground, the 3th return as low vegetation and the 4th as medium vegetation. The data do not have a last return.
Looking to the classification it is incorrect. It is easily detect from a quick overview of the area but also when I tried to obtain a DEM using these classification. This is the process I followed to built a DEM (lasground - lasheight - las2dem) but also using (las to multipoint - point to raster) the result was the same as shown in the screenshot nr. 1. I am missing a lot of points and also I have a lot of noisy points classify as ground.
Thus. I am trying to reclassify the data but, it looks impossible.
Here the steps that I followed:
Then I tried to classify by selection in ARCMAP 10.3 and change codes but they didn’t. Moreover when I used las2las(filter) to drop the classification, it didn't. I am afraid that something is wrong with this data but I don't know what it is.
This is how my original LIDAR data looks in 3D view and if I try to make a Profile view from my las dataset in ArcMap I will obtain a vertical line. As shown in the screenshot nr2. (from ArcMap) and screenshot nr.3 (LIDAR360 software) they are strange although they have a z value that has also negative values (-200). Now I suppose the z value is not sort correctly but I am not sure about this.
Can anyone help me to solve these problem?
Thanks!
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