Hi everyone,
My name is Ramiro and I am master student at Freiburg University. I am
working on a master Thesis about forest stands and habitat mapping.
I have several asc files which I want to convert to spf format, for later
deriving elevation products and vegetation metrics. The files do not have
header and contain 7 columns: x, y, z, width, intensity, return number and
GPS time.
I would appreciate if someone could give any advise and how I
should proceed wiht it.
So far I tried as first step to convert them to las format (txt2las) and
from there to SPD.
My problem is that no number of return of a single pulse (n) is provided. I
want to add the information on n and I have been struggling for a while
already.
I worked the asc file with pandas to add n column, and tried to add n
values with pandas before converting to las format. I also tried to add
the values of n using laspy, creating a n array to replace num_returns. But
I did not succeed and I fail to understand how should I proceed. First
issue is that some pulses have more than 5 returns, even up to 9, which
lastools cannot digest apparently. The second is that even when
theoretically I calculate n right, I don't add the information properly to
the las file because the return number and the number of returns don't
match. For example, if I convert the las file to spd format I get such
warning error: SPD translate is ignoring Points because return
number is greater than number of Returns, or return number must be 1 and it
is not.
Would it be possible to skip the step of converting to las and convert the
files straight away from asc to SPD format?
If not, how do you think I should go about using lastools? Should I just do
not try to add the number of returns?
Sorry for sending such a long email and thanks in advance for your time.
Best regards,
Ramiro Silveyra
M. Sc. Forest Sciences
University of Freiburg
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