Hi Dan,
thanks for the answer.
I wrote my schema based on the examples,
adding fields and the correct data type.
I still have a problem, though.
Each row in the asc file represents a point, namely return.
The returns are sorted, so that
returns from same pulse are consecutive.
I would like that once converted to spd the data would be organized in
pulses
and within each pulse have the returns.
I don't know I could organize the data and parse to spd
to obtain a spd file with the returns grouped in pulses.
In the asc file, I can attribute them to a pulse using a loop by looking at
their return number
and/or gps time (it is same time for returns of one pulse).
Could you gave me any hint?
What information should I add to the asc file so spd translate can read the
schema and
organize pulses? Would I need to add pulse ID and number of returns?
Or I have to reorganize the asc file?
Thanks again for your attention.
Best Regards,
Ramiro
2014-12-02 20:16 GMT+01:00 Daniel Clewley <[email protected]>:
> Hi Ramiro,
>
> Yes, you can import ASCII files directly into SPDLib. You just need to
> define an XML schema telling spdtranslate which data is in which column.
> There are some examples here:
>
>
> https://bitbucket.org/petebunting/spdlib/src/a341032e01e0/schemas/?at=default
>
> Thanks,
>
> Dan
>
> On 2 Dec 2014, at 19:01, Ramiro Silveyra González <[email protected]>
> wrote:
>
> 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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