problems with negative intensity values

[Malcolm Williamson]

Hello,

I've got a some large exported .pts files from Leica Cyclone. In the first file I tried, the range of intensity is -2040 to -108. I ran txt2las64 with the arguments -parse xyziRGB -translate_then_scale_intensity 2048 16 . It complained at almost every line that the intensity value was out of range (I know, that's why I'm trying to translate it!), and then it populated the output with intensity values of mostly 0. I then tried it with the -translate_intensity 2048, with the same results. In the end, I used awk (well, mawk) to translate and scale the intensity values before converting them to LAS/LAZ. I thought that I had done this in the past directly with txt2las, but I may be mistaken. Thoughts?

Thanks,

    -Malcolm

Malcolm D. Williamson
Geospatial Applications and Education Manager
Center for Advanced Spatial Technologies
JBHT 304
1 University of Arkansas
Fayetteville AR 72701

[rapidlasso LAStools]

Hi Malcolm,

you did well to use awk to do this translation, because awk does not know about the LAS specification and do not care about. The specification allows just intensity values between 0 and 65535 (0xffff). We clamp the values during reading to a valid value, prior transform, and therefore can not handle negative values. We do not think this is an error, because the values are just invalid. Probably it would be possible to import them as extra byte, do the transformation on a signed integer base and put them afterwards to intensity.

Cheers,

Jochen @rapidlasso

[Malcolm Williamson]

Hi Jochen,

Thanks, I see your point. From my perspective, txt2las is an import tool, and the more flexibility it has, the more value it brings to its user (aka customer). On a positive note, thanks to Google Gemini, I now know much more about efficiently parsing large text documents in WSL!

Cheers,

-Malcolm
--------------------
Malcolm D. Williamson
Fayetteville, AR
479-790-2748  mal...@cast.uark.edu

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