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I'm currently doing a masters thesis on using drone photogrammetry to create a canopy height model of a grassland. This involves manually creating a DTM using an RTK GPS and using that data to normalise the DSM with lastools.

Unfortunately I'm getting stuck on converting my manually staked out points into a LAS file. I've tried both shp2las and txt2las with no luck. I'm very new to using lastools so I'm sure I'm doing something wrong.

My text file looks like this currently:

144.979281  -37.7011934     87.77934091
144.9792865 -37.70124286    87.15098529
144.979286  -37.70128589    86.92052778
144.9792809 -37.70132609    86.8250625

When I try to load this up into txt2las I get a "cannot parse" error.

Any ideas?

Vince
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Chris
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  • Attached is a link to the point shapefile

    https://www.dropbox.com/s/m7y6du5csy2143v/Bababi%20DTM-Shapefile.zip?dl=0

     – Chris Nov 07 '21 at 10:42
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    Welcome to GIS SE. As a new user, please take the [Tour]. "No luck" isn't a very descriptive breakdown of what you tried. We use a Focused question/Best answer model, so pick one of the two ways (probably txt2las since that's the format you show) and provide the exact command usage and exact output. – Vince Nov 07 '21 at 12:07
  • Can you elaborate on "...normalise the DSM..."? And why do you want to turn these few points into a LAS file? – Pointdump Nov 07 '21 at 14:32
  • Okay so here's the context, I'm attempting to follow this article:

    https://rapidlasso.com/2017/06/13/integrating-external-ground-points-in-forests-to-improve-dtm-from-dense-matching-photogrammetry/#comments

    I need to height normalize my DSM so that I can generate a canopy height model. There is too much vegetation to automatically extract a DTM, hence why I have to manually create one using an RTK GPS.

    The good news is that I managed to get txt2las to parse my file and generate a point cloud.

    Unfortunately now, I'm stuck on the next step, densifying the dtm using the las2dem tool.

     – Chris Nov 08 '21 at 03:01
  • When I enter the newly generated laz file and attempt to densify, my resulting output is a laz file with no points! Could it be because I'm missing projection information? Attached is a screenshot of the GUI and the txt2las file I'm currently working with

    https://www.dropbox.com/s/c0l0wnj9cyd6np3/Screenshot%20%2816%29.png?dl=0

    https://www.dropbox.com/s/8l9twmavx4o82zp/attempt4.laz?dl=0

     – Chris Nov 08 '21 at 03:07

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