Vertical Datum Transformation

[Natalie Vogel]

Hi all - I was curious what people use to transform your vertical datum in lastools? Some people have mentioned a las2las and lasheight. I'm curious if anyone uses lasvdatum? If so, what transformation parameters do you use? I'm trying to transform my VD to NAVD88. I already have my geoid set to 2012b and my horizontal datum is transformed. 

Any advice is appreciated. Thanks!

-Natalie

[Nelson Mattie]

Hello, 

In LAStools, the lasvdatum tool is specifically designed for transforming LiDAR data from ellipsoidal to orthometric elevations, using a grid format typically provided by national surveys. This tool addresses the vertical differences between a geoidal model and an elliptical model of the Earth. By default, the conversion is from ellipsoidal elevations to geoidal (or orthometric) elevations​​.

For your specific requirement of transforming the vertical datum to NAVD88, you can use lasvdatum with the appropriate geoid grid. If you already have your geoid set to 2012b, you would use a command something like this:

lasvdatum -i in.laz -epsg xxxxx -vgrid g2012bu0.gtx -o out.laz

Get the -epsg code from here https://epsg.io/ normally in UTM (for example: UTM 12N + WGS 84 ellipsoidal)

This command will take your input file (in.laz), apply the transformation using the g2012bu0.gtx geoid grid (which corresponds to the geoid model you mentioned), and output the transformed file (out.laz)​​.

While las2las and lasheight are also commonly used for various transformations and adjustments in LAStools, lasvdatum is more specialized for vertical datum transformations, especially when dealing with geoid models and converting between ellipsoidal and orthometric elevations.

Finally, I've developed a GPT available at  https://chat.openai.com/g/g-77IlZRj3A-lidar-ai-lastools-helper designed to generate LAStools code for creating batch scripts to process LiDAR data. Additionally, it offers assistance with inquiries about the software, tools, arguments, and general LiDAR-related topics. If you possess an OpenAI GPT Plus subscription, you are welcome to give it a try..

Nelson Mattie, PhD© Remote Sensing

UNIVERSITY OF ALBERTA
Centre for Earth Observation Sciences
Department of Earth & Atmospheric Sciences
2-038 Centennial Centre for Interdisciplinary Science (CCIS)
Edmonton, AB. T6G 2E3. Canada.
Phone: +1 587.936.1278 | Email: matt...@ualberta.ca

[Sasa Lazic]

Hello Mr. Nelson, can you tell me where the lasvdatum application can be downloaded? I'm unable to access the provided link.

Thank you for your response.

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[Jochen Rapidlasso]

Hi Sasa,
you can download LAStools at
    https://rapidlasso.de
the direct link is
    https://downloads.rapidlasso.de/LAStools.zip

You will find a 32bit and a 64bit version (lasvdatum64).

We recommend to use the 64bit version.

Please see

    https://rapidlasso.de/customer-support/

for support and licensing informations.

Best regards,

Jochen @rapidlasso