Accessing GEDI full waveform LiDAR via PulseWaves API

[Martin Isenburg]

Hello,

if all goes well the GEDI instrument of NASA that was launched this week should be producing LiDAR waveforms soon. Oh yes, congrats once more to the GEDI mice ... aehh ... knights:

http://www.facebook.com/LAStools/photos/a.183097501752702/2080258518703248

The GEDI system will only be able to produce 15 billion shots so each one should be made worthwhile and storing the geolocated full waveforms in PulseWaves format might be one way of going about this ... (-:

The GEDI LiDAR systems contains three lasers with a wavelength of 1064 nanometers that shoot pulses of 11 - 15 nanoseconds in duration about 242 times per second with a power of 10 millijoules each down towards the Earth’s surface. The beam divergence of 56 milliradians results in photon-illuminated footprints that are averaging 22 meters in diameter that are separated by 60 m along-track and by 600 m across track. Each GEDI laser shot will result in a waveform that contains information about the vegetation canopy and the topography underneath. For a lot of additional details see this page:

https://directory.eoportal.org/web/eoportal/satellite-missions/content/-/article/iss-gedi

What makes this really interesting to me personally is the potential for storing the georeferenced full waveform data (see attached image) to the PulseWaves format. In the design of the format we included a special "offset" value that was designed to be added to the time-of-flight duration to account for space-based LiDAR systems such as the GEDI.

The Level-1 product is supposed to be that "geolocated waveforms". Rather than converting the data to PulseWaves we could also expose the data via a new reader that reads the native GEDI format and presents it as PulseWaves data, just like it was done for LVIS data.

Is there a full waveform format description for GEDI's  Level-1 products available?  

Regards.

Martin @rapidlasso

[Ho Tong Minh Dinh]

Dear Martin Isenburg,

For the question : 'Is there a full waveform format description for GEDI's  Level-1 products available? '

It is still not available. But it will strongly use the format HDF developed in LVIS data recently.

You can check it here :

https://lvis.gsfc.nasa.gov/Home/GabonWorkshop.html

Format description: https://lvis.gsfc.nasa.gov/data_sets/2016_gabon/LVIS_GabonAfriSAR_data_release.pdf

L1: https://lvis.gsfc.nasa.gov/workshop/LVIS_Mondah_level1b.h5

L2: https://lvis.gsfc.nasa.gov/workshop/LVIS_Mondah_level2.TXT

It is interesting to support such format to work on PulseWaves.

Thank you in advance.

Best regards,

Dinh

[Adrian Dwiputra]

Hi Martin,

I have just learned that after a long wait, we are able to download the GEDI data (level 1B, 2A, and 2B) at a specific area of interest using the so-called "GEDI Finder" service url. In its current format, is it possible to process level 1B GEDI data in the PulseWaves API?

Apologies if it's already implied somewhere earlier because I wasn't super clear to me.

Cheers,

Adrian

[Martin Isenburg]

Hello,

one of the first things I had done when GEDI announced it was releasing data soon (like a year ago (-;) was to contact those I knew working on the project and asking them for a detailed format description to see whether it could be fully mapped to PulseWaves as the format was originally designed to accommodate satellite based LiDAR. Do you have a concise problem statement of what parts of the GEDI data you want to access through the PulseWaves API and for what purpose? Having an exact use case at hand may make this process more tangible to get started.

Regards from Indonesia,

Martin

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[Adrian Dwiputra]

Hi Martin,

 

What a nice surprise to know that you are in Indonesia! It makes me miss home more. I hope you are having a good time.

 

I am still at the beginning of the learning curve but I am exploring its potential to be used in identifying specific vegetation types in the sub-humid tropics. So, I think about having some vegetation structural metrics out of the GEDI’s full waveform data. Please let me know if this makes any sense at all.

 

Cheers,

Adrian

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