Calculation of LiDAR metrics

[Rodrigo Saavedra]

Dear,

I am working on the processing of LiDAR data applied to forest inventories, for this I need to generate some metrics with LasTools from which I have been able to generate those that correspond to percentiles, density and cov. However there are some that I lack and are those of the following table.

Can you tell me how I can generate these metrics and what code should I add to LASTools?

METRICAS

Total return count above 5.00

Percentage first returns above 5.00

Percentage all returns above 5.00

(All returns above 5.00) / (Total first returns) * 100

First returns above 5.00

All returns above 5.00

Percentage first returns above mean

Percentage first returns above mode

Percentage all returns above mean

Percentage all returns above mode

(All returns above mean) / (Total first returns) * 100

(All returns above mode) / (Total first returns) * 100

First returns above mean

First returns above mode

All returns above mean

All returns above mode

Total first returns

Total all returns

[Mauro Assis]

Rodrigo,

You must use lascanopy, http://www.cs.unc.edu/~isenburg/lastools/download/lascanopy_README.txt.

Cheers,

Mauro Assis

INPE
Brasil

[Rodrigo Saavedra]

Dear Mauro,

Thanks for your help, as well you indicate if I am using lascanopy, where in the line of code to obtain the metrics of prcentiles, dns and cover I add the following:

-p 20 90 95

-dns: (# of first returns> cutoff) / (total # of first returns in the pixel) * 100

-cov: (# of all returns> cutoff) / (total # of all returns in the pixel) * 100

What I describe above is what I understand that is not calculated ?. Of being as you can see are not the same metrics that I would like to get, my question is: What parameters can I add to my command line to get each of the ones I describe below ?:

METRICAS

Total return count above 5.00

Percentage first returns above 5.00

Percentage all returns above 5.00

(All returns above 5.00) / (Total first returns) * 100

First returns above 5.00

All returns above 5.00

Percentage first returns above mean

Percentage first returns above mode

Percentage all returns above mean

Percentage all returns above mode

(All returns above mean) / (Total first returns) * 100

(All returns above mode) / (Total first returns) * 100

First returns above mean

First returns above mode

All returns above mean

All returns above mode

Total first returns

Total all returns

Greetings and thanks

[Martin Isenburg]

Hello,

 What parameters can I add to my command line to get each of the ones I describe below ?:

METRICAS

Total return count above 5.00

lascanopy -i normalized.laz -c 5.0 1000.0

 

Percentage first returns above 5.00

lascanopy -i normalized.laz -cover_cutoff 5.0 -cov

 

Percentage all returns above 5.00

lascanopy -i normalized.laz -cover_cutoff 5.0 -dns

 

(All returns above 5.00) / (Total first returns) * 100

n/a ... use two runs plus raster calculator

 

First returns above 5.00

lasgrid -i  normalized.laz -keep_first -keep_z_above 5.0 -counter_16bit

 

All returns above 5.00

lasgrid -i  normalized.laz -keep_z_above 5.0 -counter_16bit

 

Percentage first returns above mean

n/a

 

Percentage first returns above mode

n/a ... who uses the mode for LiDAR?

 

Percentage all returns above mean

n/a but compare to lascanopy -i normalized.laz -b 50

 

Percentage all returns above mode

n/a but compare to lascanopy -i normalized.laz -b 50

 

(All returns above mean) / (Total first returns) * 100

n/a

 

(All returns above mode) / (Total first returns) * 100

n/a ... who uses the mode for LiDAR?

 

First returns above mean

n/a ... but maybe construct a mean surface with lasgrid and classify points below it with lasheight and then use lasgrid to count

 

First returns above mode

n/a ... who uses the mode for LiDAR?

 

All returns above mean

n/a ... but maybe construct a mean surface with lasgrid and classify points below it with lasheight and then use lasgrid to count

 

All returns above mode

n/a ... who uses the mode for LiDAR?

 

Total first returns

lasgrid -i  normalized.laz -keep_first -counter_16bit

 

Total all returns

lasgrid -i  normalized.laz -counter_16bit

Greetings and thanks

[Rodrigo Saavedra]

Dear Martin,

As you say there are some metrics that are used very little or who uses them ?, so this is just what I was looking for. Thank you very much for the help.

Regards,