Error reading data with spectral reflectance attributes

[seanreilly66]

Hi everyone,

I've run into a hurdle with which I would really appreciate some help.

I have a collection of las files generated from structure from motion which have additional spectral attributes recorded as decimal reflectance values, rather than 8 bit integers. These loaded fine in the old version of lidR but we have been unable to open them since the major updates a bit ago. As luck would have it, most colors had been added as full names (e.g., red instead of R) so lidR does not flag them as a default attribute. However, our near infrared data is stored as nir. Consequently, we get the following error when attempting to load a file:

Attribute 'nir' renamed 'NIR' to match with default attribute names.
Error: Invalid data: NIR is not an integer

Is there a way around this within readLAS? Alternatively, is there a way to modify the attribute name (e.g., change it to nir_reflectance) so lidR will not flag it?

Thank you greatly for any help.

Sean

[Jean-Romain]

These loaded fine in the old version of lidR but we have been unable to open them since the major updates a bit ago

Please report an issue with a minimal reproducible example. Is is related to r-lidar/rlas#59 ?

Alternatively, is there a way to modify the attribute name (e.g., change it to nir_reflectance) so lidR will not flag it?

Sure, use names()

library(lidR)
LASfile <- system.file("extdata", "Megaplot.laz", package="lidR")
las = readLAS(LASfile)
n = names(las@data)
n[4] = "time"
names(las@data) = n
names(las)

You can tweak everything manually to reach your goal but I need a reproducible example to help

[seanreilly66]

Thanks for the help. Here's a simple reprex of the problem.

library(lidR)

las <- LAS(data = data.frame(
  X = runif(100, 1, 10),
  Y = runif(100, 1, 10),
  Z = runif(100, 1, 10)
))

las <- LAS(df)

nir = runif(100)

las <- add_lasattribute(las, x = nir, name = 'nir', desc = 'nir')

writeLAS(las, 'temp/nir_error.las')

readLAS('temp/nir_error.las')

I hope this helps. Since the file fails during loading, unfortunately names() will not work. Is there any way to update the attribute names via the header without loading the entire file?

[Jean-Romain]

Ok I see. Please report it as a bug.

[seanreilly66]

Issue created here #659

Thanks for all that you do. The package is incredible.