Hello Jean-Romain,
Thank you for the very useful and powerful package lidR. I have been using it for some months now and I am trying to compute standard metrics using the grid_metrics() function, with .stdmetrics as the func argument.
I am having an issue regarding the computation of the total intensity (itot, which is part of stdmetrics_i). The error message is about a column being of type double instead of integer. I copy the error message here for information :
"Error in `[.data.table`(las@data, , if (!anyNA(.BY)) c(eval(call)), by = cells) :
Column 1 of result for group 59 is type 'double' but expecting type 'integer'. Column types must be consistent for each group."
I have investigated the issue and it seems that the total intensity, which is defined as the sum of all the returns' intensities, reaches a too big value to be kept as an integer and is seen as a double by R. I tried to "manually" compute the sum of intensities using a custom function rather than .stdmetrics_i in grid_metrics(), and I got the same error. Then I added a conversion of the result as an integer using the as.integer64() function from the bit64 package (which allows conversion of "big" integers), and the issue was solved.
Is there a way to "force" stdmetrics_i to keep the itot result as an integer ? Since I'm computing grid_metrics() over a whole LAScatalog there are only a few chunks where itot is too big, but it ruins the whole computation. Thank you very much for your feedback !
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