I am normalizing a large point cloud (>16 GB), for which I'm using a preprocessed DTM that I store as .tif. For smaller amounts of data, I would use an R script that lets me do this:
library(lidR) # load data las <- readLAS("pointcloud.las") dtm <- raster("dtm.tif") # normalize point cloud through subtraction nlas <- las - dtm
However these files are too big to process (I get
std::bad_alloc when running it in R). I wanted to use the LAStools Toolbox that is provided in ArcTools and I get stuck at the point where I define the groundpoints. I'd assume one would just specify the
dtm.tif here, however .tif apparently is no supported format, only .txt / .asc and other formats such as .shp, .las, ...
Converting my tif to .asc or .txt with ArcMap -> Conversion Tools will give me a dtm.txt / dtm.asc, but these cannot be read by the tool, as the 'dtm.asc' gives me:
ERROR: was not able to find header ERROR: cannot open lasreaderasc with file name 'dtm.asc' ERROR: could not open ground points file
And the 'dtm.txt' gives me:
ERROR: using zero ground points from 'dtm.txt'. try running with option '-all_ground_points'.
I have no experience with "raster files as asc/txt", yet was confident that this should work. Am I doing something wrong or overseeing something?
Is there a way to use .tif-files with the LAStools?
Or alternatively: Is there a better way to process these files (to normalize the point cloud)?