As the title says, I am getting a NULL error in my code below.
# Read dtm for normalization
dtm <- raster("AlexSub2DTM.tif")
# Read trunks
trunks <- readOGR(dsn = "trunksfilterout2o.shp")
# read Large las as lasCatalog
las1<- readLAScatalog("Alex2swathclipped.las")
# Variables for processing
opt_output_files(las1) <- "./lasCat/laschunk_{ID}"
opt_chunk_size(las1) <- 495 # Processing chunks of 495 x 495
opt_chunk_buffer(las1) <- 15 # 15 ft buffer
opt_stop_early(las1) <- TRUE # or FALSE
opt_filter(las1) <- "-drop_z_below 15"
# Normalize
las1 <- normalize_height(las1, dtm,
na.rm = TRUE,
method = "bilinear",
overwrite = TRUE)
# CHM
opt_output_files(las1) <- "./lasCat/laschml_{ID}"
chml1 <- rasterize_canopy(las1, 0.25,
pitfree(c(0,2,5,10), c(0,1),
subcircle = 0.2),
overwrite = TRUE)
# Smoothing
ker = matrix(1,3,3)
chml1 = focal(chml1, w = ker, fun = median)
chml1 = focal(chml1, w = ker, fun = median)
# Save output
writeRaster(chml1, filename="As2_chml3_pf.tif", overwrite=TRUE)
# Tree Segmentation
algotr1 <- silva2016(chml1, trunks, exclusion = 0.5, ID = "treeID")
lastr1 <- segment_trees(las1, algotr1)
This is a small subset from a much larger project so scalability is non-negotiable and clipping is the smartest way for me to reduce total file size. My las is a non-rectangular ROI clip (pit-free and no voids/holes).
Would this cause the NULL error or should I look elsewhere?
(zip with all data is over 1Gb and won't upload)
lastr1 <- segment_trees(las1, algotr1) #> Processing [======>-----------------------------------------------------------] 8% (1/12) eta: 2m #> Error: NULL value passed as symbol address
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